[PATCH] pids: kill PIDTYPE_TGID
This patch kills PIDTYPE_TGID pid_type thus saving one hash table in
kernel/pid.c and speeding up subthreads create/destroy a bit. It is also a
preparation for the further tref/pids rework.
This patch adds 'struct list_head thread_group' to 'struct task_struct'
instead.
We don't detach group leader from PIDTYPE_PID namespace until another
thread inherits it's ->pid == ->tgid, so we are safe wrt premature
free_pidmap(->tgid) call.
Currently there are no users of find_task_by_pid_type(PIDTYPE_TGID).
Should the need arise, we can use find_task_by_pid()->group_leader.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Acked-By: Eric Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/include/linux/sched.h b/include/linux/sched.h
index a913fca..99855f6 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -752,6 +752,7 @@
/* PID/PID hash table linkage. */
struct pid pids[PIDTYPE_MAX];
+ struct list_head thread_group;
struct completion *vfork_done; /* for vfork() */
int __user *set_child_tid; /* CLONE_CHILD_SETTID */
@@ -1192,13 +1193,17 @@
#define while_each_thread(g, t) \
while ((t = next_thread(t)) != g)
-extern task_t * FASTCALL(next_thread(const task_t *p));
-
#define thread_group_leader(p) (p->pid == p->tgid)
+static inline task_t *next_thread(task_t *p)
+{
+ return list_entry(rcu_dereference(p->thread_group.next),
+ task_t, thread_group);
+}
+
static inline int thread_group_empty(task_t *p)
{
- return list_empty(&p->pids[PIDTYPE_TGID].pid_list);
+ return list_empty(&p->thread_group);
}
#define delay_group_leader(p) \
