Commit d359b549 authored Sep 29, 2006 by Oleg Nesterov Committed by Linus Torvalds Sep 29, 2006

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



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>

parent 44938af6

kernel/futex.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -389,7 +389,7 @@ static struct task_struct * futex_find_get_task(pid_t pid)
		{
		struct task_struct *p;

		read_lock(&tasklist_lock);
		rcu_read_lock();
		p = find_task_by_pid(pid);
		if (!p)
		goto out_unlock;
		@@ -403,7 +403,7 @@ static struct task_struct * futex_find_get_task(pid_t pid)
		}
		get_task_struct(p);
		out_unlock:
		read_unlock(&tasklist_lock);
		rcu_read_unlock();

		return p;
		}