kthread: call wake_up_process() without the lock being held
Dmitry Adamushko [Tue, 29 Apr 2008 07:59:23 +0000 (00:59 -0700)]
From the POV of synchronization, there should be no need to call
wake_up_process() with the 'kthread_create_lock' being held.

Signed-off-by: Dmitry Adamushko <dmitry.adamushko@gmail.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Andy Whitcroft <apw@shadowen.org>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kernel/kthread.c

index 92cf693..ac72eea 100644 (file)
@@ -144,9 +144,9 @@ struct task_struct *kthread_create(int (*threadfn)(void *data),
 
        spin_lock(&kthread_create_lock);
        list_add_tail(&create.list, &kthread_create_list);
-       wake_up_process(kthreadd_task);
        spin_unlock(&kthread_create_lock);
 
+       wake_up_process(kthreadd_task);
        wait_for_completion(&create.done);
 
        if (!IS_ERR(create.result)) {