| /* SPDX-License-Identifier: GPL-2.0 */ |
| /* |
| * linux/cgroup-defs.h - basic definitions for cgroup |
| * |
| * This file provides basic type and interface. Include this file directly |
| * only if necessary to avoid cyclic dependencies. |
| */ |
| #ifndef _LINUX_CGROUP_DEFS_H |
| #define _LINUX_CGROUP_DEFS_H |
| |
| #include <linux/limits.h> |
| #include <linux/list.h> |
| #include <linux/idr.h> |
| #include <linux/wait.h> |
| #include <linux/mutex.h> |
| #include <linux/rcupdate.h> |
| #include <linux/refcount.h> |
| #include <linux/percpu-refcount.h> |
| #include <linux/percpu-rwsem.h> |
| #include <linux/workqueue.h> |
| #include <linux/bpf-cgroup.h> |
| |
| #ifdef CONFIG_CGROUPS |
| |
| struct cgroup; |
| struct cgroup_root; |
| struct cgroup_subsys; |
| struct cgroup_taskset; |
| struct kernfs_node; |
| struct kernfs_ops; |
| struct kernfs_open_file; |
| struct seq_file; |
| |
| #define MAX_CGROUP_TYPE_NAMELEN 32 |
| #define MAX_CGROUP_ROOT_NAMELEN 64 |
| #define MAX_CFTYPE_NAME 64 |
| |
| /* define the enumeration of all cgroup subsystems */ |
| #define SUBSYS(_x) _x ## _cgrp_id, |
| enum cgroup_subsys_id { |
| #include <linux/cgroup_subsys.h> |
| CGROUP_SUBSYS_COUNT, |
| }; |
| #undef SUBSYS |
| |
| /* bits in struct cgroup_subsys_state flags field */ |
| enum { |
| CSS_NO_REF = (1 << 0), /* no reference counting for this css */ |
| CSS_ONLINE = (1 << 1), /* between ->css_online() and ->css_offline() */ |
| CSS_RELEASED = (1 << 2), /* refcnt reached zero, released */ |
| CSS_VISIBLE = (1 << 3), /* css is visible to userland */ |
| CSS_DYING = (1 << 4), /* css is dying */ |
| }; |
| |
| /* bits in struct cgroup flags field */ |
| enum { |
| /* Control Group requires release notifications to userspace */ |
| CGRP_NOTIFY_ON_RELEASE, |
| /* |
| * Clone the parent's configuration when creating a new child |
| * cpuset cgroup. For historical reasons, this option can be |
| * specified at mount time and thus is implemented here. |
| */ |
| CGRP_CPUSET_CLONE_CHILDREN, |
| }; |
| |
| /* cgroup_root->flags */ |
| enum { |
| CGRP_ROOT_NOPREFIX = (1 << 1), /* mounted subsystems have no named prefix */ |
| CGRP_ROOT_XATTR = (1 << 2), /* supports extended attributes */ |
| |
| /* |
| * Consider namespaces as delegation boundaries. If this flag is |
| * set, controller specific interface files in a namespace root |
| * aren't writeable from inside the namespace. |
| */ |
| CGRP_ROOT_NS_DELEGATE = (1 << 3), |
| |
| /* |
| * Enable cpuset controller in v1 cgroup to use v2 behavior. |
| */ |
| CGRP_ROOT_CPUSET_V2_MODE = (1 << 4), |
| }; |
| |
| /* cftype->flags */ |
| enum { |
| CFTYPE_ONLY_ON_ROOT = (1 << 0), /* only create on root cgrp */ |
| CFTYPE_NOT_ON_ROOT = (1 << 1), /* don't create on root cgrp */ |
| CFTYPE_NS_DELEGATABLE = (1 << 2), /* writeable beyond delegation boundaries */ |
| |
| CFTYPE_NO_PREFIX = (1 << 3), /* (DON'T USE FOR NEW FILES) no subsys prefix */ |
| CFTYPE_WORLD_WRITABLE = (1 << 4), /* (DON'T USE FOR NEW FILES) S_IWUGO */ |
| |
| /* internal flags, do not use outside cgroup core proper */ |
| __CFTYPE_ONLY_ON_DFL = (1 << 16), /* only on default hierarchy */ |
| __CFTYPE_NOT_ON_DFL = (1 << 17), /* not on default hierarchy */ |
| }; |
| |
| /* |
| * cgroup_file is the handle for a file instance created in a cgroup which |
| * is used, for example, to generate file changed notifications. This can |
| * be obtained by setting cftype->file_offset. |
| */ |
| struct cgroup_file { |
| /* do not access any fields from outside cgroup core */ |
| struct kernfs_node *kn; |
| }; |
| |
| /* |
| * Per-subsystem/per-cgroup state maintained by the system. This is the |
