| /* |
| * kernel/workqueue.c - generic async execution with shared worker pool |
| * |
| * Copyright (C) 2002 Ingo Molnar |
| * |
| * Derived from the taskqueue/keventd code by: |
| * David Woodhouse <dwmw2@infradead.org> |
| * Andrew Morton |
| * Kai Petzke <wpp@marie.physik.tu-berlin.de> |
| * Theodore Ts'o <tytso@mit.edu> |
| * |
| * Made to use alloc_percpu by Christoph Lameter. |
| * |
| * Copyright (C) 2010 SUSE Linux Products GmbH |
| * Copyright (C) 2010 Tejun Heo <tj@kernel.org> |
| * |
| * This is the generic async execution mechanism. Work items as are |
| * executed in process context. The worker pool is shared and |
| * automatically managed. There is one worker pool for each CPU and |
| * one extra for works which are better served by workers which are |
| * not bound to any specific CPU. |
| * |
| * Please read Documentation/workqueue.txt for details. |
| */ |
| |
| #include <linux/module.h> |
| #include <linux/kernel.h> |
| #include <linux/sched.h> |
| #include <linux/init.h> |
| #include <linux/signal.h> |
| #include <linux/completion.h> |
| #include <linux/workqueue.h> |
| #include <linux/slab.h> |
| #include <linux/cpu.h> |
| #include <linux/notifier.h> |
| #include <linux/kthread.h> |
| #include <linux/hardirq.h> |
| #include <linux/mempolicy.h> |
| #include <linux/freezer.h> |
| #include <linux/kallsyms.h> |
| #include <linux/debug_locks.h> |
| #include <linux/lockdep.h> |
| #include <linux/idr.h> |
| |
| #include "workqueue_sched.h" |
| |
| enum { |
| /* global_cwq flags */ |
| GCWQ_MANAGE_WORKERS = 1 << 0, /* need to manage workers */ |
| GCWQ_MANAGING_WORKERS = 1 << 1, /* managing workers */ |
| GCWQ_DISASSOCIATED = 1 << 2, /* cpu can't serve workers */ |
| GCWQ_FREEZING = 1 << 3, /* freeze in progress */ |
| GCWQ_HIGHPRI_PENDING = 1 << 4, /* highpri works on queue */ |
| |
| /* worker flags */ |
| WORKER_STARTED = 1 << 0, /* started */ |
| WORKER_DIE = 1 << 1, /* die die die */ |
| WORKER_IDLE = 1 << 2, /* is idle */ |
| WORKER_PREP = 1 << 3, /* preparing to run works */ |
| WORKER_ROGUE = 1 << 4, /* not bound to any cpu */ |
| WORKER_REBIND = 1 << 5, /* mom is home, come back */ |
| WORKER_CPU_INTENSIVE = 1 << 6, /* cpu intensive */ |
| WORKER_UNBOUND = 1 << 7, /* worker is unbound */ |
| |
| WORKER_NOT_RUNNING = WORKER_PREP | WORKER_ROGUE | WORKER_REBIND | |
| WORKER_CPU_INTENSIVE | WORKER_UNBOUND, |
| |
| /* gcwq->trustee_state */ |
| TRUSTEE_START = 0, /* start */ |
| TRUSTEE_IN_CHARGE = 1, /* trustee in charge of gcwq */ |
| TRUSTEE_BUTCHER = 2, /* butcher workers */ |
| TRUSTEE_RELEASE = 3, /* release workers */ |
| TRUSTEE_DONE = 4, /* trustee is done */ |
| |
| BUSY_WORKER_HASH_ORDER = 6, /* 64 pointers */ |
| BUSY_WORKER_HASH_SIZE = 1 << BUSY_WORKER_HASH_ORDER, |
| BUSY_WORKER_HASH_MASK = BUSY_WORKER_HASH_SIZE - 1, |
| |
| MAX_IDLE_WORKERS_RATIO = 4, /* 1/4 of busy can be idle */ |
| IDLE_WORKER_TIMEOUT = 300 * HZ, /* keep idle ones for 5 mins */ |
| |
| MAYDAY_INITIAL_TIMEOUT = HZ / 100, /* call for help after 10ms */ |
| MAYDAY_INTERVAL = HZ / 10, /* and then every 100ms */ |
| CREATE_COOLDOWN = HZ, /* time to breath after fail */ |
| TRUSTEE_COOLDOWN = HZ / 10, /* for trustee draining */ |
| |
| /* |
| * Rescue workers are used only on emergencies and shared by |
| * all cpus. Give -20. |
| */ |
| RESCUER_NICE_LEVEL = -20, |
| }; |
| |
| /* |
| * Structure fields follow one of the following exclusion rules. |
| * |
| * I: Modifiable by initialization/destruction paths and read-only for |
| * everyone else. |
| * |
| * P: Preemption protected. Disabling preemption is enough and should |
| * only be modified and accessed from the local cpu. |
| * |
| * L: gcwq->lock protected. Access with gcwq->lock held. |
| * |
| * X: During normal operation, modification requires gcwq->lock and |
| * should be done only from local cpu. Either disabling preemption |
| * on local cpu or grabbing gcwq->lock is enough for read access. |
| * If GCWQ_DISASSOCIATED is set, it's identical to L. |
| * |
| * F: wq->flush_mutex protected. |
| * |
| * W: workqueue_lock protected. |
| */ |
| |
| struct global_cwq; |
| |
| /* |
| * The poor guys doing the actual heavy lifting. All on-duty workers |
| * are either serving the manager role, on idle list or on busy hash. |
| */ |
| struct worker { |
| /* on idle list while idle, on busy hash table while busy */ |
| union { |
| struct list_head entry; /* L: while idle */ |
| struct hlist_node hentry; /* L: while busy */ |
| }; |
| |
| struct work_struct *current_work; /* L: work being processed */ |
| struct cpu_workqueue_struct *current_cwq; /* L: current_work's cwq */ |
| struct list_head scheduled; /* L: scheduled works */ |
| struct task_struct *task; /* I: worker task */ |
| struct global_cwq *gcwq; /* I: the associated gcwq */ |
| /* 64 bytes boundary on 64bit, 32 on 32bit */ |
| unsigned long last_active; /* L: last active timestamp */ |
| unsigned int flags; /* X: flags */ |
| int id; /* I: worker id */ |
| struct work_struct rebind_work; /* L: rebind worker to cpu */ |
| }; |
| |
| /* |
| * Global per-cpu workqueue. There's one and only one for each cpu |
| * and all works are queued and processed here regardless of their |
| * target workqueues. |
| */ |
| struct global_cwq { |
| spinlock_t lock; /* the gcwq lock */ |
| struct list_head worklist; /* L: list of pending works */ |
| unsigned int cpu; /* I: the associated cpu */ |
| unsigned int flags; /* L: GCWQ_* flags */ |
| |
| int nr_workers; /* L: total number of workers */ |
| int nr_idle; /* L: currently idle ones */ |
| |
| /* workers are chained either in the idle_list or busy_hash */ |
| struct list_head idle_list; /* X: list of idle workers */ |
| struct hlist_head busy_hash[BUSY_WORKER_HASH_SIZE]; |
| /* L: hash of busy workers */ |
| |
| struct timer_list idle_timer; /* L: worker idle timeout */ |
| struct timer_list mayday_timer; /* L: SOS timer for dworkers */ |
| |
| struct ida worker_ida; /* L: for worker IDs */ |
| |
| struct task_struct *trustee; /* L: for gcwq shutdown */ |
| unsigned int trustee_state; /* L: trustee state */ |
| wait_queue_head_t trustee_wait; /* trustee wait */ |
| struct worker *first_idle; /* L: first idle worker */ |
| } ____cacheline_aligned_in_smp; |
| |
| /* |
| * The per-CPU workqueue. The lower WORK_STRUCT_FLAG_BITS of |
| * work_struct->data are used for flags and thus cwqs need to be |
| * aligned at two's power of the number of flag bits. |
| */ |
| struct cpu_workqueue_struct { |
| struct global_cwq *gcwq; /* I: the associated gcwq */ |
| struct workqueue_struct *wq; /* I: the owning workqueue */ |
| int work_color; /* L: current color */ |
| int flush_color; /* L: flushing color */ |
| int nr_in_flight[WORK_NR_COLORS]; |
| /* L: nr of in_flight works */ |
| int nr_active; /* L: nr of active works */ |
| int max_active; /* L: max active works */ |
| struct list_head delayed_works; /* L: delayed works */ |
| }; |
| |
| /* |
| * Structure used to wait for workqueue flush. |
| */ |
| struct wq_flusher { |
| struct list_head list; /* F: list of flushers */ |
| int flush_color; /* F: flush color waiting for */ |
| struct completion done; /* flush completion */ |
| }; |
| |
| /* |
| * All cpumasks are assumed to be always set on UP and thus can't be |
| * used to determine whether there's something to be done. |
| */ |
| #ifdef CONFIG_SMP |
| typedef cpumask_var_t mayday_mask_t; |
| #define mayday_test_and_set_cpu(cpu, mask) \ |
| cpumask_test_and_set_cpu((cpu), (mask)) |
| #define mayday_clear_cpu(cpu, mask) cpumask_clear_cpu((cpu), (mask)) |
| #define for_each_mayday_cpu(cpu, mask) for_each_cpu((cpu), (mask)) |
| #define alloc_mayday_mask(maskp, gfp) zalloc_cpumask_var((maskp), (gfp)) |
| #define free_mayday_mask(mask) free_cpumask_var((mask)) |
| #else |
| typedef unsigned long mayday_mask_t; |
| #define mayday_test_and_set_cpu(cpu, mask) test_and_set_bit(0, &(mask)) |
| #define mayday_clear_cpu(cpu, mask) clear_bit(0, &(mask)) |
| #define for_each_mayday_cpu(cpu, mask) if ((cpu) = 0, (mask)) |
| #define alloc_mayday_mask(maskp, gfp) true |
| #define free_mayday_mask(mask) do { } while (0) |
| #endif |
| |
| /* |
| * The externally visible workqueue abstraction is an array of |
| * per-CPU workqueues: |
| */ |
| struct workqueue_struct { |
| unsigned int flags; /* I: WQ_* flags */ |
| union { |
| struct cpu_workqueue_struct __percpu *pcpu; |
| struct cpu_workqueue_struct *single; |
| unsigned long v; |
| } cpu_wq; /* I: cwq's */ |
| struct list_head list; /* W: list of all workqueues */ |
| |
| struct mutex flush_mutex; /* protects wq flushing */ |
| int work_color; /* F: current work color */ |
| int flush_color; /* F: current flush color */ |
| atomic_t nr_cwqs_to_flush; /* flush in progress */ |
| struct wq_flusher *first_flusher; /* F: first flusher */ |
| struct list_head flusher_queue; /* F: flush waiters */ |
| struct list_head flusher_overflow; /* F: flush overflow list */ |
| |
| mayday_mask_t mayday_mask; /* cpus requesting rescue */ |
| struct worker *rescuer; /* I: rescue worker */ |
| |
| int saved_max_active; /* W: saved cwq max_active */ |
| const char *name; /* I: workqueue name */ |
| #ifdef CONFIG_LOCKDEP |
| struct lockdep_map lockdep_map; |
| #endif |
| }; |
| |
| struct workqueue_struct *system_wq __read_mostly; |
| struct workqueue_struct *system_long_wq __read_mostly; |
| struct workqueue_struct *system_nrt_wq __read_mostly; |
| struct workqueue_struct *system_unbound_wq __read_mostly; |
| EXPORT_SYMBOL_GPL(system_wq); |
| EXPORT_SYMBOL_GPL(system_long_wq); |
| EXPORT_SYMBOL_GPL(system_nrt_wq); |
| EXPORT_SYMBOL_GPL(system_unbound_wq); |
| |
| #define CREATE_TRACE_POINTS |
| #include <trace/events/workqueue.h> |
| |
| #define for_each_busy_worker(worker, i, pos, gcwq) \ |
| for (i = 0; i < BUSY_WORKER_HASH_SIZE; i++) \ |
| hlist_for_each_entry(worker, pos, &gcwq->busy_hash[i], hentry) |
| |
| static inline int __next_gcwq_cpu(int cpu, const struct cpumask *mask, |
| unsigned int sw) |
| { |
| if (cpu < nr_cpu_ids) { |
| if (sw & 1) { |
| cpu = cpumask_next(cpu, mask); |
| if (cpu < nr_cpu_ids) |
| return cpu; |
| } |
| if (sw & 2) |
| return WORK_CPU_UNBOUND; |
| } |
| return WORK_CPU_NONE; |
| } |
| |
| static inline int __next_wq_cpu(int cpu, const struct cpumask *mask, |
| struct workqueue_struct *wq) |
| { |
| return __next_gcwq_cpu(cpu, mask, !(wq->flags & WQ_UNBOUND) ? 1 : 2); |
| } |
| |
| /* |
| * CPU iterators |
| * |
| * An extra gcwq is defined for an invalid cpu number |
| * (WORK_CPU_UNBOUND) to host workqueues which are not bound to any |
| * specific CPU. The following iterators are similar to |
| * for_each_*_cpu() iterators but also considers the unbound gcwq. |
| * |
| * for_each_gcwq_cpu() : possible CPUs + WORK_CPU_UNBOUND |
| * for_each_online_gcwq_cpu() : online CPUs + WORK_CPU_UNBOUND |
| * for_each_cwq_cpu() : possible CPUs for bound workqueues, |
| * WORK_CPU_UNBOUND for unbound workqueues |
| */ |
| #define for_each_gcwq_cpu(cpu) \ |
| for ((cpu) = __next_gcwq_cpu(-1, cpu_possible_mask, 3); \ |
| (cpu) < WORK_CPU_NONE; \ |
| (cpu) = __next_gcwq_cpu((cpu), cpu_possible_mask, 3)) |
| |
| #define for_each_online_gcwq_cpu(cpu) \ |
| for ((cpu) = __next_gcwq_cpu(-1, cpu_online_mask, 3); \ |
| (cpu) < WORK_CPU_NONE; \ |
| (cpu) = __next_gcwq_cpu((cpu), cpu_online_mask, 3)) |
| |
| #define for_each_cwq_cpu(cpu, wq) \ |
| for ((cpu) = __next_wq_cpu(-1, cpu_possible_mask, (wq)); \ |
| (cpu) < WORK_CPU_NONE; \ |
| (cpu) = __next_wq_cpu((cpu), cpu_possible_mask, (wq))) |
| |
| #ifdef CONFIG_DEBUG_OBJECTS_WORK |
| |
| static struct debug_obj_descr work_debug_descr; |
| |
| /* |
| * fixup_init is called when: |
| * - an active object is initialized |
| */ |
| static int work_fixup_init(void *addr, enum debug_obj_state state) |
| { |
| struct work_struct *work = addr; |
| |
| switch (state) { |
| case ODEBUG_STATE_ACTIVE: |
| cancel_work_sync(work); |
| debug_object_init(work, &work_debug_descr); |
| return 1; |
| default: |
| return 0; |
| } |
| } |
| |
| /* |
| * fixup_activate is called when: |
| * - an active object is activated |
| * - an unknown object is activated (might be a statically initialized object) |
| */ |
| static int work_fixup_activate(void *addr, enum debug_obj_state state) |
| { |
| struct work_struct *work = addr; |
| |
| switch (state) { |
| |
| case ODEBUG_STATE_NOTAVAILABLE: |
| /* |
| * This is not really a fixup. The work struct was |
| * statically initialized. We just make sure that it |
| * is tracked in the object tracker. |
| */ |
| if (test_bit(WORK_STRUCT_STATIC_BIT, work_data_bits(work))) { |
| debug_object_init(work, &work_debug_descr); |
| debug_object_activate(work, &work_debug_descr); |
| return 0; |
| } |
| WARN_ON_ONCE(1); |
| return 0; |
| |
| case ODEBUG_STATE_ACTIVE: |
| WARN_ON(1); |
| |
| default: |
| return 0; |
| } |
| } |
| |
| /* |
| * fixup_free is called when: |
| * - an active object is freed |
| */ |
| static int work_fixup_free(void *addr, enum debug_obj_state state) |
| { |
| struct work_struct *work = addr; |
| |
| switch (state) { |
| case ODEBUG_STATE_ACTIVE: |
| cancel_work_sync(work); |
| debug_object_free(work, &work_debug_descr); |
| return 1; |
| default: |
| return 0; |
| } |
| } |
| |
| static struct debug_obj_descr work_debug_descr = { |
| .name = "work_struct", |
| .fixup_init = work_fixup_init, |
| .fixup_activate = work_fixup_activate, |
| .fixup_free = work_fixup_free, |
| }; |
| |
| static inline void debug_work_activate(struct work_struct *work) |
| { |
| debug_object_activate(work, &work_debug_descr); |
| } |
| |
| static inline void debug_work_deactivate(struct work_struct *work) |
| { |
| debug_object_deactivate(work, &work_debug_descr); |
| } |
| |
| void __init_work(struct work_struct *work, int onstack) |
| { |
| if (onstack) |
| debug_object_init_on_stack(work, &work_debug_descr); |
| else |
| debug_object_init(work, &work_debug_descr); |
| } |
| EXPORT_SYMBOL_GPL(__init_work); |
| |
| void destroy_work_on_stack(struct work_struct *work) |
| { |
| debug_object_free(work, &work_debug_descr); |
| } |
| EXPORT_SYMBOL_GPL(destroy_work_on_stack); |
| |
| #else |
| static inline void debug_work_activate(struct work_struct *work) { } |
| static inline void debug_work_deactivate(struct work_struct *work) { } |
| #endif |
| |
| /* Serializes the accesses to the list of workqueues. */ |
