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Commit d2ee7198 authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Linus Torvalds
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pi-futex: set PF_EXITING without taking ->pi_lock 



It is a bit annoying that do_exit() takes ->pi_lock to set PF_EXITING.  All
we need is to synchronize with lookup_pi_state() which saw this task
without PF_EXITING under ->pi_lock.

Change do_exit() to use spin_unlock_wait().

Signed-off-by: default avatarOleg Nesterov <oleg@tv-sign.ru>
Acked-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 7917ff9a

kernel/exit.c

+3 −3
Original line number Diff line number Diff line
@@ -931,13 +931,13 @@ fastcall NORET_TYPE void do_exit(long code) 
		schedule();

	}



	tsk->flags |= PF_EXITING;

	/*

	 * tsk->flags are checked in the futex code to protect against

	 * an exiting task cleaning up the robust pi futexes.

	 */

	spin_lock_irq(&tsk->pi_lock);

	tsk->flags |= PF_EXITING;

	spin_unlock_irq(&tsk->pi_lock);

	smp_mb();

	spin_unlock_wait(&tsk->pi_lock);



	if (unlikely(in_atomic()))

		printk(KERN_INFO "note: %s[%d] exited with preempt_count %d\n",