| * fundamental structural building block that controllers deal with. |
| * |
| * Fields marked with "PI:" are public and immutable and may be accessed |
| * directly without synchronization. |
| */ |
| struct cgroup_subsys_state { |
| /* PI: the cgroup that this css is attached to */ |
| struct cgroup *cgroup; |
| |
| /* PI: the cgroup subsystem that this css is attached to */ |
| struct cgroup_subsys *ss; |
| |
| /* reference count - access via css_[try]get() and css_put() */ |
| struct percpu_ref refcnt; |
| |
| /* siblings list anchored at the parent's ->children */ |
| struct list_head sibling; |
| struct list_head children; |
| |
| /* |
| * PI: Subsys-unique ID. 0 is unused and root is always 1. The |
| * matching css can be looked up using css_from_id(). |
| */ |
| int id; |
| |
| unsigned int flags; |
| |
| /* |
| * Monotonically increasing unique serial number which defines a |
| * uniform order among all csses. It's guaranteed that all |
| * ->children lists are in the ascending order of ->serial_nr and |
| * used to allow interrupting and resuming iterations. |
| */ |
| u64 serial_nr; |
| |
| /* |
| * Incremented by online self and children. Used to guarantee that |
| * parents are not offlined before their children. |
| */ |
| atomic_t online_cnt; |
| |
| /* percpu_ref killing and RCU release */ |
| struct rcu_head rcu_head; |
| struct work_struct destroy_work; |
| |
| /* |
| * PI: the parent css. Placed here for cache proximity to following |
| * fields of the containing structure. |
| */ |
| struct cgroup_subsys_state *parent; |
| }; |
| |
| /* |
| * A css_set is a structure holding pointers to a set of |
| * cgroup_subsys_state objects. This saves space in the task struct |
| * object and speeds up fork()/exit(), since a single inc/dec and a |
| * list_add()/del() can bump the reference count on the entire cgroup |
| * set for a task. |
| */ |
| struct css_set { |
| /* |
| * Set of subsystem states, one for each subsystem. This array is |
| * immutable after creation apart from the init_css_set during |
| * subsystem registration (at boot time). |
| */ |
| struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT]; |
| |
| /* reference count */ |
| refcount_t refcount; |
| |
| /* |
| * For a domain cgroup, the following points to self. If threaded, |
| * to the matching cset of the nearest domain ancestor. The |
| * dom_cset provides access to the domain cgroup and its csses to |
| * which domain level resource consumptions should be charged. |
| */ |
| struct css_set *dom_cset; |
| |
| /* the default cgroup associated with this css_set */ |
| struct cgroup *dfl_cgrp; |
| |
| /* internal task count, protected by css_set_lock */ |
| int nr_tasks; |
| |
| /* |
| * Lists running through all tasks using this cgroup group. |
| * mg_tasks lists tasks which belong to this cset but are in the |
| * process of being migrated out or in. Protected by |
| * css_set_rwsem, but, during migration, once tasks are moved to |
| * mg_tasks, it can be read safely while holding cgroup_mutex. |
| */ |
| struct list_head tasks; |
| struct list_head mg_tasks; |
| |
| /* all css_task_iters currently walking this cset */ |
| struct list_head task_iters; |
| |
| /* |
| * On the default hierarhcy, ->subsys[ssid] may point to a css |
| * attached to an ancestor instead of the cgroup this css_set is |
| * associated with. The following node is anchored at |
| * ->subsys[ssid]->cgroup->e_csets[ssid] and provides a way to |
| * iterate through all css's attached to a given cgroup. |
| */ |
| struct list_head e_cset_node[CGROUP_SUBSYS_COUNT]; |
| |
| /* all threaded csets whose ->dom_cset points to this cset */ |