| static DEFINE_SPINLOCK(workqueue_lock); |
| static LIST_HEAD(workqueues); |
| static bool workqueue_freezing; /* W: have wqs started freezing? */ |
| |
| /* |
| * The almighty global cpu workqueues. nr_running is the only field |
| * which is expected to be used frequently by other cpus via |
| * try_to_wake_up(). Put it in a separate cacheline. |
| */ |
| static DEFINE_PER_CPU(struct global_cwq, global_cwq); |
| static DEFINE_PER_CPU_SHARED_ALIGNED(atomic_t, gcwq_nr_running); |
| |
| /* |
| * Global cpu workqueue and nr_running counter for unbound gcwq. The |
| * gcwq is always online, has GCWQ_DISASSOCIATED set, and all its |
| * workers have WORKER_UNBOUND set. |
| */ |
| static struct global_cwq unbound_global_cwq; |
| static atomic_t unbound_gcwq_nr_running = ATOMIC_INIT(0); /* always 0 */ |
| |
| static int worker_thread(void *__worker); |
| |
| static struct global_cwq *get_gcwq(unsigned int cpu) |
| { |
| if (cpu != WORK_CPU_UNBOUND) |
| return &per_cpu(global_cwq, cpu); |
| else |
| return &unbound_global_cwq; |
| } |
| |
| static atomic_t *get_gcwq_nr_running(unsigned int cpu) |
| { |
| if (cpu != WORK_CPU_UNBOUND) |
| return &per_cpu(gcwq_nr_running, cpu); |
| else |
| return &unbound_gcwq_nr_running; |
| } |
| |
| static struct cpu_workqueue_struct *get_cwq(unsigned int cpu, |
| struct workqueue_struct *wq) |
| { |
| if (!(wq->flags & WQ_UNBOUND)) { |
| if (likely(cpu < nr_cpu_ids)) { |
| #ifdef CONFIG_SMP |
| return per_cpu_ptr(wq->cpu_wq.pcpu, cpu); |
| #else |
| return wq->cpu_wq.single; |
| #endif |
| } |
| } else if (likely(cpu == WORK_CPU_UNBOUND)) |
| return wq->cpu_wq.single; |
| return NULL; |
| } |
| |
| static unsigned int work_color_to_flags(int color) |
| { |
| return color << WORK_STRUCT_COLOR_SHIFT; |
| } |
| |
| static int get_work_color(struct work_struct *work) |
| { |
| return (*work_data_bits(work) >> WORK_STRUCT_COLOR_SHIFT) & |
| ((1 << WORK_STRUCT_COLOR_BITS) - 1); |
| } |
| |
| static int work_next_color(int color) |
| { |
| return (color + 1) % WORK_NR_COLORS; |
| } |
| |
| /* |
| * A work's data points to the cwq with WORK_STRUCT_CWQ set while the |
| * work is on queue. Once execution starts, WORK_STRUCT_CWQ is |
| * cleared and the work data contains the cpu number it was last on. |
| * |
| * set_work_{cwq|cpu}() and clear_work_data() can be used to set the |
| * cwq, cpu or clear work->data. These functions should only be |
| * called while the work is owned - ie. while the PENDING bit is set. |
| * |
| * get_work_[g]cwq() can be used to obtain the gcwq or cwq |
| * corresponding to a work. gcwq is available once the work has been |
| * queued anywhere after initialization. cwq is available only from |
| * queueing until execution starts. |
| */ |
| static inline void set_work_data(struct work_struct *work, unsigned long data, |
| unsigned long flags) |
| { |
| BUG_ON(!work_pending(work)); |
| atomic_long_set(&work->data, data | flags | work_static(work)); |
| } |
| |
| static void set_work_cwq(struct work_struct *work, |
| struct cpu_workqueue_struct *cwq, |
| unsigned long extra_flags) |
| { |
| set_work_data(work, (unsigned long)cwq, |
| WORK_STRUCT_PENDING | WORK_STRUCT_CWQ | extra_flags); |
| } |
| |
| static void set_work_cpu(struct work_struct *work, unsigned int cpu) |
| { |
| set_work_data(work, cpu << WORK_STRUCT_FLAG_BITS, WORK_STRUCT_PENDING); |
| } |
| |
| static void clear_work_data(struct work_struct *work) |
| { |
| set_work_data(work, WORK_STRUCT_NO_CPU, 0); |
| } |
| |
| static struct cpu_workqueue_struct *get_work_cwq(struct work_struct *work) |
| { |
| unsigned long data = atomic_long_read(&work->data); |
| |
| if (data & WORK_STRUCT_CWQ) |
| return (void *)(data & WORK_STRUCT_WQ_DATA_MASK); |
| else |
| return NULL; |
| } |
| |
| static struct global_cwq *get_work_gcwq(struct work_struct *work) |
| { |
| unsigned long data = atomic_long_read(&work->data); |
| unsigned int cpu; |
| |
| if (data & WORK_STRUCT_CWQ) |
| return ((struct cpu_workqueue_struct *) |
| (data & WORK_STRUCT_WQ_DATA_MASK))->gcwq; |
| |
| cpu = data >> WORK_STRUCT_FLAG_BITS; |
| if (cpu == WORK_CPU_NONE) |
| return NULL; |
| |
| BUG_ON(cpu >= nr_cpu_ids && cpu != WORK_CPU_UNBOUND); |
| return get_gcwq(cpu); |
| } |
| |
| /* |
| * Policy functions. These define the policies on how the global |
| * worker pool is managed. Unless noted otherwise, these functions |
| * assume that they're being called with gcwq->lock held. |
| */ |
| |
| static bool __need_more_worker(struct global_cwq *gcwq) |
| { |
| return !atomic_read(get_gcwq_nr_running(gcwq->cpu)) || |
| gcwq->flags & GCWQ_HIGHPRI_PENDING; |
| } |
| |
| /* |
| * Need to wake up a worker? Called from anything but currently |
| * running workers. |
| */ |
| static bool need_more_worker(struct global_cwq *gcwq) |
| { |
| return !list_empty(&gcwq->worklist) && __need_more_worker(gcwq); |
| } |
| |
| /* Can I start working? Called from busy but !running workers. */ |
| static bool may_start_working(struct global_cwq *gcwq) |
| { |
| return gcwq->nr_idle; |
| } |
| |
| /* Do I need to keep working? Called from currently running workers. */ |
| static bool keep_working(struct global_cwq *gcwq) |
| { |
| atomic_t *nr_running = get_gcwq_nr_running(gcwq->cpu); |
| |
| return !list_empty(&gcwq->worklist) && |
| (atomic_read(nr_running) <= 1 || |
| gcwq->flags & GCWQ_HIGHPRI_PENDING); |
| } |
| |
| /* Do we need a new worker? Called from manager. */ |
| static bool need_to_create_worker(struct global_cwq *gcwq) |
| { |
| return need_more_worker(gcwq) && !may_start_working(gcwq); |
| } |
| |
| /* Do I need to be the manager? */ |
| static bool need_to_manage_workers(struct global_cwq *gcwq) |
| { |
| return need_to_create_worker(gcwq) || gcwq->flags & GCWQ_MANAGE_WORKERS; |
| } |
| |
| /* Do we have too many workers and should some go away? */ |
| static bool too_many_workers(struct global_cwq *gcwq) |
| { |
| bool managing = gcwq->flags & GCWQ_MANAGING_WORKERS; |
| int nr_idle = gcwq->nr_idle + managing; /* manager is considered idle */ |
| int nr_busy = gcwq->nr_workers - nr_idle; |
| |
| return nr_idle > 2 && (nr_idle - 2) * MAX_IDLE_WORKERS_RATIO >= nr_busy; |
| } |
| |
| /* |
| * Wake up functions. |
| */ |
| |
| /* Return the first worker. Safe with preemption disabled */ |
| static struct worker *first_worker(struct global_cwq *gcwq) |
| { |
| if (unlikely(list_empty(&gcwq->idle_list))) |
| return NULL; |
| |
| return list_first_entry(&gcwq->idle_list, struct worker, entry); |
| } |
| |
| /** |
| * wake_up_worker - wake up an idle worker |
| * @gcwq: gcwq to wake worker for |
| * |
| * Wake up the first idle worker of @gcwq. |
| * |
| * CONTEXT: |
| * spin_lock_irq(gcwq->lock). |
| */ |
| static void wake_up_worker(struct global_cwq *gcwq) |
| { |
| struct worker *worker = first_worker(gcwq); |
| |
| if (likely(worker)) |
| wake_up_process(worker->task); |
| } |
| |
| /** |
| * wq_worker_waking_up - a worker is waking up |
| * @task: task waking up |
| * @cpu: CPU @task is waking up to |
| * |
| * This function is called during try_to_wake_up() when a worker is |
| * being awoken. |
| * |
| * CONTEXT: |
| * spin_lock_irq(rq->lock) |
| */ |
| void wq_worker_waking_up(struct task_struct *task, unsigned int cpu) |
| { |
| struct worker *worker = kthread_data(task); |
| |
| if (!(worker->flags & WORKER_NOT_RUNNING)) |
| atomic_inc(get_gcwq_nr_running(cpu)); |
| } |
| |
| /** |
| * wq_worker_sleeping - a worker is going to sleep |
| * @task: task going to sleep |
| * @cpu: CPU in question, must be the current CPU number |
| * |
| * This function is called during schedule() when a busy worker is |
| * going to sleep. Worker on the same cpu can be woken up by |
| * returning pointer to its task. |
| * |
| * CONTEXT: |
| * spin_lock_irq(rq->lock) |
| * |
| * RETURNS: |
| * Worker task on @cpu to wake up, %NULL if none. |
| */ |
| struct task_struct *wq_worker_sleeping(struct task_struct *task, |
| unsigned int cpu) |
| { |
| struct worker *worker = kthread_data(task), *to_wakeup = NULL; |
| struct global_cwq *gcwq = get_gcwq(cpu); |
| atomic_t *nr_running = get_gcwq_nr_running(cpu); |
| |
| if (worker->flags & WORKER_NOT_RUNNING) |
| return NULL; |
| |
| /* this can only happen on the local cpu */ |
| BUG_ON(cpu != raw_smp_processor_id()); |
| |
| /* |
| * The counterpart of the following dec_and_test, implied mb, |
| * worklist not empty test sequence is in insert_work(). |
| * Please read comment there. |
| * |
| * NOT_RUNNING is clear. This means that trustee is not in |
| * charge and we're running on the local cpu w/ rq lock held |
| * and preemption disabled, which in turn means that none else |
| * could be manipulating idle_list, so dereferencing idle_list |
| * without gcwq lock is safe. |
| */ |
| if (atomic_dec_and_test(nr_running) && !list_empty(&gcwq->worklist)) |
| to_wakeup = first_worker(gcwq); |
| return to_wakeup ? to_wakeup->task : NULL; |
| } |
| |
| /** |
| * worker_set_flags - set worker flags and adjust nr_running accordingly |
| * @worker: self |
| * @flags: flags to set |
| * @wakeup: wakeup an idle worker if necessary |
| * |
| * Set @flags in @worker->flags and adjust nr_running accordingly. If |
| * nr_running becomes zero and @wakeup is %true, an idle worker is |
| * woken up. |
| * |
| * CONTEXT: |
| * spin_lock_irq(gcwq->lock) |
| */ |
| static inline void worker_set_flags(struct worker *worker, unsigned int flags, |
| bool wakeup) |
| { |
| struct global_cwq *gcwq = worker->gcwq; |
| |
| WARN_ON_ONCE(worker->task != current); |
| |
| /* |
| * If transitioning into NOT_RUNNING, adjust nr_running and |
| * wake up an idle worker as necessary if requested by |
| * @wakeup. |
| */ |
| if ((flags & WORKER_NOT_RUNNING) && |
| !(worker->flags & WORKER_NOT_RUNNING)) { |
| atomic_t *nr_running = get_gcwq_nr_running(gcwq->cpu); |
| |
| if (wakeup) { |
| if (atomic_dec_and_test(nr_running) && |
| !list_empty(&gcwq->worklist)) |
| wake_up_worker(gcwq); |
| } else |
| atomic_dec(nr_running); |
| } |
| |
| worker->flags |= flags; |
| } |
| |
| /** |
| * worker_clr_flags - clear worker flags and adjust nr_running accordingly |
| * @worker: self |
| * @flags: flags to clear |
| * |
| * Clear @flags in @worker->flags and adjust nr_running accordingly. |
| * |
| * CONTEXT: |
| * spin_lock_irq(gcwq->lock) |
| */ |
| static inline void worker_clr_flags(struct worker *worker, unsigned int flags) |
| { |
| struct global_cwq *gcwq = worker->gcwq; |
| unsigned int oflags = worker->flags; |
| |
| WARN_ON_ONCE(worker->task != current); |
| |
| worker->flags &= ~flags; |
| |
| /* |
| * If transitioning out of NOT_RUNNING, increment nr_running. Note |
| * that the nested NOT_RUNNING is not a noop. NOT_RUNNING is mask |
| * of multiple flags, not a single flag. |
| */ |
| if ((flags & WORKER_NOT_RUNNING) && (oflags & WORKER_NOT_RUNNING)) |
| if (!(worker->flags & WORKER_NOT_RUNNING)) |
| atomic_inc(get_gcwq_nr_running(gcwq->cpu)); |
| } |
| |
| /** |
| * busy_worker_head - return the busy hash head for a work |
| * @gcwq: gcwq of interest |
| * @work: work to be hashed |
| * |
| * Return hash head of @gcwq for @work. |
| * |
| * CONTEXT: |
| * spin_lock_irq(gcwq->lock). |
| * |
| * RETURNS: |
| * Pointer to the hash head. |
| */ |
| static struct hlist_head *busy_worker_head(struct global_cwq *gcwq, |
| struct work_struct *work) |
| { |
| const int base_shift = ilog2(sizeof(struct work_struct)); |
| unsigned long v = (unsigned long)work; |
| |
| /* simple shift and fold hash, do we need something better? */ |
| v >>= base_shift; |
| v += v >> BUSY_WORKER_HASH_ORDER; |
| v &= BUSY_WORKER_HASH_MASK; |
| |
| return &gcwq->busy_hash[v]; |
| } |
| |
| /** |
| * __find_worker_executing_work - find worker which is executing a work |
| * @gcwq: gcwq of interest |
| * @bwh: hash head as returned by busy_worker_head() |
| * @work: work to find worker for |
| * |
| * Find a worker which is executing @work on @gcwq. @bwh should be |
| * the hash head obtained by calling busy_worker_head() with the same |
| * work. |
| * |
| * CONTEXT: |
| * spin_lock_irq(gcwq->lock). |
| * |
| * RETURNS: |
| * Pointer to worker which is executing @work if found, NULL |
| * otherwise. |
| */ |
| static struct worker *__find_worker_executing_work(struct global_cwq *gcwq, |
| struct hlist_head *bwh, |
| struct work_struct *work) |
| { |
| struct worker *worker; |
| struct hlist_node *tmp; |
| |
| hlist_for_each_entry(worker, tmp, bwh, hentry) |
| if (worker->current_work == work) |
| return worker; |
| return NULL; |
| } |
| |
| /** |
| * find_worker_executing_work - find worker which is executing a work |
| * @gcwq: gcwq of interest |
| * @work: work to find worker for |
| * |
| * Find a worker which is executing @work on @gcwq. This function is |
| * identical to __find_worker_executing_work() except that this |
| * function calculates @bwh itself. |
| * |
| * CONTEXT: |
| * spin_lock_irq(gcwq->lock). |
| * |
| * RETURNS: |
| * Pointer to worker which is executing @work if found, NULL |
| * otherwise. |
| */ |
| static struct worker *find_worker_executing_work(struct global_cwq *gcwq, |
| struct work_struct *work) |
| { |
| return __find_worker_executing_work(gcwq, busy_worker_head(gcwq, work), |
| work); |
| } |
| |
| /** |
| * gcwq_determine_ins_pos - find insertion position |
| * @gcwq: gcwq of interest |
| * @cwq: cwq a work is being queued for |
| * |
| * A work for @cwq is about to be queued on @gcwq, determine insertion |
| * position for the work. If @cwq is for HIGHPRI wq, the work is |
| * queued at the head of the queue but in FIFO order with respect to |
| * other HIGHPRI works; otherwise, at the end of the queue. This |
| * function also sets GCWQ_HIGHPRI_PENDING flag to hint @gcwq that |
| * there are HIGHPRI works pending. |
| * |
| * CONTEXT: |
| * spin_lock_irq(gcwq->lock). |
| * |
| * RETURNS: |
| * Pointer to inserstion position. |
| */ |
| static inline struct list_head *gcwq_determine_ins_pos(struct global_cwq *gcwq, |
| struct cpu_workqueue_struct *cwq) |
| { |
| struct work_struct *twork; |
| |
| if (likely(!(cwq->wq->flags & WQ_HIGHPRI))) |
| return &gcwq->worklist; |
| |
| list_for_each_entry(twork, &gcwq->worklist, entry) { |
| struct cpu_workqueue_struct *tcwq = get_work_cwq(twork); |
| |
| if (!(tcwq->wq->flags & WQ_HIGHPRI)) |
