signal: retarget_shared_pending: consider shared/unblocked signals only (f646e227) · Commits · 戴 / test

exit_signals() checks signal_pending() before retarget_shared_pending() but this is suboptimal. We can avoid the while_each_thread() loop in case when there are no shared signals visible to us. Add the "shared_pending.signal & ~blocked" check. We don't use tsk->blocked directly but pass ~blocked as an argument, this is needed for the next patch. Note: we can optimize this more. while_each_thread(t) can check t->blocked into account and stop after every pending signal has the new target, see the next patch. Signed-off-by:

Oleg Nesterov <oleg@redhat.com> Reviewed-by:

Matt Fleming <matt.fleming@linux.intel.com> Acked-by:

Tejun Heo <tj@kernel.org>

kernel/signal.c

+10 −2

Original line number	Diff line number	Diff line
		@@ -2203,10 +2203,15 @@ relock:
		* group-wide signal. Another thread should be notified now to take
		* the signal since we will not.
		*/
		static void retarget_shared_pending(struct task_struct *tsk)
		static void retarget_shared_pending(struct task_struct tsk, sigset_t which)
		{
		sigset_t retarget;
		struct task_struct *t;

		sigandsets(&retarget, &tsk->signal->shared_pending.signal, which);
		if (sigisemptyset(&retarget))
		return;

		t = tsk;
		while_each_thread(tsk, t) {
		if (!signal_pending(t) && !(t->flags & PF_EXITING))
		@@ -2217,6 +2222,7 @@ static void retarget_shared_pending(struct task_struct *tsk)
		void exit_signals(struct task_struct *tsk)
		{
		int group_stop = 0;
		sigset_t unblocked;

		if (thread_group_empty(tsk) \|\| signal_group_exit(tsk->signal)) {
		tsk->flags \|= PF_EXITING;
		@@ -2232,7 +2238,9 @@ void exit_signals(struct task_struct *tsk)
		if (!signal_pending(tsk))
		goto out;

		retarget_shared_pending(tsk);
		unblocked = tsk->blocked;
		signotset(&unblocked);
		retarget_shared_pending(tsk, &unblocked);

		if (unlikely(tsk->group_stop & GROUP_STOP_PENDING) &&
		task_participate_group_stop(tsk))

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