[PATCH] exit: kill unnecessary thread_group_leader() checks in exit_notify() and do_notify_parent()

[Oleg Nesterov]

thread_group_empty(tsk) is only possible if tsk is a group leader, and
thread_group_empty() already does the thread_group_leader() check.

So it makes no sense to check "thread_group_leader() && thread_group_empty()";
thread_group_empty() alone is enough.

Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
---
 kernel/exit.c   | 8 +++-----
 kernel/signal.c | 3 +--
 2 files changed, 4 insertions(+), 7 deletions(-)

diff --git a/kernel/exit.c b/kernel/exit.c
index 8a87021211ae..79976baaff01 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -748,14 +748,12 @@ static void exit_notify(struct task_struct *tsk, int group_dead)
 	tsk->exit_state = EXIT_ZOMBIE;
 
 	if (unlikely(tsk->ptrace)) {
-		int sig = thread_group_leader(tsk) &&
-				thread_group_empty(tsk) &&
-				!ptrace_reparented(tsk) ?
-			tsk->exit_signal : SIGCHLD;
+		int sig = thread_group_empty(tsk) && !ptrace_reparented(tsk)
+			  ? tsk->exit_signal : SIGCHLD;
 		autoreap = do_notify_parent(tsk, sig);
 	} else if (thread_group_leader(tsk)) {
 		autoreap = thread_group_empty(tsk) &&
-			do_notify_parent(tsk, tsk->exit_signal);
+			   do_notify_parent(tsk, tsk->exit_signal);
 	} else {
 		autoreap = true;
 		/* untraced sub-thread */
diff --git a/kernel/signal.c b/kernel/signal.c
index d65d0fe24bfb..ca23059a947d 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -2178,8 +2178,7 @@ bool do_notify_parent(struct task_struct *tsk, int sig)
 	/* do_notify_parent_cldstop should have been called instead.  */
 	WARN_ON_ONCE(task_is_stopped_or_traced(tsk));
 
-	WARN_ON_ONCE(!tsk->ptrace &&
-	       (tsk->group_leader != tsk || !thread_group_empty(tsk)));
+	WARN_ON_ONCE(!tsk->ptrace && !thread_group_empty(tsk));
 
 	/* ptraced, or group-leader without sub-threads */
 	do_notify_pidfd(tsk);
-- 
2.52.0