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[PATCH] futex_find_get_task(): don't take tasklist_lock

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It is ok to do find_task_by_pid() + get_task_struct() under
rcu_read_lock(), we cand drop tasklist_lock.

Note that testing of ->exit_state is racy with or without tasklist anyway.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Oleg Nesterov 2006-09-29 02:00:55 -07:00 committed by Linus Torvalds
parent 44938af6e0
commit d359b549bf
1 changed files with 2 additions and 2 deletions
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4
kernel/futex.c
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@ -389,7 +389,7 @@ static struct task_struct * futex_find_get_task(pid_t pid)
{ {
struct task_struct *p; struct task_struct *p;
read_lock(&tasklist_lock); rcu_read_lock();
p = find_task_by_pid(pid); p = find_task_by_pid(pid);
if (!p) if (!p)
goto out_unlock; goto out_unlock;
@ -403,7 +403,7 @@ static struct task_struct * futex_find_get_task(pid_t pid)
} }
get_task_struct(p); get_task_struct(p);
out_unlock: out_unlock:
read_unlock(&tasklist_lock); rcu_read_unlock();
return p; return p;
} }