| struct list_head threaded_csets; |
| struct list_head threaded_csets_node; |
| |
| /* |
| * List running through all cgroup groups in the same hash |
| * slot. Protected by css_set_lock |
| */ |
| struct hlist_node hlist; |
| |
| /* |
| * List of cgrp_cset_links pointing at cgroups referenced from this |
| * css_set. Protected by css_set_lock. |
| */ |
| struct list_head cgrp_links; |
| |
| /* |
| * List of csets participating in the on-going migration either as |
| * source or destination. Protected by cgroup_mutex. |
| */ |
| struct list_head mg_preload_node; |
| struct list_head mg_node; |
| |
| /* |
| * If this cset is acting as the source of migration the following |
| * two fields are set. mg_src_cgrp and mg_dst_cgrp are |
| * respectively the source and destination cgroups of the on-going |
| * migration. mg_dst_cset is the destination cset the target tasks |
| * on this cset should be migrated to. Protected by cgroup_mutex. |
| */ |
| struct cgroup *mg_src_cgrp; |
| struct cgroup *mg_dst_cgrp; |
| struct css_set *mg_dst_cset; |
| |
| /* dead and being drained, ignore for migration */ |
| bool dead; |
| |
| /* For RCU-protected deletion */ |
| struct rcu_head rcu_head; |
| }; |
| |
| struct cgroup { |
| /* self css with NULL ->ss, points back to this cgroup */ |
| struct cgroup_subsys_state self; |
| |
| unsigned long flags; /* "unsigned long" so bitops work */ |
| |
| /* |
| * idr allocated in-hierarchy ID. |
| * |
| * ID 0 is not used, the ID of the root cgroup is always 1, and a |
| * new cgroup will be assigned with a smallest available ID. |
| * |
| * Allocating/Removing ID must be protected by cgroup_mutex. |
| */ |
| int id; |
| |
| /* |
| * The depth this cgroup is at. The root is at depth zero and each |
| * step down the hierarchy increments the level. This along with |
| * ancestor_ids[] can determine whether a given cgroup is a |
| * descendant of another without traversing the hierarchy. |
| */ |
| int level; |
| |
| /* Maximum allowed descent tree depth */ |
| int max_depth; |
| |
| /* |
| * Keep track of total numbers of visible and dying descent cgroups. |
| * Dying cgroups are cgroups which were deleted by a user, |
| * but are still existing because someone else is holding a reference. |
| * max_descendants is a maximum allowed number of descent cgroups. |
| */ |
| int nr_descendants; |
| int nr_dying_descendants; |
| int max_descendants; |
| |
| /* |
| * Each non-empty css_set associated with this cgroup contributes |
| * one to nr_populated_csets. The counter is zero iff this cgroup |
| * doesn't have any tasks. |
| * |
| * All children which have non-zero nr_populated_csets and/or |
| * nr_populated_children of their own contribute one to either |
| * nr_populated_domain_children or nr_populated_threaded_children |
| * depending on their type. Each counter is zero iff all cgroups |
| * of the type in the subtree proper don't have any tasks. |
| */ |
| int nr_populated_csets; |
| int nr_populated_domain_children; |
| int nr_populated_threaded_children; |
| |
| int nr_threaded_children; /* # of live threaded child cgroups */ |
| |
| struct kernfs_node *kn; /* cgroup kernfs entry */ |
| struct cgroup_file procs_file; /* handle for "cgroup.procs" */ |
| struct cgroup_file events_file; /* handle for "cgroup.events" */ |
| |
| /* |
| * The bitmask of subsystems enabled on the child cgroups. |
| * ->subtree_control is the one configured through |
| * "cgroup.subtree_control" while ->child_ss_mask is the effective |
| * one which may have more subsystems enabled. Controller knobs |
| * are made available iff it's enabled in ->subtree_control. |
| */ |
| u16 subtree_control; |