| break; |
| } |
| |
| gcwq->flags |= GCWQ_HIGHPRI_PENDING; |
| return &twork->entry; |
| } |
| |
| /** |
| * insert_work - insert a work into gcwq |
| * @cwq: cwq @work belongs to |
| * @work: work to insert |
| * @head: insertion point |
| * @extra_flags: extra WORK_STRUCT_* flags to set |
| * |
| * Insert @work which belongs to @cwq into @gcwq after @head. |
| * @extra_flags is or'd to work_struct flags. |
| * |
| * CONTEXT: |
| * spin_lock_irq(gcwq->lock). |
| */ |
| static void insert_work(struct cpu_workqueue_struct *cwq, |
| struct work_struct *work, struct list_head *head, |
| unsigned int extra_flags) |
| { |
| struct global_cwq *gcwq = cwq->gcwq; |
| |
| /* we own @work, set data and link */ |
| set_work_cwq(work, cwq, extra_flags); |
| |
| /* |
| * Ensure that we get the right work->data if we see the |
| * result of list_add() below, see try_to_grab_pending(). |
| */ |
| smp_wmb(); |
| |
| list_add_tail(&work->entry, head); |
| |
| /* |
| * Ensure either worker_sched_deactivated() sees the above |
| * list_add_tail() or we see zero nr_running to avoid workers |
| * lying around lazily while there are works to be processed. |
| */ |
| smp_mb(); |
| |
| if (__need_more_worker(gcwq)) |
| wake_up_worker(gcwq); |
| } |
| |
| /* |
| * Test whether @work is being queued from another work executing on the |
| * same workqueue. This is rather expensive and should only be used from |
| * cold paths. |
| */ |
| static bool is_chained_work(struct workqueue_struct *wq) |
| { |
| unsigned long flags; |
| unsigned int cpu; |
| |
| for_each_gcwq_cpu(cpu) { |
| struct global_cwq *gcwq = get_gcwq(cpu); |
| struct worker *worker; |
| struct hlist_node *pos; |
| int i; |
| |
| spin_lock_irqsave(&gcwq->lock, flags); |
| for_each_busy_worker(worker, i, pos, gcwq) { |
| if (worker->task != current) |
| continue; |
| spin_unlock_irqrestore(&gcwq->lock, flags); |
| /* |
| * I'm @worker, no locking necessary. See if @work |
| * is headed to the same workqueue. |
| */ |
| return worker->current_cwq->wq == wq; |
| } |
| spin_unlock_irqrestore(&gcwq->lock, flags); |
| } |
| return false; |
| } |
| |
| static void __queue_work(unsigned int cpu, struct workqueue_struct *wq, |
| struct work_struct *work) |
| { |
| struct global_cwq *gcwq; |
| struct cpu_workqueue_struct *cwq; |
| struct list_head *worklist; |
| unsigned int work_flags; |
| unsigned long flags; |
| |
| debug_work_activate(work); |
| |
| /* if dying, only works from the same workqueue are allowed */ |
| if (unlikely(wq->flags & WQ_DYING) && |
| WARN_ON_ONCE(!is_chained_work(wq))) |
| return; |
| |
| /* determine gcwq to use */ |
| if (!(wq->flags & WQ_UNBOUND)) { |
| struct global_cwq *last_gcwq; |
| |
| if (unlikely(cpu == WORK_CPU_UNBOUND)) |
| cpu = raw_smp_processor_id(); |
| |
| /* |
| * It's multi cpu. If @wq is non-reentrant and @work |
| * was previously on a different cpu, it might still |
| * be running there, in which case the work needs to |
| * be queued on that cpu to guarantee non-reentrance. |
| */ |
| gcwq = get_gcwq(cpu); |
| if (wq->flags & WQ_NON_REENTRANT && |
| (last_gcwq = get_work_gcwq(work)) && last_gcwq != gcwq) { |
| struct worker *worker; |
| |
| spin_lock_irqsave(&last_gcwq->lock, flags); |
| |
| worker = find_worker_executing_work(last_gcwq, work); |
| |
| if (worker && worker->current_cwq->wq == wq) |
| gcwq = last_gcwq; |
| else { |
| /* meh... not running there, queue here */ |
| spin_unlock_irqrestore(&last_gcwq->lock, flags); |
| spin_lock_irqsave(&gcwq->lock, flags); |
| } |
| } else |
| spin_lock_irqsave(&gcwq->lock, flags); |
| } else { |
| gcwq = get_gcwq(WORK_CPU_UNBOUND); |
| spin_lock_irqsave(&gcwq->lock, flags); |
| } |
| |
| /* gcwq determined, get cwq and queue */ |
| cwq = get_cwq(gcwq->cpu, wq); |
| trace_workqueue_queue_work(cpu, cwq, work); |
| |
| BUG_ON(!list_empty(&work->entry)); |
| |
| cwq->nr_in_flight[cwq->work_color]++; |
| work_flags = work_color_to_flags(cwq->work_color); |
| |
| if (likely(cwq->nr_active < cwq->max_active)) { |
| trace_workqueue_activate_work(work); |
| cwq->nr_active++; |
| worklist = gcwq_determine_ins_pos(gcwq, cwq); |
| } else { |
| work_flags |= WORK_STRUCT_DELAYED; |
| worklist = &cwq->delayed_works; |
| } |
| |
| insert_work(cwq, work, worklist, work_flags); |
| |
| spin_unlock_irqrestore(&gcwq->lock, flags); |
| } |
| |
| /** |
| * queue_work - queue work on a workqueue |
| * @wq: workqueue to use |
| * @work: work to queue |
| * |
| * Returns 0 if @work was already on a queue, non-zero otherwise. |
| * |
| * We queue the work to the CPU on which it was submitted, but if the CPU dies |
| * it can be processed by another CPU. |
| */ |
| int queue_work(struct workqueue_struct *wq, struct work_struct *work) |
| { |
| int ret; |
| |
| ret = queue_work_on(get_cpu(), wq, work); |
| put_cpu(); |
| |
| return ret; |
| } |
| EXPORT_SYMBOL_GPL(queue_work); |
| |
| /** |
| * queue_work_on - queue work on specific cpu |
| * @cpu: CPU number to execute work on |
| * @wq: workqueue to use |
| * @work: work to queue |
| * |
| * Returns 0 if @work was already on a queue, non-zero otherwise. |
| * |
| * We queue the work to a specific CPU, the caller must ensure it |
| * can't go away. |
| */ |
| int |
| queue_work_on(int cpu, struct workqueue_struct *wq, struct work_struct *work) |
| { |
| int ret = 0; |
| |
| if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { |
| __queue_work(cpu, wq, work); |
| ret = 1; |
| } |
| return ret; |
| } |
| EXPORT_SYMBOL_GPL(queue_work_on); |
| |
| static void delayed_work_timer_fn(unsigned long __data) |
| { |
| struct delayed_work *dwork = (struct delayed_work *)__data; |
| struct cpu_workqueue_struct *cwq = get_work_cwq(&dwork->work); |
| |
| __queue_work(smp_processor_id(), cwq->wq, &dwork->work); |
| } |
| |
| /** |
| * queue_delayed_work - queue work on a workqueue after delay |
| * @wq: workqueue to use |
| * @dwork: delayable work to queue |
| * @delay: number of jiffies to wait before queueing |
| * |
| * Returns 0 if @work was already on a queue, non-zero otherwise. |
| */ |
| int queue_delayed_work(struct workqueue_struct *wq, |
| struct delayed_work *dwork, unsigned long delay) |
| { |
| if (delay == 0) |
| return queue_work(wq, &dwork->work); |
| |
| return queue_delayed_work_on(-1, wq, dwork, delay); |
| } |
| EXPORT_SYMBOL_GPL(queue_delayed_work); |
| |
| /** |
| * queue_delayed_work_on - queue work on specific CPU after delay |
| * @cpu: CPU number to execute work on |
| * @wq: workqueue to use |
| * @dwork: work to queue |
| * @delay: number of jiffies to wait before queueing |
| * |
| * Returns 0 if @work was already on a queue, non-zero otherwise. |
| */ |
| int queue_delayed_work_on(int cpu, struct workqueue_struct *wq, |
| struct delayed_work *dwork, unsigned long delay) |
| { |
| int ret = 0; |
| struct timer_list *timer = &dwork->timer; |
| struct work_struct *work = &dwork->work; |
| |
| if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { |
| unsigned int lcpu; |
| |
| BUG_ON(timer_pending(timer)); |
| BUG_ON(!list_empty(&work->entry)); |
| |
| timer_stats_timer_set_start_info(&dwork->timer); |
| |
| /* |
| * This stores cwq for the moment, for the timer_fn. |
| * Note that the work's gcwq is preserved to allow |
| * reentrance detection for delayed works. |
| */ |
| if (!(wq->flags & WQ_UNBOUND)) { |
| struct global_cwq *gcwq = get_work_gcwq(work); |
| |
| if (gcwq && gcwq->cpu != WORK_CPU_UNBOUND) |
| lcpu = gcwq->cpu; |
| else |
| lcpu = raw_smp_processor_id(); |
| } else |
| lcpu = WORK_CPU_UNBOUND; |
| |
| set_work_cwq(work, get_cwq(lcpu, wq), 0); |
| |
| timer->expires = jiffies + delay; |
| timer->data = (unsigned long)dwork; |
| timer->function = delayed_work_timer_fn; |
| |
| if (unlikely(cpu >= 0)) |
| add_timer_on(timer, cpu); |
| else |
| add_timer(timer); |
| ret = 1; |
| } |
| return ret; |
| } |
| EXPORT_SYMBOL_GPL(queue_delayed_work_on); |
| |
| /** |
| * worker_enter_idle - enter idle state |
| * @worker: worker which is entering idle state |
| * |
| * @worker is entering idle state. Update stats and idle timer if |
| * necessary. |
| * |
| * LOCKING: |
| * spin_lock_irq(gcwq->lock). |
| */ |
| static void worker_enter_idle(struct worker *worker) |
| { |
| struct global_cwq *gcwq = worker->gcwq; |
| |
| BUG_ON(worker->flags & WORKER_IDLE); |
| BUG_ON(!list_empty(&worker->entry) && |
| (worker->hentry.next || worker->hentry.pprev)); |
| |
| /* can't use worker_set_flags(), also called from start_worker() */ |
| worker->flags |= WORKER_IDLE; |
| gcwq->nr_idle++; |
| worker->last_active = jiffies; |
| |
| /* idle_list is LIFO */ |
| list_add(&worker->entry, &gcwq->idle_list); |
| |
| if (likely(!(worker->flags & WORKER_ROGUE))) { |
| if (too_many_workers(gcwq) && !timer_pending(&gcwq->idle_timer)) |
| mod_timer(&gcwq->idle_timer, |
| jiffies + IDLE_WORKER_TIMEOUT); |
| } else |
| wake_up_all(&gcwq->trustee_wait); |
| |
| /* sanity check nr_running */ |
| WARN_ON_ONCE(gcwq->nr_workers == gcwq->nr_idle && |
| atomic_read(get_gcwq_nr_running(gcwq->cpu))); |
| } |
| |
| /** |
| * worker_leave_idle - leave idle state |
| * @worker: worker which is leaving idle state |
| * |
| * @worker is leaving idle state. Update stats. |
| * |
| * LOCKING: |
| * spin_lock_irq(gcwq->lock). |
| */ |
| static void worker_leave_idle(struct worker *worker) |
| { |
| struct global_cwq *gcwq = worker->gcwq; |
| |
| BUG_ON(!(worker->flags & WORKER_IDLE)); |
| worker_clr_flags(worker, WORKER_IDLE); |
| gcwq->nr_idle--; |
| list_del_init(&worker->entry); |
| } |
| |
| /** |
| * worker_maybe_bind_and_lock - bind worker to its cpu if possible and lock gcwq |
| * @worker: self |
| * |
| * Works which are scheduled while the cpu is online must at least be |
| * scheduled to a worker which is bound to the cpu so that if they are |
| * flushed from cpu callbacks while cpu is going down, they are |
| * guaranteed to execute on the cpu. |
| * |
| * This function is to be used by rogue workers and rescuers to bind |
| * themselves to the target cpu and may race with cpu going down or |
| * coming online. kthread_bind() can't be used because it may put the |
| * worker to already dead cpu and set_cpus_allowed_ptr() can't be used |
| * verbatim as it's best effort and blocking and gcwq may be |
| * [dis]associated in the meantime. |
| * |
| * This function tries set_cpus_allowed() and locks gcwq and verifies |
| * the binding against GCWQ_DISASSOCIATED which is set during |
| * CPU_DYING and cleared during CPU_ONLINE, so if the worker enters |
| * idle state or fetches works without dropping lock, it can guarantee |
| * the scheduling requirement described in the first paragraph. |
| * |
| * CONTEXT: |
| * Might sleep. Called without any lock but returns with gcwq->lock |
| * held. |
| * |
| * RETURNS: |
| * %true if the associated gcwq is online (@worker is successfully |
| * bound), %false if offline. |
| */ |
| static bool worker_maybe_bind_and_lock(struct worker *worker) |
| __acquires(&gcwq->lock) |
| { |
| struct global_cwq *gcwq = worker->gcwq; |
| struct task_struct *task = worker->task; |
| |
| while (true) { |
| /* |
| * The following call may fail, succeed or succeed |
| * without actually migrating the task to the cpu if |
| * it races with cpu hotunplug operation. Verify |
| * against GCWQ_DISASSOCIATED. |
| */ |
| if (!(gcwq->flags & GCWQ_DISASSOCIATED)) |
| set_cpus_allowed_ptr(task, get_cpu_mask(gcwq->cpu)); |
| |
| spin_lock_irq(&gcwq->lock); |
| if (gcwq->flags & GCWQ_DISASSOCIATED) |
| return false; |
| if (task_cpu(task) == gcwq->cpu && |
| cpumask_equal(¤t->cpus_allowed, |
| get_cpu_mask(gcwq->cpu))) |
| return true; |
| spin_unlock_irq(&gcwq->lock); |
| |
| /* CPU has come up inbetween, retry migration */ |
| cpu_relax(); |
| } |
| } |
| |
| /* |
| * Function for worker->rebind_work used to rebind rogue busy workers |
| * to the associated cpu which is coming back online. This is |
| * scheduled by cpu up but can race with other cpu hotplug operations |
| * and may be executed twice without intervening cpu down. |
| */ |
| static void worker_rebind_fn(struct work_struct *work) |
| { |
| struct worker *worker = container_of(work, struct worker, rebind_work); |
| struct global_cwq *gcwq = worker->gcwq; |
| |
| if (worker_maybe_bind_and_lock(worker)) |
| worker_clr_flags(worker, WORKER_REBIND); |
| |
| spin_unlock_irq(&gcwq->lock); |
| } |
| |
| static struct worker *alloc_worker(void) |
| { |
| struct worker *worker; |
| |
| worker = kzalloc(sizeof(*worker), GFP_KERNEL); |
| if (worker) { |
| INIT_LIST_HEAD(&worker->entry); |
| INIT_LIST_HEAD(&worker->scheduled); |
| INIT_WORK(&worker->rebind_work, worker_rebind_fn); |
| /* on creation a worker is in !idle && prep state */ |
| worker->flags = WORKER_PREP; |
| } |
| return worker; |
| } |
| |
| /** |
| * create_worker - create a new workqueue worker |
| * @gcwq: gcwq the new worker will belong to |
| * @bind: whether to set affinity to @cpu or not |
| * |
| * Create a new worker which is bound to @gcwq. The returned worker |
| * can be started by calling start_worker() or destroyed using |
| * destroy_worker(). |
| * |
| * CONTEXT: |
| * Might sleep. Does GFP_KERNEL allocations. |
| * |
| * RETURNS: |
| * Pointer to the newly created worker. |
| */ |
| static struct worker *create_worker(struct global_cwq *gcwq, bool bind) |
| { |
| bool on_unbound_cpu = gcwq->cpu == WORK_CPU_UNBOUND; |
| struct worker *worker = NULL; |
| int id = -1; |
| |
| spin_lock_irq(&gcwq->lock); |
| while (ida_get_new(&gcwq->worker_ida, &id)) { |
| spin_unlock_irq(&gcwq->lock); |
| if (!ida_pre_get(&gcwq->worker_ida, GFP_KERNEL)) |
| goto fail; |
| spin_lock_irq(&gcwq->lock); |
| } |
| spin_unlock_irq(&gcwq->lock); |
| |
| worker = alloc_worker(); |
| if (!worker) |
| goto fail; |
| |
| worker->gcwq = gcwq; |
| worker->id = id; |
| |
| if (!on_unbound_cpu) |
| worker->task = kthread_create(worker_thread, worker, |
| "kworker/%u:%d", gcwq->cpu, id); |
| else |
| worker->task = kthread_create(worker_thread, worker, |
| "kworker/u:%d", id); |
| if (IS_ERR(worker->task)) |
| goto fail; |
| |
| /* |
| * A rogue worker will become a regular one if CPU comes |
| * online later on. Make sure every worker has |
| * PF_THREAD_BOUND set. |
| */ |
| if (bind && !on_unbound_cpu) |
| kthread_bind(worker->task, gcwq->cpu); |
| else { |
