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Commit 932aeafb authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Linus Torvalds
Browse files

[PATCH] fix de_thread vs it_real_fn() deadlock 



de_thread() calls del_timer_sync(->real_timer) under ->sighand->siglock.
This is deadlockable, it_real_fn sends a signal and needs this lock too.

Also, delete unneeded ->real_timer.data assignment.

Signed-off-by: default avatarOleg Nesterov <oleg@tv-sign.ru>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 2f512016

fs/exec.c

+2 −1
Original line number Diff line number Diff line
@@ -641,8 +641,10 @@ static inline int de_thread(struct task_struct *tsk) 
		 * before we can safely let the old group leader die.

		 */

		sig->real_timer.data = (unsigned long)current;

		spin_unlock_irq(lock);

		if (del_timer_sync(&sig->real_timer))

			add_timer(&sig->real_timer);

		spin_lock_irq(lock);

	}

	while (atomic_read(&sig->count) > count) {

		sig->group_exit_task = current;
@@ -654,7 +656,6 @@ static inline int de_thread(struct task_struct *tsk) 
	}

	sig->group_exit_task = NULL;

	sig->notify_count = 0;

	sig->real_timer.data = (unsigned long)current;

	spin_unlock_irq(lock);



	/*