| u16 subtree_ss_mask; |
| u16 old_subtree_control; |
| u16 old_subtree_ss_mask; |
| |
| /* Private pointers for each registered subsystem */ |
| struct cgroup_subsys_state __rcu *subsys[CGROUP_SUBSYS_COUNT]; |
| |
| struct cgroup_root *root; |
| |
| /* |
| * List of cgrp_cset_links pointing at css_sets with tasks in this |
| * cgroup. Protected by css_set_lock. |
| */ |
| struct list_head cset_links; |
| |
| /* |
| * On the default hierarchy, a css_set for a cgroup with some |
| * susbsys disabled will point to css's which are associated with |
| * the closest ancestor which has the subsys enabled. The |
| * following lists all css_sets which point to this cgroup's css |
| * for the given subsystem. |
| */ |
| struct list_head e_csets[CGROUP_SUBSYS_COUNT]; |
| |
| /* |
| * If !threaded, self. If threaded, it points to the nearest |
| * domain ancestor. Inside a threaded subtree, cgroups are exempt |
| * from process granularity and no-internal-task constraint. |
| * Domain level resource consumptions which aren't tied to a |
| * specific task are charged to the dom_cgrp. |
| */ |
| struct cgroup *dom_cgrp; |
| struct cgroup *old_dom_cgrp; /* used while enabling threaded */ |
| |
| /* |
| * list of pidlists, up to two for each namespace (one for procs, one |
| * for tasks); created on demand. |
| */ |
| struct list_head pidlists; |
| struct mutex pidlist_mutex; |
| |
| /* used to wait for offlining of csses */ |
| wait_queue_head_t offline_waitq; |
| |
| /* used to schedule release agent */ |
| struct work_struct release_agent_work; |
| |
| /* used to store eBPF programs */ |
| struct cgroup_bpf bpf; |
| |
| /* ids of the ancestors at each level including self */ |
| int ancestor_ids[]; |
| }; |
| |
| /* |
| * A cgroup_root represents the root of a cgroup hierarchy, and may be |
| * associated with a kernfs_root to form an active hierarchy. This is |
| * internal to cgroup core. Don't access directly from controllers. |
| */ |
| struct cgroup_root { |
| struct kernfs_root *kf_root; |
| |
| /* The bitmask of subsystems attached to this hierarchy */ |
| unsigned int subsys_mask; |
| |
| /* Unique id for this hierarchy. */ |
| int hierarchy_id; |
| |
| /* The root cgroup. Root is destroyed on its release. */ |
| struct cgroup cgrp; |
| |
| /* for cgrp->ancestor_ids[0] */ |
| int cgrp_ancestor_id_storage; |
| |
| /* Number of cgroups in the hierarchy, used only for /proc/cgroups */ |
| atomic_t nr_cgrps; |
| |
| /* A list running through the active hierarchies */ |
| struct list_head root_list; |
| |
| /* Hierarchy-specific flags */ |
| unsigned int flags; |
| |
| /* IDs for cgroups in this hierarchy */ |
| struct idr cgroup_idr; |
| |
| /* The path to use for release notifications. */ |
| char release_agent_path[PATH_MAX]; |
| |
| /* The name for this hierarchy - may be empty */ |
| char name[MAX_CGROUP_ROOT_NAMELEN]; |
| }; |
| |
| /* |
| * struct cftype: handler definitions for cgroup control files |
| * |
| * When reading/writing to a file: |
| * - the cgroup to use is file->f_path.dentry->d_parent->d_fsdata |
| * - the 'cftype' of the file is file->f_path.dentry->d_fsdata |
| */ |
| struct cftype { |
| /* |
| * By convention, the name should begin with the name of the |
| * subsystem, followed by a period. Zero length string indicates |
| * end of cftype array. |
| */ |
| char name[MAX_CFTYPE_NAME]; |
| unsigned long private; |
| |
| /* |
| * The maximum length of string, excluding trailing nul, that can |
| * be passed to write. If < PAGE_SIZE-1, PAGE_SIZE-1 is assumed. |
| */ |
| size_t max_write_len; |
| |
| /* CFTYPE_* flags */ |
| unsigned int flags; |
| |
| /* |
