[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 <oleg@tv-sign.ru> Cc: Roland McGrath <roland@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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@ -641,8 +641,10 @@ static inline int de_thread(struct task_struct *tsk)
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* before we can safely let the old group leader die.
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*/
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sig->real_timer.data = (unsigned long)current;
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spin_unlock_irq(lock);
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if (del_timer_sync(&sig->real_timer))
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add_timer(&sig->real_timer);
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spin_lock_irq(lock);
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}
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while (atomic_read(&sig->count) > count) {
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sig->group_exit_task = current;
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@ -654,7 +656,6 @@ static inline int de_thread(struct task_struct *tsk)
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}
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sig->group_exit_task = NULL;
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sig->notify_count = 0;
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sig->real_timer.data = (unsigned long)current;
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spin_unlock_irq(lock);
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/*
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