| worker->task->flags |= PF_THREAD_BOUND; |
| if (on_unbound_cpu) |
| worker->flags |= WORKER_UNBOUND; |
| } |
| |
| return worker; |
| fail: |
| if (id >= 0) { |
| spin_lock_irq(&gcwq->lock); |
| ida_remove(&gcwq->worker_ida, id); |
| spin_unlock_irq(&gcwq->lock); |
| } |
| kfree(worker); |
| return NULL; |
| } |
| |
| /** |
| * start_worker - start a newly created worker |
| * @worker: worker to start |
| * |
| * Make the gcwq aware of @worker and start it. |
| * |
| * CONTEXT: |
| * spin_lock_irq(gcwq->lock). |
| */ |
| static void start_worker(struct worker *worker) |
| { |
| worker->flags |= WORKER_STARTED; |
| worker->gcwq->nr_workers++; |
| worker_enter_idle(worker); |
| wake_up_process(worker->task); |
| } |
| |
| /** |
| * destroy_worker - destroy a workqueue worker |
| * @worker: worker to be destroyed |
| * |
| * Destroy @worker and adjust @gcwq stats accordingly. |
| * |
| * CONTEXT: |
| * spin_lock_irq(gcwq->lock) which is released and regrabbed. |
| */ |
| static void destroy_worker(struct worker *worker) |
| { |
| struct global_cwq *gcwq = worker->gcwq; |
| int id = worker->id; |
| |
| /* sanity check frenzy */ |
| BUG_ON(worker->current_work); |
| BUG_ON(!list_empty(&worker->scheduled)); |
| |
| if (worker->flags & WORKER_STARTED) |
| gcwq->nr_workers--; |
| if (worker->flags & WORKER_IDLE) |
| gcwq->nr_idle--; |
| |
| list_del_init(&worker->entry); |
| worker->flags |= WORKER_DIE; |
| |
| spin_unlock_irq(&gcwq->lock); |
| |
| kthread_stop(worker->task); |
| kfree(worker); |
| |
| spin_lock_irq(&gcwq->lock); |
| ida_remove(&gcwq->worker_ida, id); |
| } |
| |
| static void idle_worker_timeout(unsigned long __gcwq) |
| { |
| struct global_cwq *gcwq = (void *)__gcwq; |
| |
| spin_lock_irq(&gcwq->lock); |
| |
| if (too_many_workers(gcwq)) { |
| struct worker *worker; |
| unsigned long expires; |
| |
| /* idle_list is kept in LIFO order, check the last one */ |
| worker = list_entry(gcwq->idle_list.prev, struct worker, entry); |
| expires = worker->last_active + IDLE_WORKER_TIMEOUT; |
| |
| if (time_before(jiffies, expires)) |
| mod_timer(&gcwq->idle_timer, expires); |
| else { |
| /* it's been idle for too long, wake up manager */ |
| gcwq->flags |= GCWQ_MANAGE_WORKERS; |
| wake_up_worker(gcwq); |
| } |
| } |
| |
| spin_unlock_irq(&gcwq->lock); |
| } |
| |
| static bool send_mayday(struct work_struct *work) |
| { |
| struct cpu_workqueue_struct *cwq = get_work_cwq(work); |
| struct workqueue_struct *wq = cwq->wq; |
| unsigned int cpu; |
| |
| if (!(wq->flags & WQ_RESCUER)) |
| return false; |
| |
| /* mayday mayday mayday */ |
| cpu = cwq->gcwq->cpu; |
| /* WORK_CPU_UNBOUND can't be set in cpumask, use cpu 0 instead */ |
| if (cpu == WORK_CPU_UNBOUND) |
| cpu = 0; |
| if (!mayday_test_and_set_cpu(cpu, wq->mayday_mask)) |
| wake_up_process(wq->rescuer->task); |
| return true; |
| } |
| |
| static void gcwq_mayday_timeout(unsigned long __gcwq) |
| { |
| struct global_cwq *gcwq = (void *)__gcwq; |
| struct work_struct *work; |
| |
| spin_lock_irq(&gcwq->lock); |
| |
| if (need_to_create_worker(gcwq)) { |
| /* |
| * We've been trying to create a new worker but |
| * haven't been successful. We might be hitting an |
| * allocation deadlock. Send distress signals to |
| * rescuers. |
| */ |
| list_for_each_entry(work, &gcwq->worklist, entry) |
| send_mayday(work); |
| } |
| |
| spin_unlock_irq(&gcwq->lock); |
| |
| mod_timer(&gcwq->mayday_timer, jiffies + MAYDAY_INTERVAL); |
| } |
| |
| /** |
| * maybe_create_worker - create a new worker if necessary |
| * @gcwq: gcwq to create a new worker for |
| * |
| * Create a new worker for @gcwq if necessary. @gcwq is guaranteed to |
| * have at least one idle worker on return from this function. If |
| * creating a new worker takes longer than MAYDAY_INTERVAL, mayday is |
| * sent to all rescuers with works scheduled on @gcwq to resolve |
| * possible allocation deadlock. |
| * |
| * On return, need_to_create_worker() is guaranteed to be false and |
| * may_start_working() true. |
| * |
| * LOCKING: |
| * spin_lock_irq(gcwq->lock) which may be released and regrabbed |
| * multiple times. Does GFP_KERNEL allocations. Called only from |
| * manager. |
| * |
| * RETURNS: |
| * false if no action was taken and gcwq->lock stayed locked, true |
| * otherwise. |
| */ |
| static bool maybe_create_worker(struct global_cwq *gcwq) |
| __releases(&gcwq->lock) |
| __acquires(&gcwq->lock) |
| { |
| if (!need_to_create_worker(gcwq)) |
| return false; |
| restart: |
| spin_unlock_irq(&gcwq->lock); |
| |
| /* if we don't make progress in MAYDAY_INITIAL_TIMEOUT, call for help */ |
| mod_timer(&gcwq->mayday_timer, jiffies + MAYDAY_INITIAL_TIMEOUT); |
| |
| while (true) { |
| struct worker *worker; |
| |
| worker = create_worker(gcwq, true); |
| if (worker) { |
| del_timer_sync(&gcwq->mayday_timer); |
| spin_lock_irq(&gcwq->lock); |
| start_worker(worker); |
| BUG_ON(need_to_create_worker(gcwq)); |
| return true; |
| } |
| |
| if (!need_to_create_worker(gcwq)) |
| break; |
| |
| __set_current_state(TASK_INTERRUPTIBLE); |
| schedule_timeout(CREATE_COOLDOWN); |
| |
| if (!need_to_create_worker(gcwq)) |
| break; |
| } |
| |
| del_timer_sync(&gcwq->mayday_timer); |
| spin_lock_irq(&gcwq->lock); |
| if (need_to_create_worker(gcwq)) |
| goto restart; |
| return true; |
| } |
| |
| /** |
| * maybe_destroy_worker - destroy workers which have been idle for a while |
| * @gcwq: gcwq to destroy workers for |
| * |
| * Destroy @gcwq workers which have been idle for longer than |
| * IDLE_WORKER_TIMEOUT. |
| * |
| * LOCKING: |
| * spin_lock_irq(gcwq->lock) which may be released and regrabbed |
| * multiple times. Called only from manager. |
| * |
| * RETURNS: |
| * false if no action was taken and gcwq->lock stayed locked, true |
| * otherwise. |
| */ |
| static bool maybe_destroy_workers(struct global_cwq *gcwq) |
| { |
| bool ret = false; |
| |
| while (too_many_workers(gcwq)) { |
| struct worker *worker; |
| unsigned long expires; |
| |
| worker = list_entry(gcwq->idle_list.prev, struct worker, entry); |
| expires = worker->last_active + IDLE_WORKER_TIMEOUT; |
| |
| if (time_before(jiffies, expires)) { |
| mod_timer(&gcwq->idle_timer, expires); |
| break; |
| } |
| |
| destroy_worker(worker); |
| ret = true; |
| } |
| |
| return ret; |
| } |
| |
| /** |
| * manage_workers - manage worker pool |
| * @worker: self |
| * |
| * Assume the manager role and manage gcwq worker pool @worker belongs |
| * to. At any given time, there can be only zero or one manager per |
| * gcwq. The exclusion is handled automatically by this function. |
| * |
| * The caller can safely start processing works on false return. On |
| * true return, it's guaranteed that need_to_create_worker() is false |
| * and may_start_working() is true. |
| * |
| * CONTEXT: |
| * spin_lock_irq(gcwq->lock) which may be released and regrabbed |
| * multiple times. Does GFP_KERNEL allocations. |
| * |
| * RETURNS: |
| * false if no action was taken and gcwq->lock stayed locked, true if |
| * some action was taken. |
| */ |
| static bool manage_workers(struct worker *worker) |
| { |
| struct global_cwq *gcwq = worker->gcwq; |
| bool ret = false; |
| |
| if (gcwq->flags & GCWQ_MANAGING_WORKERS) |
| return ret; |
| |
| gcwq->flags &= ~GCWQ_MANAGE_WORKERS; |
| gcwq->flags |= GCWQ_MANAGING_WORKERS; |
| |
| /* |
| * Destroy and then create so that may_start_working() is true |
| * on return. |
| */ |
| ret |= maybe_destroy_workers(gcwq); |
| ret |= maybe_create_worker(gcwq); |
| |
| gcwq->flags &= ~GCWQ_MANAGING_WORKERS; |
| |
| /* |
| * The trustee might be waiting to take over the manager |
| * position, tell it we're done. |
| */ |
| if (unlikely(gcwq->trustee)) |
| wake_up_all(&gcwq->trustee_wait); |
| |
| return ret; |
| } |
| |
| /** |
| * move_linked_works - move linked works to a list |
| * @work: start of series of works to be scheduled |
| * @head: target list to append @work to |
| * @nextp: out paramter for nested worklist walking |
| * |
| * Schedule linked works starting from @work to @head. Work series to |
| * be scheduled starts at @work and includes any consecutive work with |
| * WORK_STRUCT_LINKED set in its predecessor. |
| * |
| * If @nextp is not NULL, it's updated to point to the next work of |
| * the last scheduled work. This allows move_linked_works() to be |
| * nested inside outer list_for_each_entry_safe(). |
| * |
| * CONTEXT: |
| * spin_lock_irq(gcwq->lock). |
| */ |
| static void move_linked_works(struct work_struct *work, struct list_head *head, |
| struct work_struct **nextp) |
| { |
| struct work_struct *n; |
| |
| /* |
| * Linked worklist will always end before the end of the list, |
| * use NULL for list head. |
| */ |
| list_for_each_entry_safe_from(work, n, NULL, entry) { |
| list_move_tail(&work->entry, head); |
| if (!(*work_data_bits(work) & WORK_STRUCT_LINKED)) |
| break; |
| } |
| |
| /* |
| * If we're already inside safe list traversal and have moved |
| * multiple works to the scheduled queue, the next position |
| * needs to be updated. |
| */ |
| if (nextp) |
| *nextp = n; |
| } |
| |
| static void cwq_activate_first_delayed(struct cpu_workqueue_struct *cwq) |
| { |
| struct work_struct *work = list_first_entry(&cwq->delayed_works, |
| struct work_struct, entry); |
| struct list_head *pos = gcwq_determine_ins_pos(cwq->gcwq, cwq); |
| |
| trace_workqueue_activate_work(work); |
| move_linked_works(work, pos, NULL); |
| __clear_bit(WORK_STRUCT_DELAYED_BIT, work_data_bits(work)); |
| cwq->nr_active++; |
| } |
| |
| /** |
| * cwq_dec_nr_in_flight - decrement cwq's nr_in_flight |
| * @cwq: cwq of interest |
| * @color: color of work which left the queue |
| * @delayed: for a delayed work |
| * |
| * A work either has completed or is removed from pending queue, |
| * decrement nr_in_flight of its cwq and handle workqueue flushing. |
| * |
| * CONTEXT: |
| * spin_lock_irq(gcwq->lock). |
| */ |
| static void cwq_dec_nr_in_flight(struct cpu_workqueue_struct *cwq, int color, |
| bool delayed) |
| { |
| /* ignore uncolored works */ |
| if (color == WORK_NO_COLOR) |
| return; |
| |
| cwq->nr_in_flight[color]--; |
| |
| if (!delayed) { |
| cwq->nr_active--; |
| if (!list_empty(&cwq->delayed_works)) { |
| /* one down, submit a delayed one */ |
| if (cwq->nr_active < cwq->max_active) |
| cwq_activate_first_delayed(cwq); |
| } |
| } |
| |
| /* is flush in progress and are we at the flushing tip? */ |
| if (likely(cwq->flush_color != color)) |
| return; |
| |
| /* are there still in-flight works? */ |
| if (cwq->nr_in_flight[color]) |
| return; |
| |
| /* this cwq is done, clear flush_color */ |
| cwq->flush_color = -1; |
| |
| /* |
| * If this was the last cwq, wake up the first flusher. It |
| * will handle the rest. |
| */ |
| if (atomic_dec_and_test(&cwq->wq->nr_cwqs_to_flush)) |
| complete(&cwq->wq->first_flusher->done); |
| } |
| |
| /** |
| * process_one_work - process single work |
| * @worker: self |
| * @work: work to process |
| * |
| * Process @work. This function contains all the logics necessary to |
| * process a single work including synchronization against and |
| * interaction with other workers on the same cpu, queueing and |
| * flushing. As long as context requirement is met, any worker can |
| * call this function to process a work. |
| * |
| * CONTEXT: |
| * spin_lock_irq(gcwq->lock) which is released and regrabbed. |
| */ |
| static void process_one_work(struct worker *worker, struct work_struct *work) |
| __releases(&gcwq->lock) |
| __acquires(&gcwq->lock) |
| { |
| struct cpu_workqueue_struct *cwq = get_work_cwq(work); |
| struct global_cwq *gcwq = cwq->gcwq; |
| struct hlist_head *bwh = busy_worker_head(gcwq, work); |
| bool cpu_intensive = cwq->wq->flags & WQ_CPU_INTENSIVE; |
| work_func_t f = work->func; |
| int work_color; |
| struct worker *collision; |
| #ifdef CONFIG_LOCKDEP |
| /* |
| * It is permissible to free the struct work_struct from |
| * inside the function that is called from it, this we need to |
| * take into account for lockdep too. To avoid bogus "held |
| * lock freed" warnings as well as problems when looking into |
| * work->lockdep_map, make a copy and use that here. |
| */ |
| struct lockdep_map lockdep_map = work->lockdep_map; |
| #endif |
| /* |
| * A single work shouldn't be executed concurrently by |
| * multiple workers on a single cpu. Check whether anyone is |
| * already processing the work. If so, defer the work to the |
| * currently executing one. |
| */ |
| collision = __find_worker_executing_work(gcwq, bwh, work); |
| if (unlikely(collision)) { |
| move_linked_works(work, &collision->scheduled, NULL); |
| return; |
| } |
| |
| /* claim and process */ |
| debug_work_deactivate(work); |
| hlist_add_head(&worker->hentry, bwh); |
| worker->current_work = work; |
| worker->current_cwq = cwq; |
| work_color = get_work_color(work); |
| |
| /* record the current cpu number in the work data and dequeue */ |
| set_work_cpu(work, gcwq->cpu); |
| list_del_init(&work->entry); |
| |
| /* |
| * If HIGHPRI_PENDING, check the next work, and, if HIGHPRI, |
| * wake up another worker; otherwise, clear HIGHPRI_PENDING. |
| */ |
| if (unlikely(gcwq->flags & GCWQ_HIGHPRI_PENDING)) { |
| struct work_struct *nwork = list_first_entry(&gcwq->worklist, |
| struct work_struct, entry); |
| |
| if (!list_empty(&gcwq->worklist) && |
| get_work_cwq(nwork)->wq->flags & WQ_HIGHPRI) |
| wake_up_worker(gcwq); |
| else |
| gcwq->flags &= ~GCWQ_HIGHPRI_PENDING; |
| } |
| |
| /* |
| * CPU intensive works don't participate in concurrency |
| * management. They're the scheduler's responsibility. |
| */ |
| if (unlikely(cpu_intensive)) |
| worker_set_flags(worker, WORKER_CPU_INTENSIVE, true); |
| |
| spin_unlock_irq(&gcwq->lock); |
| |
| work_clear_pending(work); |
| lock_map_acquire_read(&cwq->wq->lockdep_map); |
| lock_map_acquire(&lockdep_map); |
| trace_workqueue_execute_start(work); |
| f(work); |
| /* |
| * While we must be careful to not use "work" after this, the trace |
| * point will only record its address. |
| */ |
| trace_workqueue_execute_end(work); |
| lock_map_release(&lockdep_map); |
| lock_map_release(&cwq->wq->lockdep_map); |
| |
| if (unlikely(in_atomic() || lockdep_depth(current) > 0)) { |
| printk(KERN_ERR "BUG: workqueue leaked lock or atomic: " |
| "%s/0x%08x/%d\n", |
