linux-kernel - [tip: timers/core] posix-timers: Set k_itimer:: It

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Message-ID: <168712140508.404.13177458639953476257.tip-bot2@tip-bot2>
Date:   Sun, 18 Jun 2023 20:50:05 -0000
From:   "tip-bot2 for Thomas Gleixner" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Frederic Weisbecker <frederic@...nel.org>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [tip: timers/core] posix-timers: Set k_itimer:: It_signal to NULL on exit()

The following commit has been merged into the timers/core branch of tip:

Commit-ID:     72786ff23d5acb7bf3e2535831b2f1dc55c7f44e
Gitweb:        https://git.kernel.org/tip/72786ff23d5acb7bf3e2535831b2f1dc55c7f44e
Author:        Thomas Gleixner <tglx@...utronix.de>
AuthorDate:    Tue, 25 Apr 2023 20:49:06 +02:00
Committer:     Thomas Gleixner <tglx@...utronix.de>
CommitterDate: Sun, 18 Jun 2023 22:41:49 +02:00

posix-timers: Set k_itimer:: It_signal to NULL on exit()

Technically it's not required to set k_itimer::it_signal to NULL on exit()
because there is no other thread anymore which could lookup the timer
concurrently.

Set it to NULL for consistency sake and add a comment to that effect.

Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Reviewed-by: Frederic Weisbecker <frederic@...nel.org>
Link: https://lore.kernel.org/r/20230425183313.196462644@linutronix.de

---
 kernel/time/posix-timers.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/kernel/time/posix-timers.c b/kernel/time/posix-timers.c
index de3fca8..c1b77c5 100644
--- a/kernel/time/posix-timers.c
+++ b/kernel/time/posix-timers.c
@@ -1101,6 +1101,14 @@ retry_delete:
 	}
 	list_del(&timer->list);
 
+	/*
+	 * Setting timer::it_signal to NULL is technically not required
+	 * here as nothing can access the timer anymore legitimately via
+	 * the hash table. Set it to NULL nevertheless so that all deletion
+	 * paths are consistent.
+	 */
+	WRITE_ONCE(timer->it_signal, NULL);
+
 	spin_unlock_irqrestore(&timer->it_lock, flags);
 	release_posix_timer(timer, IT_ID_SET);
 }