[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: Oleg Nesterov <[email protected]>
Cc: Roland McGrath <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
This commit is contained in:
Oleg Nesterov 2005-10-30 15:02:17 -08:00 • committed by Linus Torvalds
commit 932aeafbe8

View file

@ -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);
/*