| current->comm, preempt_count(), task_pid_nr(current)); |
| printk(KERN_ERR " last function: "); |
| print_symbol("%s\n", (unsigned long)f); |
| debug_show_held_locks(current); |
| dump_stack(); |
| } |
| |
| spin_lock_irq(&gcwq->lock); |
| |
| /* clear cpu intensive status */ |
| if (unlikely(cpu_intensive)) |
| worker_clr_flags(worker, WORKER_CPU_INTENSIVE); |
| |
| /* we're done with it, release */ |
| hlist_del_init(&worker->hentry); |
| worker->current_work = NULL; |
| worker->current_cwq = NULL; |
| cwq_dec_nr_in_flight(cwq, work_color, false); |
| } |
| |
| /** |
| * process_scheduled_works - process scheduled works |
| * @worker: self |
| * |
| * Process all scheduled works. Please note that the scheduled list |
| * may change while processing a work, so this function repeatedly |
| * fetches a work from the top and executes it. |
| * |
| * CONTEXT: |
| * spin_lock_irq(gcwq->lock) which may be released and regrabbed |
| * multiple times. |
| */ |
| static void process_scheduled_works(struct worker *worker) |
| { |
| while (!list_empty(&worker->scheduled)) { |
| struct work_struct *work = list_first_entry(&worker->scheduled, |
| struct work_struct, entry); |
| process_one_work(worker, work); |
| } |
| } |
| |
| /** |
| * worker_thread - the worker thread function |
| * @__worker: self |
| * |
| * The gcwq worker thread function. There's a single dynamic pool of |
| * these per each cpu. These workers process all works regardless of |
| * their specific target workqueue. The only exception is works which |
| * belong to workqueues with a rescuer which will be explained in |
| * rescuer_thread(). |
| */ |
| static int worker_thread(void *__worker) |
| { |
| struct worker *worker = __worker; |
| struct global_cwq *gcwq = worker->gcwq; |
| |
| /* tell the scheduler that this is a workqueue worker */ |
| worker->task->flags |= PF_WQ_WORKER; |
| woke_up: |
| spin_lock_irq(&gcwq->lock); |
| |
| /* DIE can be set only while we're idle, checking here is enough */ |
| if (worker->flags & WORKER_DIE) { |
| spin_unlock_irq(&gcwq->lock); |
| worker->task->flags &= ~PF_WQ_WORKER; |
| return 0; |
| } |
| |
| worker_leave_idle(worker); |
| recheck: |
| /* no more worker necessary? */ |
| if (!need_more_worker(gcwq)) |
| goto sleep; |
| |
| /* do we need to manage? */ |
| if (unlikely(!may_start_working(gcwq)) && manage_workers(worker)) |
| goto recheck; |
| |
| /* |
| * ->scheduled list can only be filled while a worker is |
| * preparing to process a work or actually processing it. |
| * Make sure nobody diddled with it while I was sleeping. |
| */ |
| BUG_ON(!list_empty(&worker->scheduled)); |
| |
| /* |
| * When control reaches this point, we're guaranteed to have |
| * at least one idle worker or that someone else has already |
| * assumed the manager role. |
| */ |
| worker_clr_flags(worker, WORKER_PREP); |
| |
| do { |
| struct work_struct *work = |
| list_first_entry(&gcwq->worklist, |
| struct work_struct, entry); |
| |
| if (likely(!(*work_data_bits(work) & WORK_STRUCT_LINKED))) { |
| /* optimization path, not strictly necessary */ |
| process_one_work(worker, work); |
| if (unlikely(!list_empty(&worker->scheduled))) |
| process_scheduled_works(worker); |
| } else { |
| move_linked_works(work, &worker->scheduled, NULL); |
| process_scheduled_works(worker); |
| } |
| } while (keep_working(gcwq)); |
| |
| worker_set_flags(worker, WORKER_PREP, false); |
| sleep: |
| if (unlikely(need_to_manage_workers(gcwq)) && manage_workers(worker)) |
| goto recheck; |
| |
| /* |
| * gcwq->lock is held and there's no work to process and no |
| * need to manage, sleep. Workers are woken up only while |
| * holding gcwq->lock or from local cpu, so setting the |
| * current state before releasing gcwq->lock is enough to |
| * prevent losing any event. |
| */ |
| worker_enter_idle(worker); |
| __set_current_state(TASK_INTERRUPTIBLE); |
| spin_unlock_irq(&gcwq->lock); |
| schedule(); |
| goto woke_up; |
| } |
| |
| /** |
| * rescuer_thread - the rescuer thread function |
| * @__wq: the associated workqueue |
| * |
| * Workqueue rescuer thread function. There's one rescuer for each |
| * workqueue which has WQ_RESCUER set. |
| * |
| * Regular work processing on a gcwq may block trying to create a new |
| * worker which uses GFP_KERNEL allocation which has slight chance of |
| * developing into deadlock if some works currently on the same queue |
| * need to be processed to satisfy the GFP_KERNEL allocation. This is |
| * the problem rescuer solves. |
| * |
| * When such condition is possible, the gcwq summons rescuers of all |
| * workqueues which have works queued on the gcwq and let them process |
| * those works so that forward progress can be guaranteed. |
| * |
| * This should happen rarely. |
| */ |
| static int rescuer_thread(void *__wq) |
| { |
| struct workqueue_struct *wq = __wq; |
| struct worker *rescuer = wq->rescuer; |
| struct list_head *scheduled = &rescuer->scheduled; |
| bool is_unbound = wq->flags & WQ_UNBOUND; |
| unsigned int cpu; |
| |
| set_user_nice(current, RESCUER_NICE_LEVEL); |
| repeat: |
| set_current_state(TASK_INTERRUPTIBLE); |
| |
| if (kthread_should_stop()) |
| return 0; |
| |
| /* |
| * See whether any cpu is asking for help. Unbounded |
| * workqueues use cpu 0 in mayday_mask for CPU_UNBOUND. |
| */ |
| for_each_mayday_cpu(cpu, wq->mayday_mask) { |
| unsigned int tcpu = is_unbound ? WORK_CPU_UNBOUND : cpu; |
| struct cpu_workqueue_struct *cwq = get_cwq(tcpu, wq); |
| struct global_cwq *gcwq = cwq->gcwq; |
| struct work_struct *work, *n; |
| |
| __set_current_state(TASK_RUNNING); |
| mayday_clear_cpu(cpu, wq->mayday_mask); |
| |
| /* migrate to the target cpu if possible */ |
| rescuer->gcwq = gcwq; |
| worker_maybe_bind_and_lock(rescuer); |
| |
| /* |
| * Slurp in all works issued via this workqueue and |
| * process'em. |
| */ |
| BUG_ON(!list_empty(&rescuer->scheduled)); |
| list_for_each_entry_safe(work, n, &gcwq->worklist, entry) |
| if (get_work_cwq(work) == cwq) |
| move_linked_works(work, scheduled, &n); |
| |
| process_scheduled_works(rescuer); |
| |
| /* |
| * Leave this gcwq. If keep_working() is %true, notify a |
| * regular worker; otherwise, we end up with 0 concurrency |
| * and stalling the execution. |
| */ |
| if (keep_working(gcwq)) |
| wake_up_worker(gcwq); |
| |
| spin_unlock_irq(&gcwq->lock); |
| } |
| |
| schedule(); |
| goto repeat; |
| } |
| |
| struct wq_barrier { |
| struct work_struct work; |
| struct completion done; |
| }; |
| |
| static void wq_barrier_func(struct work_struct *work) |
| { |
| struct wq_barrier *barr = container_of(work, struct wq_barrier, work); |
| complete(&barr->done); |
| } |
| |
| /** |
| * insert_wq_barrier - insert a barrier work |
| * @cwq: cwq to insert barrier into |
| * @barr: wq_barrier to insert |
| * @target: target work to attach @barr to |
| * @worker: worker currently executing @target, NULL if @target is not executing |
| * |
| * @barr is linked to @target such that @barr is completed only after |
| * @target finishes execution. Please note that the ordering |
| * guarantee is observed only with respect to @target and on the local |
| * cpu. |
| * |
| * Currently, a queued barrier can't be canceled. This is because |
| * try_to_grab_pending() can't determine whether the work to be |
| * grabbed is at the head of the queue and thus can't clear LINKED |
| * flag of the previous work while there must be a valid next work |
| * after a work with LINKED flag set. |
| * |
| * Note that when @worker is non-NULL, @target may be modified |
| * underneath us, so we can't reliably determine cwq from @target. |
| * |
| * CONTEXT: |
| * spin_lock_irq(gcwq->lock). |
| */ |
| static void insert_wq_barrier(struct cpu_workqueue_struct *cwq, |
| struct wq_barrier *barr, |
| struct work_struct *target, struct worker *worker) |
| { |
| struct list_head *head; |
| unsigned int linked = 0; |
| |
| /* |
| * debugobject calls are safe here even with gcwq->lock locked |
| * as we know for sure that this will not trigger any of the |
| * checks and call back into the fixup functions where we |
| * might deadlock. |
| */ |
| INIT_WORK_ONSTACK(&barr->work, wq_barrier_func); |
| __set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(&barr->work)); |
| init_completion(&barr->done); |
| |
| /* |
| * If @target is currently being executed, schedule the |
| * barrier to the worker; otherwise, put it after @target. |
| */ |
| if (worker) |
| head = worker->scheduled.next; |
| else { |
| unsigned long *bits = work_data_bits(target); |
| |
| head = target->entry.next; |
| /* there can already be other linked works, inherit and set */ |
| linked = *bits & WORK_STRUCT_LINKED; |
| __set_bit(WORK_STRUCT_LINKED_BIT, bits); |
| } |
| |
| debug_work_activate(&barr->work); |
| insert_work(cwq, &barr->work, head, |
| work_color_to_flags(WORK_NO_COLOR) | linked); |
| } |
| |
| /** |
| * flush_workqueue_prep_cwqs - prepare cwqs for workqueue flushing |
| * @wq: workqueue being flushed |
| * @flush_color: new flush color, < 0 for no-op |
| * @work_color: new work color, < 0 for no-op |
| * |
| * Prepare cwqs for workqueue flushing. |
| * |
| * If @flush_color is non-negative, flush_color on all cwqs should be |
| * -1. If no cwq has in-flight commands at the specified color, all |
| * cwq->flush_color's stay at -1 and %false is returned. If any cwq |
| * has in flight commands, its cwq->flush_color is set to |
| * @flush_color, @wq->nr_cwqs_to_flush is updated accordingly, cwq |
| * wakeup logic is armed and %true is returned. |
| * |
| * The caller should have initialized @wq->first_flusher prior to |
| * calling this function with non-negative @flush_color. If |
| * @flush_color is negative, no flush color update is done and %false |
| * is returned. |
| * |
| * If @work_color is non-negative, all cwqs should have the same |
| * work_color which is previous to @work_color and all will be |
| * advanced to @work_color. |
| * |
| * CONTEXT: |
| * mutex_lock(wq->flush_mutex). |
| * |
| * RETURNS: |
| * %true if @flush_color >= 0 and there's something to flush. %false |
| * otherwise. |
| */ |
| static bool flush_workqueue_prep_cwqs(struct workqueue_struct *wq, |
| int flush_color, int work_color) |
| { |
| bool wait = false; |
| unsigned int cpu; |
| |
| if (flush_color >= 0) { |
| BUG_ON(atomic_read(&wq->nr_cwqs_to_flush)); |
| atomic_set(&wq->nr_cwqs_to_flush, 1); |
| } |
| |
| for_each_cwq_cpu(cpu, wq) { |
| struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); |
| struct global_cwq *gcwq = cwq->gcwq; |
| |
| spin_lock_irq(&gcwq->lock); |
| |
| if (flush_color >= 0) { |
| BUG_ON(cwq->flush_color != -1); |
| |
| if (cwq->nr_in_flight[flush_color]) { |
| cwq->flush_color = flush_color; |
| atomic_inc(&wq->nr_cwqs_to_flush); |
| wait = true; |
| } |
| } |
| |
| if (work_color >= 0) { |
| BUG_ON(work_color != work_next_color(cwq->work_color)); |
| cwq->work_color = work_color; |
| } |
| |
| spin_unlock_irq(&gcwq->lock); |
| } |
| |
| if (flush_color >= 0 && atomic_dec_and_test(&wq->nr_cwqs_to_flush)) |
| complete(&wq->first_flusher->done); |
| |
| return wait; |
| } |
| |
| /** |
| * flush_workqueue - ensure that any scheduled work has run to completion. |
| * @wq: workqueue to flush |
| * |
| * Forces execution of the workqueue and blocks until its completion. |
| * This is typically used in driver shutdown handlers. |
| * |
| * We sleep until all works which were queued on entry have been handled, |
| * but we are not livelocked by new incoming ones. |
| */ |
| void flush_workqueue(struct workqueue_struct *wq) |
| { |
| struct wq_flusher this_flusher = { |
| .list = LIST_HEAD_INIT(this_flusher.list), |
| .flush_color = -1, |
| .done = COMPLETION_INITIALIZER_ONSTACK(this_flusher.done), |
| }; |
| int next_color; |
| |
| lock_map_acquire(&wq->lockdep_map); |
| lock_map_release(&wq->lockdep_map); |
| |
| mutex_lock(&wq->flush_mutex); |
| |
| /* |
| * Start-to-wait phase |
| */ |
| next_color = work_next_color(wq->work_color); |
| |
| if (next_color != wq->flush_color) { |
| /* |
| * Color space is not full. The current work_color |
| * becomes our flush_color and work_color is advanced |
| * by one. |
| */ |
| BUG_ON(!list_empty(&wq->flusher_overflow)); |
| this_flusher.flush_color = wq->work_color; |
| wq->work_color = next_color; |
| |
| if (!wq->first_flusher) { |
| /* no flush in progress, become the first flusher */ |
| BUG_ON(wq->flush_color != this_flusher.flush_color); |
| |
| wq->first_flusher = &this_flusher; |
| |
| if (!flush_workqueue_prep_cwqs(wq, wq->flush_color, |
| wq->work_color)) { |
| /* nothing to flush, done */ |
| wq->flush_color = next_color; |
| wq->first_flusher = NULL; |
| goto out_unlock; |
| } |
| } else { |
| /* wait in queue */ |
| BUG_ON(wq->flush_color == this_flusher.flush_color); |
| list_add_tail(&this_flusher.list, &wq->flusher_queue); |
| flush_workqueue_prep_cwqs(wq, -1, wq->work_color); |
| } |
| } else { |
| /* |
| * Oops, color space is full, wait on overflow queue. |
| * The next flush completion will assign us |
| * flush_color and transfer to flusher_queue. |
| */ |
| list_add_tail(&this_flusher.list, &wq->flusher_overflow); |
| } |
| |
| mutex_unlock(&wq->flush_mutex); |
| |
| wait_for_completion(&this_flusher.done); |
| |
| /* |
| * Wake-up-and-cascade phase |
| * |
| * First flushers are responsible for cascading flushes and |
| * handling overflow. Non-first flushers can simply return. |
| */ |
| if (wq->first_flusher != &this_flusher) |
| return; |
| |
| mutex_lock(&wq->flush_mutex); |
| |
| /* we might have raced, check again with mutex held */ |
| if (wq->first_flusher != &this_flusher) |
| goto out_unlock; |
| |
| wq->first_flusher = NULL; |
| |
| BUG_ON(!list_empty(&this_flusher.list)); |
| BUG_ON(wq->flush_color != this_flusher.flush_color); |
| |
| while (true) { |
| struct wq_flusher *next, *tmp; |
| |
| /* complete all the flushers sharing the current flush color */ |
| list_for_each_entry_safe(next, tmp, &wq->flusher_queue, list) { |
| if (next->flush_color != wq->flush_color) |
| break; |
| list_del_init(&next->list); |
| complete(&next->done); |
| } |
| |
| BUG_ON(!list_empty(&wq->flusher_overflow) && |
| wq->flush_color != work_next_color(wq->work_color)); |
| |
| /* this flush_color is finished, advance by one */ |