| * If non-zero, should contain the offset from the start of css to |
| * a struct cgroup_file field. cgroup will record the handle of |
| * the created file into it. The recorded handle can be used as |
| * long as the containing css remains accessible. |
| */ |
| unsigned int file_offset; |
| |
| /* |
| * Fields used for internal bookkeeping. Initialized automatically |
| * during registration. |
| */ |
| struct cgroup_subsys *ss; /* NULL for cgroup core files */ |
| struct list_head node; /* anchored at ss->cfts */ |
| struct kernfs_ops *kf_ops; |
| |
| int (*open)(struct kernfs_open_file *of); |
| void (*release)(struct kernfs_open_file *of); |
| |
| /* |
| * read_u64() is a shortcut for the common case of returning a |
| * single integer. Use it in place of read() |
| */ |
| u64 (*read_u64)(struct cgroup_subsys_state *css, struct cftype *cft); |
| /* |
| * read_s64() is a signed version of read_u64() |
| */ |
| s64 (*read_s64)(struct cgroup_subsys_state *css, struct cftype *cft); |
| |
| /* generic seq_file read interface */ |
| int (*seq_show)(struct seq_file *sf, void *v); |
| |
| /* optional ops, implement all or none */ |
| void *(*seq_start)(struct seq_file *sf, loff_t *ppos); |
| void *(*seq_next)(struct seq_file *sf, void *v, loff_t *ppos); |
| void (*seq_stop)(struct seq_file *sf, void *v); |
| |
| /* |
| * write_u64() is a shortcut for the common case of accepting |
| * a single integer (as parsed by simple_strtoull) from |
| * userspace. Use in place of write(); return 0 or error. |
| */ |
| int (*write_u64)(struct cgroup_subsys_state *css, struct cftype *cft, |
| u64 val); |
| /* |
| * write_s64() is a signed version of write_u64() |
| */ |
| int (*write_s64)(struct cgroup_subsys_state *css, struct cftype *cft, |
| s64 val); |
| |
| /* |
| * write() is the generic write callback which maps directly to |
| * kernfs write operation and overrides all other operations. |
| * Maximum write size is determined by ->max_write_len. Use |
| * of_css/cft() to access the associated css and cft. |
| */ |
| ssize_t (*write)(struct kernfs_open_file *of, |
| char *buf, size_t nbytes, loff_t off); |
| |
| #ifdef CONFIG_DEBUG_LOCK_ALLOC |
| struct lock_class_key lockdep_key; |
| #endif |
| }; |
| |
| /* |
| * Control Group subsystem type. |
| * See Documentation/cgroups/cgroups.txt for details |
| */ |
| struct cgroup_subsys { |
| struct cgroup_subsys_state *(*css_alloc)(struct cgroup_subsys_state *parent_css); |
| int (*css_online)(struct cgroup_subsys_state *css); |
| void (*css_offline)(struct cgroup_subsys_state *css); |
| void (*css_released)(struct cgroup_subsys_state *css); |
| void (*css_free)(struct cgroup_subsys_state *css); |
| void (*css_reset)(struct cgroup_subsys_state *css); |
| |
| int (*can_attach)(struct cgroup_taskset *tset); |
| void (*cancel_attach)(struct cgroup_taskset *tset); |
| void (*attach)(struct cgroup_taskset *tset); |
| void (*post_attach)(void); |
| int (*can_fork)(struct task_struct *task); |
| void (*cancel_fork)(struct task_struct *task); |
| void (*fork)(struct task_struct *task); |
| void (*exit)(struct task_struct *task); |
| void (*free)(struct task_struct *task); |
| void (*bind)(struct cgroup_subsys_state *root_css); |
| |
| bool early_init:1; |
| |
| /* |
| * If %true, the controller, on the default hierarchy, doesn't show |
| * up in "cgroup.controllers" or "cgroup.subtree_control", is |
| * implicitly enabled on all cgroups on the default hierarchy, and |
| * bypasses the "no internal process" constraint. This is for |
| * utility type controllers which is transparent to userland. |
| * |
| * An implicit controller can be stolen from the default hierarchy |
