linux-kernel - [tip:timers/core] posix-timers: Remove "it_signal = NULL" assignment in itimer

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Message-ID: <tip-12063d431078be73d11cb5e48a17c6db5f0d8254@git.kernel.org>
Date:   Sat, 22 Jun 2019 12:30:29 -0700
From:   tip-bot for Sebastian Andrzej Siewior <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     hpa@...or.com, bigeasy@...utronix.de, linux-kernel@...r.kernel.org,
        tglx@...utronix.de, mingo@...nel.org
Subject: [tip:timers/core] posix-timers: Remove "it_signal = NULL"
 assignment in itimer_delete()

Commit-ID:  12063d431078be73d11cb5e48a17c6db5f0d8254
Gitweb:     https://git.kernel.org/tip/12063d431078be73d11cb5e48a17c6db5f0d8254
Author:     Sebastian Andrzej Siewior <bigeasy@...utronix.de>
AuthorDate: Fri, 21 Jun 2019 16:36:42 +0200
Committer:  Thomas Gleixner <tglx@...utronix.de>
CommitDate: Sat, 22 Jun 2019 12:14:22 +0200

posix-timers: Remove "it_signal = NULL" assignment in itimer_delete()

itimer_delete() is invoked during do_exit(). At this point it is the
last thread in the group dying and doing the clean up.
Since it is the last thread in the group, there can not be any other
task attempting to lock the itimer which means the NULL assignment (which
avoids lookups in __lock_timer()) is not required.

The assignment and comment was copied in commit 0e568881178ff ("[PATCH]
fix posix-timers to have proper per-process scope") from
sys_timer_delete() which was/is the syscall interface and requires the
assignment.

Remove the superfluous ->it_signal = NULL assignment.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Link: https://lkml.kernel.org/r/20190621143643.25649-2-bigeasy@linutronix.de

---
 kernel/time/posix-timers.c | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/kernel/time/posix-timers.c b/kernel/time/posix-timers.c
index 29176635991f..caa63e58e3d8 100644
--- a/kernel/time/posix-timers.c
+++ b/kernel/time/posix-timers.c
@@ -990,11 +990,6 @@ retry_delete:
 		goto retry_delete;
 	}
 	list_del(&timer->list);
-	/*
-	 * This keeps any tasks waiting on the spin lock from thinking
-	 * they got something (see the lock code above).
-	 */
-	timer->it_signal = NULL;
 
 	unlock_timer(timer, flags);
 	release_posix_timer(timer, IT_ID_SET);