| wq->flush_color = work_next_color(wq->flush_color); |
| |
| /* one color has been freed, handle overflow queue */ |
| if (!list_empty(&wq->flusher_overflow)) { |
| /* |
| * Assign the same color to all overflowed |
| * flushers, advance work_color and append to |
| * flusher_queue. This is the start-to-wait |
| * phase for these overflowed flushers. |
| */ |
| list_for_each_entry(tmp, &wq->flusher_overflow, list) |
| tmp->flush_color = wq->work_color; |
| |
| wq->work_color = work_next_color(wq->work_color); |
| |
| list_splice_tail_init(&wq->flusher_overflow, |
| &wq->flusher_queue); |
| flush_workqueue_prep_cwqs(wq, -1, wq->work_color); |
| } |
| |
| if (list_empty(&wq->flusher_queue)) { |
| BUG_ON(wq->flush_color != wq->work_color); |
| break; |
| } |
| |
| /* |
| * Need to flush more colors. Make the next flusher |
| * the new first flusher and arm cwqs. |
| */ |
| BUG_ON(wq->flush_color == wq->work_color); |
| BUG_ON(wq->flush_color != next->flush_color); |
| |
| list_del_init(&next->list); |
| wq->first_flusher = next; |
| |
| if (flush_workqueue_prep_cwqs(wq, wq->flush_color, -1)) |
| break; |
| |
| /* |
| * Meh... this color is already done, clear first |
| * flusher and repeat cascading. |
| */ |
| wq->first_flusher = NULL; |
| } |
| |
| out_unlock: |
| mutex_unlock(&wq->flush_mutex); |
| } |
| EXPORT_SYMBOL_GPL(flush_workqueue); |
| |
| static bool start_flush_work(struct work_struct *work, struct wq_barrier *barr, |
| bool wait_executing) |
| { |
| struct worker *worker = NULL; |
| struct global_cwq *gcwq; |
| struct cpu_workqueue_struct *cwq; |
| |
| might_sleep(); |
| gcwq = get_work_gcwq(work); |
| if (!gcwq) |
| return false; |
| |
| spin_lock_irq(&gcwq->lock); |
| if (!list_empty(&work->entry)) { |
| /* |
| * See the comment near try_to_grab_pending()->smp_rmb(). |
| * If it was re-queued to a different gcwq under us, we |
| * are not going to wait. |
| */ |
| smp_rmb(); |
| cwq = get_work_cwq(work); |
| if (unlikely(!cwq || gcwq != cwq->gcwq)) |
| goto already_gone; |
| } else if (wait_executing) { |
| worker = find_worker_executing_work(gcwq, work); |
| if (!worker) |
| goto already_gone; |
| cwq = worker->current_cwq; |
| } else |
| goto already_gone; |
| |
| insert_wq_barrier(cwq, barr, work, worker); |
| spin_unlock_irq(&gcwq->lock); |
| |
| /* |
| * If @max_active is 1 or rescuer is in use, flushing another work |
| * item on the same workqueue may lead to deadlock. Make sure the |
| * flusher is not running on the same workqueue by verifying write |
| * access. |
| */ |
| if (cwq->wq->saved_max_active == 1 || cwq->wq->flags & WQ_RESCUER) |
| lock_map_acquire(&cwq->wq->lockdep_map); |
| else |
| lock_map_acquire_read(&cwq->wq->lockdep_map); |
| lock_map_release(&cwq->wq->lockdep_map); |
| |
| return true; |
| already_gone: |
| spin_unlock_irq(&gcwq->lock); |
| return false; |
| } |
| |
| /** |
| * flush_work - wait for a work to finish executing the last queueing instance |
| * @work: the work to flush |
| * |
| * Wait until @work has finished execution. This function considers |
| * only the last queueing instance of @work. If @work has been |
| * enqueued across different CPUs on a non-reentrant workqueue or on |
| * multiple workqueues, @work might still be executing on return on |
| * some of the CPUs from earlier queueing. |
| * |
| * If @work was queued only on a non-reentrant, ordered or unbound |
| * workqueue, @work is guaranteed to be idle on return if it hasn't |
| * been requeued since flush started. |
| * |
| * RETURNS: |
| * %true if flush_work() waited for the work to finish execution, |
| * %false if it was already idle. |
| */ |
| bool flush_work(struct work_struct *work) |
| { |
| struct wq_barrier barr; |
| |
| if (start_flush_work(work, &barr, true)) { |
| wait_for_completion(&barr.done); |
| destroy_work_on_stack(&barr.work); |
| return true; |
| } else |
| return false; |
| } |
| EXPORT_SYMBOL_GPL(flush_work); |
| |
| static bool wait_on_cpu_work(struct global_cwq *gcwq, struct work_struct *work) |
| { |
| struct wq_barrier barr; |
| struct worker *worker; |
| |
| spin_lock_irq(&gcwq->lock); |
| |
| worker = find_worker_executing_work(gcwq, work); |
| if (unlikely(worker)) |
| insert_wq_barrier(worker->current_cwq, &barr, work, worker); |
| |
| spin_unlock_irq(&gcwq->lock); |
| |
| if (unlikely(worker)) { |
| wait_for_completion(&barr.done); |
| destroy_work_on_stack(&barr.work); |
| return true; |
| } else |
| return false; |
| } |
| |
| static bool wait_on_work(struct work_struct *work) |
| { |
| bool ret = false; |
| int cpu; |
| |
| might_sleep(); |
| |
| lock_map_acquire(&work->lockdep_map); |
| lock_map_release(&work->lockdep_map); |
| |
| for_each_gcwq_cpu(cpu) |
| ret |= wait_on_cpu_work(get_gcwq(cpu), work); |
| return ret; |
| } |
| |
| /** |
| * flush_work_sync - wait until a work has finished execution |
| * @work: the work to flush |
| * |
| * Wait until @work has finished execution. On return, it's |
| * guaranteed that all queueing instances of @work which happened |
| * before this function is called are finished. In other words, if |
| * @work hasn't been requeued since this function was called, @work is |
| * guaranteed to be idle on return. |
| * |
| * RETURNS: |
| * %true if flush_work_sync() waited for the work to finish execution, |
| * %false if it was already idle. |
| */ |
| bool flush_work_sync(struct work_struct *work) |
| { |
| struct wq_barrier barr; |
| bool pending, waited; |
| |
| /* we'll wait for executions separately, queue barr only if pending */ |
| pending = start_flush_work(work, &barr, false); |
| |
| /* wait for executions to finish */ |
| waited = wait_on_work(work); |
| |
| /* wait for the pending one */ |
| if (pending) { |
| wait_for_completion(&barr.done); |
| destroy_work_on_stack(&barr.work); |
| } |
| |
| return pending || waited; |
| } |
| EXPORT_SYMBOL_GPL(flush_work_sync); |
| |
| /* |
| * Upon a successful return (>= 0), the caller "owns" WORK_STRUCT_PENDING bit, |
| * so this work can't be re-armed in any way. |
| */ |
| static int try_to_grab_pending(struct work_struct *work) |
| { |
| struct global_cwq *gcwq; |
| int ret = -1; |
| |
| if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) |
| return 0; |
| |
| /* |
| * The queueing is in progress, or it is already queued. Try to |
| * steal it from ->worklist without clearing WORK_STRUCT_PENDING. |
| */ |
| gcwq = get_work_gcwq(work); |
| if (!gcwq) |
| return ret; |
| |
| spin_lock_irq(&gcwq->lock); |
| if (!list_empty(&work->entry)) { |
| /* |
| * This work is queued, but perhaps we locked the wrong gcwq. |
| * In that case we must see the new value after rmb(), see |
| * insert_work()->wmb(). |
| */ |
| smp_rmb(); |
| if (gcwq == get_work_gcwq(work)) { |
| debug_work_deactivate(work); |
| list_del_init(&work->entry); |
| cwq_dec_nr_in_flight(get_work_cwq(work), |
| get_work_color(work), |
| *work_data_bits(work) & WORK_STRUCT_DELAYED); |
| ret = 1; |
| } |
| } |
| spin_unlock_irq(&gcwq->lock); |
| |
| return ret; |
| } |
| |
| static bool __cancel_work_timer(struct work_struct *work, |
| struct timer_list* timer) |
| { |
| int ret; |
| |
| do { |
| ret = (timer && likely(del_timer(timer))); |
| if (!ret) |
| ret = try_to_grab_pending(work); |
| wait_on_work(work); |
| } while (unlikely(ret < 0)); |
| |
| clear_work_data(work); |
| return ret; |
| } |
| |
| /** |
| * cancel_work_sync - cancel a work and wait for it to finish |
| * @work: the work to cancel |
| * |
| * Cancel @work and wait for its execution to finish. This function |
| * can be used even if the work re-queues itself or migrates to |
| * another workqueue. On return from this function, @work is |
| * guaranteed to be not pending or executing on any CPU. |
| * |
| * cancel_work_sync(&delayed_work->work) must not be used for |
| * delayed_work's. Use cancel_delayed_work_sync() instead. |
| * |
| * The caller must ensure that the workqueue on which @work was last |
| * queued can't be destroyed before this function returns. |
| * |
| * RETURNS: |
| * %true if @work was pending, %false otherwise. |
| */ |
| bool cancel_work_sync(struct work_struct *work) |
| { |
| return __cancel_work_timer(work, NULL); |
| } |
| EXPORT_SYMBOL_GPL(cancel_work_sync); |
| |
| /** |
| * flush_delayed_work - wait for a dwork to finish executing the last queueing |
| * @dwork: the delayed work to flush |
| * |
| * Delayed timer is cancelled and the pending work is queued for |
| * immediate execution. Like flush_work(), this function only |
| * considers the last queueing instance of @dwork. |
| * |
| * RETURNS: |
| * %true if flush_work() waited for the work to finish execution, |
| * %false if it was already idle. |
| */ |
| bool flush_delayed_work(struct delayed_work *dwork) |
| { |
| if (del_timer_sync(&dwork->timer)) |
| __queue_work(raw_smp_processor_id(), |
| get_work_cwq(&dwork->work)->wq, &dwork->work); |
| return flush_work(&dwork->work); |
| } |
| EXPORT_SYMBOL(flush_delayed_work); |
| |
| /** |
| * flush_delayed_work_sync - wait for a dwork to finish |
| * @dwork: the delayed work to flush |
| * |
| * Delayed timer is cancelled and the pending work is queued for |
| * execution immediately. Other than timer handling, its behavior |
| * is identical to flush_work_sync(). |
| * |
| * RETURNS: |
| * %true if flush_work_sync() waited for the work to finish execution, |
| * %false if it was already idle. |
| */ |
| bool flush_delayed_work_sync(struct delayed_work *dwork) |
| { |
| if (del_timer_sync(&dwork->timer)) |
| __queue_work(raw_smp_processor_id(), |
| get_work_cwq(&dwork->work)->wq, &dwork->work); |
| return flush_work_sync(&dwork->work); |
| } |
| EXPORT_SYMBOL(flush_delayed_work_sync); |
| |
| /** |
| * cancel_delayed_work_sync - cancel a delayed work and wait for it to finish |
| * @dwork: the delayed work cancel |
| * |
| * This is cancel_work_sync() for delayed works. |
| * |
| * RETURNS: |
| * %true if @dwork was pending, %false otherwise. |
| */ |
| bool cancel_delayed_work_sync(struct delayed_work *dwork) |
| { |
| return __cancel_work_timer(&dwork->work, &dwork->timer); |
| } |
| EXPORT_SYMBOL(cancel_delayed_work_sync); |
| |
| /** |
| * schedule_work - put work task in global workqueue |
| * @work: job to be done |
| * |
| * Returns zero if @work was already on the kernel-global workqueue and |
| * non-zero otherwise. |
| * |
| * This puts a job in the kernel-global workqueue if it was not already |
| * queued and leaves it in the same position on the kernel-global |
| * workqueue otherwise. |
| */ |
| int schedule_work(struct work_struct *work) |
| { |
| return queue_work(system_wq, work); |
| } |
| EXPORT_SYMBOL(schedule_work); |
| |
| /* |
| * schedule_work_on - put work task on a specific cpu |
| * @cpu: cpu to put the work task on |
| * @work: job to be done |
| * |
| * This puts a job on a specific cpu |
| */ |
| int schedule_work_on(int cpu, struct work_struct *work) |
| { |
| return queue_work_on(cpu, system_wq, work); |
| } |
| EXPORT_SYMBOL(schedule_work_on); |
| |
| /** |
| * schedule_delayed_work - put work task in global workqueue after delay |
| * @dwork: job to be done |
| * @delay: number of jiffies to wait or 0 for immediate execution |
| * |
| * After waiting for a given time this puts a job in the kernel-global |
| * workqueue. |
| */ |
| int schedule_delayed_work(struct delayed_work *dwork, |
| unsigned long delay) |
| { |
| return queue_delayed_work(system_wq, dwork, delay); |
| } |
| EXPORT_SYMBOL(schedule_delayed_work); |
| |
| /** |
| * schedule_delayed_work_on - queue work in global workqueue on CPU after delay |
| * @cpu: cpu to use |
| * @dwork: job to be done |
| * @delay: number of jiffies to wait |
| * |
| * After waiting for a given time this puts a job in the kernel-global |
| * workqueue on the specified CPU. |
| */ |
| int schedule_delayed_work_on(int cpu, |
| struct delayed_work *dwork, unsigned long delay) |
| { |
| return queue_delayed_work_on(cpu, system_wq, dwork, delay); |
| } |
| EXPORT_SYMBOL(schedule_delayed_work_on); |
| |
| /** |
| * schedule_on_each_cpu - execute a function synchronously on each online CPU |
| * @func: the function to call |
| * |
| * schedule_on_each_cpu() executes @func on each online CPU using the |
| * system workqueue and blocks until all CPUs have completed. |
| * schedule_on_each_cpu() is very slow. |
| * |
| * RETURNS: |
| * 0 on success, -errno on failure. |
| */ |
| int schedule_on_each_cpu(work_func_t func) |
| { |
| int cpu; |
| struct work_struct __percpu *works; |
| |
| works = alloc_percpu(struct work_struct); |
| if (!works) |
| return -ENOMEM; |
| |
| get_online_cpus(); |
| |
| for_each_online_cpu(cpu) { |
| struct work_struct *work = per_cpu_ptr(works, cpu); |
| |
| INIT_WORK(work, func); |
| schedule_work_on(cpu, work); |
| } |
| |
| for_each_online_cpu(cpu) |
| flush_work(per_cpu_ptr(works, cpu)); |
| |
| put_online_cpus(); |
| free_percpu(works); |
| return 0; |
| } |
| |
| /** |
| * flush_scheduled_work - ensure that any scheduled work has run to completion. |
| * |
| * Forces execution of the kernel-global workqueue and blocks until its |
| * completion. |
| * |
| * Think twice before calling this function! It's very easy to get into |
| * trouble if you don't take great care. Either of the following situations |
| * will lead to deadlock: |
| * |
| * One of the work items currently on the workqueue needs to acquire |
| * a lock held by your code or its caller. |
| * |
| * Your code is running in the context of a work routine. |
| * |
| * They will be detected by lockdep when they occur, but the first might not |
| * occur very often. It depends on what work items are on the workqueue and |
| * what locks they need, which you have no control over. |
| * |
| * In most situations flushing the entire workqueue is overkill; you merely |
| * need to know that a particular work item isn't queued and isn't running. |
| * In such cases you should use cancel_delayed_work_sync() or |
| * cancel_work_sync() instead. |
| */ |
| void flush_scheduled_work(void) |
| { |
| flush_workqueue(system_wq); |
| } |
| EXPORT_SYMBOL(flush_scheduled_work); |
| |
| /** |
| * execute_in_process_context - reliably execute the routine with user context |
| * @fn: the function to execute |
| * @ew: guaranteed storage for the execute work structure (must |
| * be available when the work executes) |