| * anytime and thus must be okay with offline csses from previous |
| * hierarchies coexisting with csses for the current one. |
| */ |
| bool implicit_on_dfl:1; |
| |
| /* |
| * If %true, the controller, supports threaded mode on the default |
| * hierarchy. In a threaded subtree, both process granularity and |
| * no-internal-process constraint are ignored and a threaded |
| * controllers should be able to handle that. |
| * |
| * Note that as an implicit controller is automatically enabled on |
| * all cgroups on the default hierarchy, it should also be |
| * threaded. implicit && !threaded is not supported. |
| */ |
| bool threaded:1; |
| |
| /* |
| * If %false, this subsystem is properly hierarchical - |
| * configuration, resource accounting and restriction on a parent |
| * cgroup cover those of its children. If %true, hierarchy support |
| * is broken in some ways - some subsystems ignore hierarchy |
| * completely while others are only implemented half-way. |
| * |
| * It's now disallowed to create nested cgroups if the subsystem is |
| * broken and cgroup core will emit a warning message on such |
| * cases. Eventually, all subsystems will be made properly |
| * hierarchical and this will go away. |
| */ |
| bool broken_hierarchy:1; |
| bool warned_broken_hierarchy:1; |
| |
| /* the following two fields are initialized automtically during boot */ |
| int id; |
| const char *name; |
| |
| /* optional, initialized automatically during boot if not set */ |
| const char *legacy_name; |
| |
| /* link to parent, protected by cgroup_lock() */ |
| struct cgroup_root *root; |
| |
| /* idr for css->id */ |
| struct idr css_idr; |
| |
| /* |
| * List of cftypes. Each entry is the first entry of an array |
| * terminated by zero length name. |
| */ |
| struct list_head cfts; |
| |
| /* |
| * Base cftypes which are automatically registered. The two can |
| * point to the same array. |
| */ |
| struct cftype *dfl_cftypes; /* for the default hierarchy */ |
| struct cftype *legacy_cftypes; /* for the legacy hierarchies */ |
| |
| /* |
| * A subsystem may depend on other subsystems. When such subsystem |
| * is enabled on a cgroup, the depended-upon subsystems are enabled |
| * together if available. Subsystems enabled due to dependency are |
| * not visible to userland until explicitly enabled. The following |
| * specifies the mask of subsystems that this one depends on. |
| */ |
| unsigned int depends_on; |
| }; |
| |
| extern struct percpu_rw_semaphore cgroup_threadgroup_rwsem; |
| |
| /** |
| * cgroup_threadgroup_change_begin - threadgroup exclusion for cgroups |
| * @tsk: target task |
| * |
| * Allows cgroup operations to synchronize against threadgroup changes |
| * using a percpu_rw_semaphore. |
| */ |
| static inline void cgroup_threadgroup_change_begin(struct task_struct *tsk) |
| { |
| percpu_down_read(&cgroup_threadgroup_rwsem); |
| } |
| |
| /** |
| * cgroup_threadgroup_change_end - threadgroup exclusion for cgroups |
| * @tsk: target task |
| * |
| * Counterpart of cgroup_threadcgroup_change_begin(). |
| */ |
| static inline void cgroup_threadgroup_change_end(struct task_struct *tsk) |
| { |
| percpu_up_read(&cgroup_threadgroup_rwsem); |
| } |
| |
| #else /* CONFIG_CGROUPS */ |
| |
| #define CGROUP_SUBSYS_COUNT 0 |
| |
| static inline void cgroup_threadgroup_change_begin(struct task_struct *tsk) |
| { |
| might_sleep(); |
| } |
| |
| static inline void cgroup_threadgroup_change_end(struct task_struct *tsk) {} |
| |
| #endif /* CONFIG_CGROUPS */ |
| |
| #ifdef CONFIG_SOCK_CGROUP_DATA |
| |
| /* |
| * sock_cgroup_data is embedded at sock->sk_cgrp_data and contains |
