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Subject[PATCH 1/2] posix timers: sigqueue_free: don't free sigqueue if it is queued
Currently sigqueue_free() removes sigqueue from list, but doesn't cancel the
pending signal. This is not consistent, the task should either receive the
"full" signal along with siginfo_t, or it shouldn't receive the signal at all.

Change sigqueue_free() to clear SIGQUEUE_PREALLOC but leave sigqueue on list
if it is queued.

This is a user-visible change. If the signal is blocked, it stays queued
after sys_timer_delete() until unblocked with the "stale" si_code/si_value,
and of course it is still counted wrt RLIMIT_SIGPENDING which also limits
the number of posix timers.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>

--- 26-rc2/kernel/signal.c~1_SF_DONT_REMOVE 2008-05-26 18:09:12.000000000 +0400
+++ 26-rc2/kernel/signal.c 2008-05-26 18:13:08.000000000 +0400
@@ -1240,18 +1240,22 @@ void sigqueue_free(struct sigqueue *q)

BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
/*
- * If the signal is still pending remove it from the
- * pending queue. We must hold ->siglock while testing
- * q->list to serialize with collect_signal() or with
+ * We must hold ->siglock while testing q->list
+ * to serialize with collect_signal() or with
* __exit_signal()->flush_sigqueue().
*/
spin_lock_irqsave(lock, flags);
+ q->flags &= ~SIGQUEUE_PREALLOC;
+ /*
+ * If it is queued it will be freed when dequeued,
+ * like the "regular" sigqueue.
+ */
if (!list_empty(&q->list))
- list_del_init(&q->list);
+ q = NULL;
spin_unlock_irqrestore(lock, flags);

- q->flags &= ~SIGQUEUE_PREALLOC;
- __sigqueue_free(q);
+ if (q)
+ __sigqueue_free(q);
}

int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group)


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