| * |
| * Executes the function immediately if process context is available, |
| * otherwise schedules the function for delayed execution. |
| * |
| * Returns: 0 - function was executed |
| * 1 - function was scheduled for execution |
| */ |
| int execute_in_process_context(work_func_t fn, struct execute_work *ew) |
| { |
| if (!in_interrupt()) { |
| fn(&ew->work); |
| return 0; |
| } |
| |
| INIT_WORK(&ew->work, fn); |
| schedule_work(&ew->work); |
| |
| return 1; |
| } |
| EXPORT_SYMBOL_GPL(execute_in_process_context); |
| |
| int keventd_up(void) |
| { |
| return system_wq != NULL; |
| } |
| |
| static int alloc_cwqs(struct workqueue_struct *wq) |
| { |
| /* |
| * cwqs are forced aligned according to WORK_STRUCT_FLAG_BITS. |
| * Make sure that the alignment isn't lower than that of |
| * unsigned long long. |
| */ |
| const size_t size = sizeof(struct cpu_workqueue_struct); |
| const size_t align = max_t(size_t, 1 << WORK_STRUCT_FLAG_BITS, |
| __alignof__(unsigned long long)); |
| #ifdef CONFIG_SMP |
| bool percpu = !(wq->flags & WQ_UNBOUND); |
| #else |
| bool percpu = false; |
| #endif |
| |
| if (percpu) |
| wq->cpu_wq.pcpu = __alloc_percpu(size, align); |
| else { |
| void *ptr; |
| |
| /* |
| * Allocate enough room to align cwq and put an extra |
| * pointer at the end pointing back to the originally |
| * allocated pointer which will be used for free. |
| */ |
| ptr = kzalloc(size + align + sizeof(void *), GFP_KERNEL); |
| if (ptr) { |
| wq->cpu_wq.single = PTR_ALIGN(ptr, align); |
| *(void **)(wq->cpu_wq.single + 1) = ptr; |
| } |
| } |
| |
| /* just in case, make sure it's actually aligned |
| * - this is affected by PERCPU() alignment in vmlinux.lds.S |
| */ |
| BUG_ON(!IS_ALIGNED(wq->cpu_wq.v, align)); |
| return wq->cpu_wq.v ? 0 : -ENOMEM; |
| } |
| |
| static void free_cwqs(struct workqueue_struct *wq) |
| { |
| #ifdef CONFIG_SMP |
| bool percpu = !(wq->flags & WQ_UNBOUND); |
| #else |
| bool percpu = false; |
| #endif |
| |
| if (percpu) |
| free_percpu(wq->cpu_wq.pcpu); |
| else if (wq->cpu_wq.single) { |
| /* the pointer to free is stored right after the cwq */ |
| kfree(*(void **)(wq->cpu_wq.single + 1)); |
| } |
| } |
| |
| static int wq_clamp_max_active(int max_active, unsigned int flags, |
| const char *name) |
| { |
| int lim = flags & WQ_UNBOUND ? WQ_UNBOUND_MAX_ACTIVE : WQ_MAX_ACTIVE; |
| |
| if (max_active < 1 || max_active > lim) |
| printk(KERN_WARNING "workqueue: max_active %d requested for %s " |
| "is out of range, clamping between %d and %d\n", |
| max_active, name, 1, lim); |
| |
| return clamp_val(max_active, 1, lim); |
| } |
| |
| struct workqueue_struct *__alloc_workqueue_key(const char *name, |
| unsigned int flags, |
| int max_active, |
| struct lock_class_key *key, |
| const char *lock_name) |
| { |
| struct workqueue_struct *wq; |
| unsigned int cpu; |
| |
| /* |
| * Workqueues which may be used during memory reclaim should |
| * have a rescuer to guarantee forward progress. |
| */ |
| if (flags & WQ_MEM_RECLAIM) |
| flags |= WQ_RESCUER; |
| |
| /* |
| * Unbound workqueues aren't concurrency managed and should be |
| * dispatched to workers immediately. |
| */ |
| if (flags & WQ_UNBOUND) |
| flags |= WQ_HIGHPRI; |
| |
| max_active = max_active ?: WQ_DFL_ACTIVE; |
| max_active = wq_clamp_max_active(max_active, flags, name); |
| |
| wq = kzalloc(sizeof(*wq), GFP_KERNEL); |
| if (!wq) |
| goto err; |
| |
| wq->flags = flags; |
| wq->saved_max_active = max_active; |
| mutex_init(&wq->flush_mutex); |
| atomic_set(&wq->nr_cwqs_to_flush, 0); |
| INIT_LIST_HEAD(&wq->flusher_queue); |
| INIT_LIST_HEAD(&wq->flusher_overflow); |
| |
| wq->name = name; |
| lockdep_init_map(&wq->lockdep_map, lock_name, key, 0); |
| INIT_LIST_HEAD(&wq->list); |
| |
| if (alloc_cwqs(wq) < 0) |
| goto err; |
| |
| for_each_cwq_cpu(cpu, wq) { |
| struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); |
| struct global_cwq *gcwq = get_gcwq(cpu); |
| |
| BUG_ON((unsigned long)cwq & WORK_STRUCT_FLAG_MASK); |
| cwq->gcwq = gcwq; |
| cwq->wq = wq; |
| cwq->flush_color = -1; |
| cwq->max_active = max_active; |
| INIT_LIST_HEAD(&cwq->delayed_works); |
| } |
| |
| if (flags & WQ_RESCUER) { |
| struct worker *rescuer; |
| |
| if (!alloc_mayday_mask(&wq->mayday_mask, GFP_KERNEL)) |
| goto err; |
| |
| wq->rescuer = rescuer = alloc_worker(); |
| if (!rescuer) |
| goto err; |
| |
| rescuer->task = kthread_create(rescuer_thread, wq, "%s", name); |
| if (IS_ERR(rescuer->task)) |
| goto err; |
| |
| rescuer->task->flags |= PF_THREAD_BOUND; |
| wake_up_process(rescuer->task); |
| } |
| |
| /* |
| * workqueue_lock protects global freeze state and workqueues |
| * list. Grab it, set max_active accordingly and add the new |
| * workqueue to workqueues list. |
| */ |
| spin_lock(&workqueue_lock); |
| |
| if (workqueue_freezing && wq->flags & WQ_FREEZEABLE) |
| for_each_cwq_cpu(cpu, wq) |
| get_cwq(cpu, wq)->max_active = 0; |
| |
| list_add(&wq->list, &workqueues); |
| |
| spin_unlock(&workqueue_lock); |
| |
| return wq; |
| err: |
| if (wq) { |
| free_cwqs(wq); |
| free_mayday_mask(wq->mayday_mask); |
| kfree(wq->rescuer); |
| kfree(wq); |
| } |
| return NULL; |
| } |
| EXPORT_SYMBOL_GPL(__alloc_workqueue_key); |
| |
| /** |
| * destroy_workqueue - safely terminate a workqueue |
| * @wq: target workqueue |
| * |
| * Safely destroy a workqueue. All work currently pending will be done first. |
| */ |
| void destroy_workqueue(struct workqueue_struct *wq) |
| { |
| unsigned int flush_cnt = 0; |
| unsigned int cpu; |
| |
| /* |
| * Mark @wq dying and drain all pending works. Once WQ_DYING is |
| * set, only chain queueing is allowed. IOW, only currently |
| * pending or running work items on @wq can queue further work |
| * items on it. @wq is flushed repeatedly until it becomes empty. |
| * The number of flushing is detemined by the depth of chaining and |
| * should be relatively short. Whine if it takes too long. |
| */ |
| wq->flags |= WQ_DYING; |
| reflush: |
| flush_workqueue(wq); |
| |
| for_each_cwq_cpu(cpu, wq) { |
| struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); |
| |
| if (!cwq->nr_active && list_empty(&cwq->delayed_works)) |
| continue; |
| |
| if (++flush_cnt == 10 || |
| (flush_cnt % 100 == 0 && flush_cnt <= 1000)) |
| printk(KERN_WARNING "workqueue %s: flush on " |
| "destruction isn't complete after %u tries\n", |
| wq->name, flush_cnt); |
| goto reflush; |
| } |
| |
| /* |
| * wq list is used to freeze wq, remove from list after |
| * flushing is complete in case freeze races us. |
| */ |
| spin_lock(&workqueue_lock); |
| list_del(&wq->list); |
| spin_unlock(&workqueue_lock); |
| |
| /* sanity check */ |
| for_each_cwq_cpu(cpu, wq) { |
| struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); |
| int i; |
| |
| for (i = 0; i < WORK_NR_COLORS; i++) |
| BUG_ON(cwq->nr_in_flight[i]); |
| BUG_ON(cwq->nr_active); |
| BUG_ON(!list_empty(&cwq->delayed_works)); |
| } |
| |
| if (wq->flags & WQ_RESCUER) { |
| kthread_stop(wq->rescuer->task); |
| free_mayday_mask(wq->mayday_mask); |
| kfree(wq->rescuer); |
| } |
| |
| free_cwqs(wq); |
| kfree(wq); |
| } |
| EXPORT_SYMBOL_GPL(destroy_workqueue); |
| |
| /** |
| * workqueue_set_max_active - adjust max_active of a workqueue |
| * @wq: target workqueue |
| * @max_active: new max_active value. |
| * |
| * Set max_active of @wq to @max_active. |
| * |
| * CONTEXT: |
| * Don't call from IRQ context. |
| */ |
| void workqueue_set_max_active(struct workqueue_struct *wq, int max_active) |
| { |
| unsigned int cpu; |
| |
| max_active = wq_clamp_max_active(max_active, wq->flags, wq->name); |
| |
| spin_lock(&workqueue_lock); |
| |
| wq->saved_max_active = max_active; |
| |
| for_each_cwq_cpu(cpu, wq) { |
| struct global_cwq *gcwq = get_gcwq(cpu); |
| |
| spin_lock_irq(&gcwq->lock); |
| |
| if (!(wq->flags & WQ_FREEZEABLE) || |
| !(gcwq->flags & GCWQ_FREEZING)) |
| get_cwq(gcwq->cpu, wq)->max_active = max_active; |
| |
| spin_unlock_irq(&gcwq->lock); |
| } |
| |
| spin_unlock(&workqueue_lock); |
| } |
| EXPORT_SYMBOL_GPL(workqueue_set_max_active); |
| |
| /** |
| * workqueue_congested - test whether a workqueue is congested |
| * @cpu: CPU in question |
| * @wq: target workqueue |
| * |
| * Test whether @wq's cpu workqueue for @cpu is congested. There is |
| * no synchronization around this function and the test result is |
| * unreliable and only useful as advisory hints or for debugging. |
| * |
| * RETURNS: |
| * %true if congested, %false otherwise. |
| */ |
| bool workqueue_congested(unsigned int cpu, struct workqueue_struct *wq) |
| { |
| struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); |
| |
| return !list_empty(&cwq->delayed_works); |
| } |
| EXPORT_SYMBOL_GPL(workqueue_congested); |
| |
| /** |
| * work_cpu - return the last known associated cpu for @work |
| * @work: the work of interest |
| * |
| * RETURNS: |
| * CPU number if @work was ever queued. WORK_CPU_NONE otherwise. |
| */ |
| unsigned int work_cpu(struct work_struct *work) |
| { |
| struct global_cwq *gcwq = get_work_gcwq(work); |
| |
| return gcwq ? gcwq->cpu : WORK_CPU_NONE; |
| } |
| EXPORT_SYMBOL_GPL(work_cpu); |
| |
| /** |
| * work_busy - test whether a work is currently pending or running |
| * @work: the work to be tested |
| * |
| * Test whether @work is currently pending or running. There is no |
| * synchronization around this function and the test result is |
| * unreliable and only useful as advisory hints or for debugging. |
| * Especially for reentrant wqs, the pending state might hide the |
| * running state. |
| * |
| * RETURNS: |
| * OR'd bitmask of WORK_BUSY_* bits. |
| */ |
| unsigned int work_busy(struct work_struct *work) |
| { |
| struct global_cwq *gcwq = get_work_gcwq(work); |
| unsigned long flags; |
| unsigned int ret = 0; |
| |
| if (!gcwq) |
| return false; |
| |
| spin_lock_irqsave(&gcwq->lock, flags); |
| |
| if (work_pending(work)) |
| ret |= WORK_BUSY_PENDING; |
| if (find_worker_executing_work(gcwq, work)) |
| ret |= WORK_BUSY_RUNNING; |
| |
| spin_unlock_irqrestore(&gcwq->lock, flags); |
| |
| return ret; |
| } |
| EXPORT_SYMBOL_GPL(work_busy); |
| |
| /* |
| * CPU hotplug. |
| * |
| * There are two challenges in supporting CPU hotplug. Firstly, there |
| * are a lot of assumptions on strong associations among work, cwq and |
| * gcwq which make migrating pending and scheduled works very |
| * difficult to implement without impacting hot paths. Secondly, |
| * gcwqs serve mix of short, long and very long running works making |
| * blocked draining impractical. |
| * |
| * This is solved by allowing a gcwq to be detached from CPU, running |
| * it with unbound (rogue) workers and allowing it to be reattached |
| * later if the cpu comes back online. A separate thread is created |
| * to govern a gcwq in such state and is called the trustee of the |
| * gcwq. |
| * |
| * Trustee states and their descriptions. |
| * |
| * START Command state used on startup. On CPU_DOWN_PREPARE, a |
| * new trustee is started with this state. |
| * |
| * IN_CHARGE Once started, trustee will enter this state after |
| * assuming the manager role and making all existing |
| * workers rogue. DOWN_PREPARE waits for trustee to |
| * enter this state. After reaching IN_CHARGE, trustee |
| * tries to execute the pending worklist until it's empty |
| * and the state is set to BUTCHER, or the state is set |
| * to RELEASE. |
| * |
| * BUTCHER Command state which is set by the cpu callback after |
| * the cpu has went down. Once this state is set trustee |
| * knows that there will be no new works on the worklist |
| * and once the worklist is empty it can proceed to |
| * killing idle workers. |
| * |
| * RELEASE Command state which is set by the cpu callback if the |
| * cpu down has been canceled or it has come online |
| * again. After recognizing this state, trustee stops |
| * trying to drain or butcher and clears ROGUE, rebinds |
| * all remaining workers back to the cpu and releases |
| * manager role. |
| * |
| * DONE Trustee will enter this state after BUTCHER or RELEASE |
| * is complete. |
| * |
| * trustee CPU draining |
| * took over down complete |
| * START -----------> IN_CHARGE -----------> BUTCHER -----------> DONE |
| * | | ^ |
| * | CPU is back online v return workers | |
| * ----------------> RELEASE -------------- |
| */ |
| |
| /** |
| * trustee_wait_event_timeout - timed event wait for trustee |
| * @cond: condition to wait for |
| * @timeout: timeout in jiffies |
| * |
| * wait_event_timeout() for trustee to use. Handles locking and |
| * checks for RELEASE request. |
| * |
| * CONTEXT: |
| * spin_lock_irq(gcwq->lock) which may be released and regrabbed |
| * multiple times. To be used by trustee. |
| * |
| * RETURNS: |
| * Positive indicating left time if @cond is satisfied, 0 if timed |
| * out, -1 if canceled. |
| */ |
| #define trustee_wait_event_timeout(cond, timeout) ({ \ |
| long __ret = (timeout); \ |
| while (!((cond) || (gcwq->trustee_state == TRUSTEE_RELEASE)) && \ |
| __ret) { \ |
| spin_unlock_irq(&gcwq->lock); \ |
| __wait_event_timeout(gcwq->trustee_wait, (cond) || \ |
| (gcwq->trustee_state == TRUSTEE_RELEASE), \ |
| __ret); \ |
| spin_lock_irq(&gcwq->lock); \ |
| } \ |
| gcwq->trustee_state == TRUSTEE_RELEASE ? -1 : (__ret); \ |
| }) |
| |
| /** |
| * trustee_wait_event - event wait for trustee |
| * @cond: condition to wait for |
| * |
| * wait_event() for trustee to use. Automatically handles locking and |
| * checks for CANCEL request. |
| * |
| * CONTEXT: |
| * spin_lock_irq(gcwq->lock) which may be released and regrabbed |
| * multiple times. To be used by trustee. |
| * |
| * RETURNS: |
| * 0 if @cond is satisfied, -1 if canceled. |
| */ |
| #define trustee_wait_event(cond) ({ \ |
| long __ret1; \ |
| __ret1 = trustee_wait_event_timeout(cond, MAX_SCHEDULE_TIMEOUT);\ |
| __ret1 < 0 ? -1 : 0; \ |
| }) |
| |
| static int __cpuinit trustee_thread(void *__gcwq) |
| { |
| struct global_cwq *gcwq = __gcwq; |
| struct worker *worker; |
| struct work_struct *work; |
| struct hlist_node *pos; |
| long rc; |
| int i; |
| |
| BUG_ON(gcwq->cpu != smp_processor_id()); |
| |
| spin_lock_irq(&gcwq->lock); |
| /* |
| * Claim the manager position and make all workers rogue. |
| * Trustee must be bound to the target cpu and can't be |
