linux-kernel - [PATCH 05/26] exit: Remove the pointless clearing of SIGPENDING in __exit

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Date:   Tue,  6 Jun 2017 14:03:17 -0500
From:   "Eric W. Biederman" <ebiederm@...ssion.com>
To:     linux-kernel@...r.kernel.org
Cc:     linux-api@...r.kernel.org,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Oleg Nesterov <oleg@...hat.com>,
        Ingo Molnar <mingo@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Kees Cook <keescook@...omium.org>,
        Roland McGrath <roland@...k.frob.com>,
        Al Viro <viro@...IV.linux.org.uk>,
        David Howells <dhowells@...hat.com>,
        "Michael Kerrisk (man-pages)" <mtk.manpages@...il.com>,
        "Eric W. Biederman" <ebiederm@...ssion.com>
Subject: [PATCH 05/26] exit:  Remove the pointless clearing of SIGPENDING in __exit_signal

Handling of signals does not happen once do_exit is called as a
process never again exits from the kernel.  So remove this ancient hold
over from something else.

Furthermore this is TIF_SIGPENDING on a zombie.  Which will never
be scheduled on a cpu again.

Setting sigpending=0 was silly in 2.4 when exit_sighand did it and was
called from do_exit.  When exit_sighand started being called from
release_task the code went from silly to completely pointless.

History  tree: https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git/
Fixes: 6dfc88977e42 ("[PATCH] shared thread signals")
Signed-off-by: Eric W. Biederman <ebiederm@...ssion.com>
---
 kernel/exit.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/kernel/exit.c b/kernel/exit.c
index 8926cdd132f2..c3de7ace243c 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -164,7 +164,6 @@ static void __exit_signal(struct task_struct *tsk)
 	spin_unlock(&sighand->siglock);
 
 	__cleanup_sighand(sighand);
-	clear_tsk_thread_flag(tsk, TIF_SIGPENDING);
 	if (group_dead) {
 		flush_sigqueue(&sig->shared_pending);
 		tty_kref_put(tty);
-- 
2.10.1