[PATCH] complete_signal: kill always-true "core_state || !SIGNAL_GROUP_EXIT" check

[Oleg Nesterov]

The "(signal->core_state || !(signal->flags & SIGNAL_GROUP_EXIT))" check
in complete_signal() is not obvious at all, and in fact it only adds
unnecessary confusion: this condition is always true.

prepare_signal() does:

	if (signal->flags & SIGNAL_GROUP_EXIT) {
		if (signal->core_state)
			return sig == SIGKILL;
		/*
		 * The process is in the middle of dying, drop the signal.
		 */
		return false;
	}

This means that "!signal->core_state && (signal->flags & SIGNAL_GROUP_EXIT)"
in complete_signal() is never possible.

If SIGNAL_GROUP_EXIT is set, prepare_signal() can only return true if
signal->core_state is not NULL.

Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
---
 kernel/signal.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/kernel/signal.c b/kernel/signal.c
index a56a4413699b..683ef92f7234 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1000,9 +1000,7 @@ static void complete_signal(int sig, struct task_struct *p, enum pid_type type)
 	 * Found a killable thread.  If the signal will be fatal,
 	 * then start taking the whole group down immediately.
 	 */
-	if (sig_fatal(p, sig) &&
-	    (signal->core_state || !(signal->flags & SIGNAL_GROUP_EXIT)) &&
-	    !sigismember(&t->real_blocked, sig) &&
+	if (sig_fatal(p, sig) && !sigismember(&t->real_blocked, sig) &&
 	    (sig == SIGKILL || !p->ptrace)) {
 		/*
 		 * This signal will be fatal to the whole group.
-- 
2.52.0