| * cancelled. |
| */ |
| BUG_ON(gcwq->cpu != smp_processor_id()); |
| rc = trustee_wait_event(!(gcwq->flags & GCWQ_MANAGING_WORKERS)); |
| BUG_ON(rc < 0); |
| |
| gcwq->flags |= GCWQ_MANAGING_WORKERS; |
| |
| list_for_each_entry(worker, &gcwq->idle_list, entry) |
| worker->flags |= WORKER_ROGUE; |
| |
| for_each_busy_worker(worker, i, pos, gcwq) |
| worker->flags |= WORKER_ROGUE; |
| |
| /* |
| * Call schedule() so that we cross rq->lock and thus can |
| * guarantee sched callbacks see the rogue flag. This is |
| * necessary as scheduler callbacks may be invoked from other |
| * cpus. |
| */ |
| spin_unlock_irq(&gcwq->lock); |
| schedule(); |
| spin_lock_irq(&gcwq->lock); |
| |
| /* |
| * Sched callbacks are disabled now. Zap nr_running. After |
| * this, nr_running stays zero and need_more_worker() and |
| * keep_working() are always true as long as the worklist is |
| * not empty. |
| */ |
| atomic_set(get_gcwq_nr_running(gcwq->cpu), 0); |
| |
| spin_unlock_irq(&gcwq->lock); |
| del_timer_sync(&gcwq->idle_timer); |
| spin_lock_irq(&gcwq->lock); |
| |
| /* |
| * We're now in charge. Notify and proceed to drain. We need |
| * to keep the gcwq running during the whole CPU down |
| * procedure as other cpu hotunplug callbacks may need to |
| * flush currently running tasks. |
| */ |
| gcwq->trustee_state = TRUSTEE_IN_CHARGE; |
| wake_up_all(&gcwq->trustee_wait); |
| |
| /* |
| * The original cpu is in the process of dying and may go away |
| * anytime now. When that happens, we and all workers would |
| * be migrated to other cpus. Try draining any left work. We |
| * want to get it over with ASAP - spam rescuers, wake up as |
| * many idlers as necessary and create new ones till the |
| * worklist is empty. Note that if the gcwq is frozen, there |
| * may be frozen works in freezeable cwqs. Don't declare |
| * completion while frozen. |
| */ |
| while (gcwq->nr_workers != gcwq->nr_idle || |
| gcwq->flags & GCWQ_FREEZING || |
| gcwq->trustee_state == TRUSTEE_IN_CHARGE) { |
| int nr_works = 0; |
| |
| list_for_each_entry(work, &gcwq->worklist, entry) { |
| send_mayday(work); |
| nr_works++; |
| } |
| |
| list_for_each_entry(worker, &gcwq->idle_list, entry) { |
| if (!nr_works--) |
| break; |
| wake_up_process(worker->task); |
| } |
| |
| if (need_to_create_worker(gcwq)) { |
| spin_unlock_irq(&gcwq->lock); |
| worker = create_worker(gcwq, false); |
| spin_lock_irq(&gcwq->lock); |
| if (worker) { |
| worker->flags |= WORKER_ROGUE; |
| start_worker(worker); |
| } |
| } |
| |
| /* give a breather */ |
| if (trustee_wait_event_timeout(false, TRUSTEE_COOLDOWN) < 0) |
| break; |
| } |
| |
| /* |
| * Either all works have been scheduled and cpu is down, or |
| * cpu down has already been canceled. Wait for and butcher |
| * all workers till we're canceled. |
| */ |
| do { |
| rc = trustee_wait_event(!list_empty(&gcwq->idle_list)); |
| while (!list_empty(&gcwq->idle_list)) |
| destroy_worker(list_first_entry(&gcwq->idle_list, |
| struct worker, entry)); |
| } while (gcwq->nr_workers && rc >= 0); |
| |
| /* |
| * At this point, either draining has completed and no worker |
| * is left, or cpu down has been canceled or the cpu is being |
| * brought back up. There shouldn't be any idle one left. |
| * Tell the remaining busy ones to rebind once it finishes the |
| * currently scheduled works by scheduling the rebind_work. |
| */ |
| WARN_ON(!list_empty(&gcwq->idle_list)); |
| |
| for_each_busy_worker(worker, i, pos, gcwq) { |
| struct work_struct *rebind_work = &worker->rebind_work; |
| |
| /* |
| * Rebind_work may race with future cpu hotplug |
| * operations. Use a separate flag to mark that |
| * rebinding is scheduled. |
| */ |
| worker->flags |= WORKER_REBIND; |
| worker->flags &= ~WORKER_ROGUE; |
| |
| /* queue rebind_work, wq doesn't matter, use the default one */ |
| if (test_and_set_bit(WORK_STRUCT_PENDING_BIT, |
| work_data_bits(rebind_work))) |
| continue; |
| |
| debug_work_activate(rebind_work); |
| insert_work(get_cwq(gcwq->cpu, system_wq), rebind_work, |
| worker->scheduled.next, |
| work_color_to_flags(WORK_NO_COLOR)); |
| } |
| |
| /* relinquish manager role */ |
| gcwq->flags &= ~GCWQ_MANAGING_WORKERS; |
| |
| /* notify completion */ |
| gcwq->trustee = NULL; |
| gcwq->trustee_state = TRUSTEE_DONE; |
| wake_up_all(&gcwq->trustee_wait); |
| spin_unlock_irq(&gcwq->lock); |
| return 0; |
| } |
| |
| /** |
| * wait_trustee_state - wait for trustee to enter the specified state |
| * @gcwq: gcwq the trustee of interest belongs to |
| * @state: target state to wait for |
| * |
| * Wait for the trustee to reach @state. DONE is already matched. |
| * |
| * CONTEXT: |
| * spin_lock_irq(gcwq->lock) which may be released and regrabbed |
| * multiple times. To be used by cpu_callback. |
| */ |
| static void __cpuinit wait_trustee_state(struct global_cwq *gcwq, int state) |
| __releases(&gcwq->lock) |
| __acquires(&gcwq->lock) |
| { |
| if (!(gcwq->trustee_state == state || |
| gcwq->trustee_state == TRUSTEE_DONE)) { |
| spin_unlock_irq(&gcwq->lock); |
| __wait_event(gcwq->trustee_wait, |
| gcwq->trustee_state == state || |
| gcwq->trustee_state == TRUSTEE_DONE); |
| spin_lock_irq(&gcwq->lock); |
| } |
| } |
| |
| static int __devinit workqueue_cpu_callback(struct notifier_block *nfb, |
| unsigned long action, |
| void *hcpu) |
| { |
| unsigned int cpu = (unsigned long)hcpu; |
| struct global_cwq *gcwq = get_gcwq(cpu); |
| struct task_struct *new_trustee = NULL; |
| struct worker *uninitialized_var(new_worker); |
| unsigned long flags; |
| |
| action &= ~CPU_TASKS_FROZEN; |
| |
| switch (action) { |
| case CPU_DOWN_PREPARE: |
| new_trustee = kthread_create(trustee_thread, gcwq, |
| "workqueue_trustee/%d\n", cpu); |
| if (IS_ERR(new_trustee)) |
| return notifier_from_errno(PTR_ERR(new_trustee)); |
| kthread_bind(new_trustee, cpu); |
| /* fall through */ |
| case CPU_UP_PREPARE: |
| BUG_ON(gcwq->first_idle); |
| new_worker = create_worker(gcwq, false); |
| if (!new_worker) { |
| if (new_trustee) |
| kthread_stop(new_trustee); |
| return NOTIFY_BAD; |
| } |
| } |
| |
| /* some are called w/ irq disabled, don't disturb irq status */ |
| spin_lock_irqsave(&gcwq->lock, flags); |
| |
| switch (action) { |
| case CPU_DOWN_PREPARE: |
| /* initialize trustee and tell it to acquire the gcwq */ |
| BUG_ON(gcwq->trustee || gcwq->trustee_state != TRUSTEE_DONE); |
| gcwq->trustee = new_trustee; |
| gcwq->trustee_state = TRUSTEE_START; |
| wake_up_process(gcwq->trustee); |
| wait_trustee_state(gcwq, TRUSTEE_IN_CHARGE); |
| /* fall through */ |
| case CPU_UP_PREPARE: |
| BUG_ON(gcwq->first_idle); |
| gcwq->first_idle = new_worker; |
| break; |
| |
| case CPU_DYING: |
| /* |
| * Before this, the trustee and all workers except for |
| * the ones which are still executing works from |
| * before the last CPU down must be on the cpu. After |
| * this, they'll all be diasporas. |
| */ |
| gcwq->flags |= GCWQ_DISASSOCIATED; |
| break; |
| |
| case CPU_POST_DEAD: |
| gcwq->trustee_state = TRUSTEE_BUTCHER; |
| /* fall through */ |
| case CPU_UP_CANCELED: |
| destroy_worker(gcwq->first_idle); |
| gcwq->first_idle = NULL; |
| break; |
| |
| case CPU_DOWN_FAILED: |
| case CPU_ONLINE: |
| gcwq->flags &= ~GCWQ_DISASSOCIATED; |
| if (gcwq->trustee_state != TRUSTEE_DONE) { |
| gcwq->trustee_state = TRUSTEE_RELEASE; |
| wake_up_process(gcwq->trustee); |
| wait_trustee_state(gcwq, TRUSTEE_DONE); |
| } |
| |
| /* |
| * Trustee is done and there might be no worker left. |
| * Put the first_idle in and request a real manager to |
| * take a look. |
| */ |
| spin_unlock_irq(&gcwq->lock); |
| kthread_bind(gcwq->first_idle->task, cpu); |
| spin_lock_irq(&gcwq->lock); |
| gcwq->flags |= GCWQ_MANAGE_WORKERS; |
| start_worker(gcwq->first_idle); |
| gcwq->first_idle = NULL; |
| break; |
| } |
| |
| spin_unlock_irqrestore(&gcwq->lock, flags); |
| |
| return notifier_from_errno(0); |
| } |
| |
| #ifdef CONFIG_SMP |
| |
| struct work_for_cpu { |
| struct completion completion; |
| long (*fn)(void *); |
| void *arg; |
| long ret; |
| }; |
| |
| static int do_work_for_cpu(void *_wfc) |
| { |
| struct work_for_cpu *wfc = _wfc; |
| wfc->ret = wfc->fn(wfc->arg); |
| complete(&wfc->completion); |
| return 0; |
| } |
| |
| /** |
| * work_on_cpu - run a function in user context on a particular cpu |
| * @cpu: the cpu to run on |
| * @fn: the function to run |
| * @arg: the function arg |
| * |
| * This will return the value @fn returns. |
| * It is up to the caller to ensure that the cpu doesn't go offline. |
| * The caller must not hold any locks which would prevent @fn from completing. |
| */ |
| long work_on_cpu(unsigned int cpu, long (*fn)(void *), void *arg) |
| { |
| struct task_struct *sub_thread; |
| struct work_for_cpu wfc = { |
| .completion = COMPLETION_INITIALIZER_ONSTACK(wfc.completion), |
| .fn = fn, |
| .arg = arg, |
| }; |
| |
| sub_thread = kthread_create(do_work_for_cpu, &wfc, "work_for_cpu"); |
| if (IS_ERR(sub_thread)) |
| return PTR_ERR(sub_thread); |
| kthread_bind(sub_thread, cpu); |
| wake_up_process(sub_thread); |
| wait_for_completion(&wfc.completion); |
| return wfc.ret; |
| } |
| EXPORT_SYMBOL_GPL(work_on_cpu); |
| #endif /* CONFIG_SMP */ |
| |
| #ifdef CONFIG_FREEZER |
| |
| /** |
| * freeze_workqueues_begin - begin freezing workqueues |
| * |
| * Start freezing workqueues. After this function returns, all |
| * freezeable workqueues will queue new works to their frozen_works |
| * list instead of gcwq->worklist. |
| * |
| * CONTEXT: |
| * Grabs and releases workqueue_lock and gcwq->lock's. |
| */ |
| void freeze_workqueues_begin(void) |
| { |
| unsigned int cpu; |
| |
| spin_lock(&workqueue_lock); |
| |
| BUG_ON(workqueue_freezing); |
| workqueue_freezing = true; |
| |
| for_each_gcwq_cpu(cpu) { |
| struct global_cwq *gcwq = get_gcwq(cpu); |
| struct workqueue_struct *wq; |
| |
| spin_lock_irq(&gcwq->lock); |
| |
| BUG_ON(gcwq->flags & GCWQ_FREEZING); |
| gcwq->flags |= GCWQ_FREEZING; |
| |
| list_for_each_entry(wq, &workqueues, list) { |
| struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); |
| |
| if (cwq && wq->flags & WQ_FREEZEABLE) |
| cwq->max_active = 0; |
| } |
| |
| spin_unlock_irq(&gcwq->lock); |
| } |
| |
| spin_unlock(&workqueue_lock); |
| } |
| |
| /** |
| * freeze_workqueues_busy - are freezeable workqueues still busy? |
| * |
| * Check whether freezing is complete. This function must be called |
| * between freeze_workqueues_begin() and thaw_workqueues(). |
| * |
| * CONTEXT: |
| * Grabs and releases workqueue_lock. |
| * |
| * RETURNS: |
| * %true if some freezeable workqueues are still busy. %false if |
| * freezing is complete. |
| */ |
| bool freeze_workqueues_busy(void) |
| { |
| unsigned int cpu; |
| bool busy = false; |
| |
| spin_lock(&workqueue_lock); |
| |
| BUG_ON(!workqueue_freezing); |
| |
| for_each_gcwq_cpu(cpu) { |
| struct workqueue_struct *wq; |
| /* |
| * nr_active is monotonically decreasing. It's safe |
| * to peek without lock. |
| */ |
| list_for_each_entry(wq, &workqueues, list) { |
| struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); |
| |
| if (!cwq || !(wq->flags & WQ_FREEZEABLE)) |
| continue; |
| |
| BUG_ON(cwq->nr_active < 0); |
| if (cwq->nr_active) { |
| busy = true; |
| goto out_unlock; |
| } |
| } |
| } |
| out_unlock: |
| spin_unlock(&workqueue_lock); |
| return busy; |
| } |
| |
| /** |
| * thaw_workqueues - thaw workqueues |
| * |
| * Thaw workqueues. Normal queueing is restored and all collected |
| * frozen works are transferred to their respective gcwq worklists. |
| * |
| * CONTEXT: |
| * Grabs and releases workqueue_lock and gcwq->lock's. |
| */ |
| void thaw_workqueues(void) |
| { |
| unsigned int cpu; |
| |
| spin_lock(&workqueue_lock); |
| |
| if (!workqueue_freezing) |
| goto out_unlock; |
| |
| for_each_gcwq_cpu(cpu) { |
| struct global_cwq *gcwq = get_gcwq(cpu); |
| struct workqueue_struct *wq; |
| |
| spin_lock_irq(&gcwq->lock); |
| |
| BUG_ON(!(gcwq->flags & GCWQ_FREEZING)); |
| gcwq->flags &= ~GCWQ_FREEZING; |
| |
| list_for_each_entry(wq, &workqueues, list) { |
| struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); |
| |
| if (!cwq || !(wq->flags & WQ_FREEZEABLE)) |
| continue; |
| |
| /* restore max_active and repopulate worklist */ |
| cwq->max_active = wq->saved_max_active; |
| |
| while (!list_empty(&cwq->delayed_works) && |
| cwq->nr_active < cwq->max_active) |
| cwq_activate_first_delayed(cwq); |
| } |
| |
| wake_up_worker(gcwq); |
| |
| spin_unlock_irq(&gcwq->lock); |
| } |
| |
| workqueue_freezing = false; |
| out_unlock: |
| spin_unlock(&workqueue_lock); |
| } |
| #endif /* CONFIG_FREEZER */ |
| |
| static int __init init_workqueues(void) |
| { |
| unsigned int cpu; |
| int i; |
| |
| cpu_notifier(workqueue_cpu_callback, CPU_PRI_WORKQUEUE); |
| |
| /* initialize gcwqs */ |
| for_each_gcwq_cpu(cpu) { |
| struct global_cwq *gcwq = get_gcwq(cpu); |
| |
| spin_lock_init(&gcwq->lock); |
| INIT_LIST_HEAD(&gcwq->worklist); |
| gcwq->cpu = cpu; |
| gcwq->flags |= GCWQ_DISASSOCIATED; |
| |
| INIT_LIST_HEAD(&gcwq->idle_list); |
| for (i = 0; i < BUSY_WORKER_HASH_SIZE; i++) |
| INIT_HLIST_HEAD(&gcwq->busy_hash[i]); |
| |
| init_timer_deferrable(&gcwq->idle_timer); |
| gcwq->idle_timer.function = idle_worker_timeout; |
| gcwq->idle_timer.data = (unsigned long)gcwq; |
| |
| setup_timer(&gcwq->mayday_timer, gcwq_mayday_timeout, |
| (unsigned long)gcwq); |
| |
| ida_init(&gcwq->worker_ida); |
| |
| gcwq->trustee_state = TRUSTEE_DONE; |
| init_waitqueue_head(&gcwq->trustee_wait); |
| } |
| |
| /* create the initial worker */ |
| for_each_online_gcwq_cpu(cpu) { |
| struct global_cwq *gcwq = get_gcwq(cpu); |
| struct worker *worker; |
| |
| if (cpu != WORK_CPU_UNBOUND) |
| gcwq->flags &= ~GCWQ_DISASSOCIATED; |
| worker = create_worker(gcwq, true); |
| BUG_ON(!worker); |
| spin_lock_irq(&gcwq->lock); |
| start_worker(worker); |
| spin_unlock_irq(&gcwq->lock); |
| } |
| |
| system_wq = alloc_workqueue("events", 0, 0); |
| system_long_wq = alloc_workqueue("events_long", 0, 0); |
| system_nrt_wq = alloc_workqueue("events_nrt", WQ_NON_REENTRANT, 0); |
| system_unbound_wq = alloc_workqueue("events_unbound", WQ_UNBOUND, |
| WQ_UNBOUND_MAX_ACTIVE); |
| BUG_ON(!system_wq || !system_long_wq || !system_nrt_wq || |
| !system_unbound_wq); |
| return 0; |
| } |
| early_initcall(init_workqueues); |