signal: introduce retarget_shared_pending()

No functional changes. Move the notify-other-threads code from exit_signals()
to the new helper, retarget_shared_pending().

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

@@ -2198,10 +2198,25 @@ int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka,
 	return signr;
 }
 
+/*
+ * It could be that complete_signal() picked us to notify about the
+ * 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)
+{
+	struct task_struct *t;
+
+	t = tsk;
+	while_each_thread(tsk, t) {
+		if (!signal_pending(t) && !(t->flags & PF_EXITING))
+			recalc_sigpending_and_wake(t);
+	}
+}
+
 void exit_signals(struct task_struct *tsk)
 {
 	int group_stop = 0;
-	struct task_struct *t;
 
 	if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
 		tsk->flags |= PF_EXITING;
@@ -2217,14 +2232,7 @@ void exit_signals(struct task_struct *tsk)
 	if (!signal_pending(tsk))
 		goto out;
 
-	/*
-	 * It could be that __group_complete_signal() choose us to
-	 * notify about group-wide signal. Another thread should be
-	 * woken now to take the signal since we will not.
-	 */
-	for (t = tsk; (t = next_thread(t)) != tsk; )
-		if (!signal_pending(t) && !(t->flags & PF_EXITING))
-			recalc_sigpending_and_wake(t);
+	retarget_shared_pending(tsk);
 
 	if (unlikely(tsk->group_stop & GROUP_STOP_PENDING) &&
 	    task_participate_group_stop(tsk))