| * per-socket cgroup information except for memcg association. |
| * |
| * On legacy hierarchies, net_prio and net_cls controllers directly set |
| * attributes on each sock which can then be tested by the network layer. |
| * On the default hierarchy, each sock is associated with the cgroup it was |
| * created in and the networking layer can match the cgroup directly. |
| * |
| * To avoid carrying all three cgroup related fields separately in sock, |
| * sock_cgroup_data overloads (prioidx, classid) and the cgroup pointer. |
| * On boot, sock_cgroup_data records the cgroup that the sock was created |
| * in so that cgroup2 matches can be made; however, once either net_prio or |
| * net_cls starts being used, the area is overriden to carry prioidx and/or |
| * classid. The two modes are distinguished by whether the lowest bit is |
| * set. Clear bit indicates cgroup pointer while set bit prioidx and |
| * classid. |
| * |
| * While userland may start using net_prio or net_cls at any time, once |
| * either is used, cgroup2 matching no longer works. There is no reason to |
| * mix the two and this is in line with how legacy and v2 compatibility is |
| * handled. On mode switch, cgroup references which are already being |
| * pointed to by socks may be leaked. While this can be remedied by adding |
| * synchronization around sock_cgroup_data, given that the number of leaked |
| * cgroups is bound and highly unlikely to be high, this seems to be the |
| * better trade-off. |
| */ |
| struct sock_cgroup_data { |
| union { |
| #ifdef __LITTLE_ENDIAN |
| struct { |
| u8 is_data; |
| u8 padding; |
| u16 prioidx; |
| u32 classid; |
| } __packed; |
| #else |
| struct { |
| u32 classid; |
| u16 prioidx; |
| u8 padding; |
| u8 is_data; |
| } __packed; |
| #endif |
| u64 val; |
| }; |
| }; |
| |
| /* |
| * There's a theoretical window where the following accessors race with |
| * updaters and return part of the previous pointer as the prioidx or |
| * classid. Such races are short-lived and the result isn't critical. |
| */ |
| static inline u16 sock_cgroup_prioidx(const struct sock_cgroup_data *skcd) |
| { |
| /* fallback to 1 which is always the ID of the root cgroup */ |
| return (skcd->is_data & 1) ? skcd->prioidx : 1; |
| } |
| |
| static inline u32 sock_cgroup_classid(const struct sock_cgroup_data *skcd) |
| { |
| /* fallback to 0 which is the unconfigured default classid */ |
| return (skcd->is_data & 1) ? skcd->classid : 0; |
| } |
| |
| /* |
| * If invoked concurrently, the updaters may clobber each other. The |
| * caller is responsible for synchronization. |
| */ |
| static inline void sock_cgroup_set_prioidx(struct sock_cgroup_data *skcd, |
| u16 prioidx) |
| { |
| struct sock_cgroup_data skcd_buf = {{ .val = READ_ONCE(skcd->val) }}; |
| |
| if (sock_cgroup_prioidx(&skcd_buf) == prioidx) |
| return; |
| |
| if (!(skcd_buf.is_data & 1)) { |
| skcd_buf.val = 0; |
| skcd_buf.is_data = 1; |
| } |
| |
| skcd_buf.prioidx = prioidx; |
| WRITE_ONCE(skcd->val, skcd_buf.val); /* see sock_cgroup_ptr() */ |
| } |
| |
| static inline void sock_cgroup_set_classid(struct sock_cgroup_data *skcd, |
| u32 classid) |
| { |
| struct sock_cgroup_data skcd_buf = {{ .val = READ_ONCE(skcd->val) }}; |
| |
| if (sock_cgroup_classid(&skcd_buf) == classid) |
| return; |
| |
| if (!(skcd_buf.is_data & 1)) { |
| skcd_buf.val = 0; |
| skcd_buf.is_data = 1; |
| } |
| |
| skcd_buf.classid = classid; |
| WRITE_ONCE(skcd->val, skcd_buf.val); /* see sock_cgroup_ptr() */ |
| } |
| |
| #else /* CONFIG_SOCK_CGROUP_DATA */ |
| |
| struct sock_cgroup_data { |
| }; |
| |
| #endif /* CONFIG_SOCK_CGROUP_DATA */ |
| |
| #endif /* _LINUX_CGROUP_DEFS_H */ |