linux-kernel - [patch V7 01/21] posix-cpu-timers: Correctly update timer status in posix_cpu_timer

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Message-ID: <20241105064212.974053438@linutronix.de>
Date: Tue,  5 Nov 2024 09:14:29 +0100 (CET)
From: Thomas Gleixner <tglx@...utronix.de>
To: LKML <linux-kernel@...r.kernel.org>
Cc: Anna-Maria Behnsen <anna-maria@...utronix.de>,
 Frederic Weisbecker <frederic@...nel.org>,
 John Stultz <jstultz@...gle.com>,
 Peter Zijlstra <peterz@...radead.org>,
 Ingo Molnar <mingo@...nel.org>,
 Stephen Boyd <sboyd@...nel.org>,
 Eric Biederman <ebiederm@...ssion.com>,
 Oleg Nesterov <oleg@...hat.com>
Subject: [patch V7 01/21] posix-cpu-timers: Correctly update timer status in
 posix_cpu_timer_del()

If posix_cpu_timer_del() exits early due to task not found or sighand
invalid, it fails to clear the state of the timer. That's harmless but
inconsistent.

These early exits are accounted as successful delete. Move the update of
the timer state into the success return path, so all "successful" deletions
are handled.

Reported-by: Frederic Weisbecker <frederic@...nel.org>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
---
V7: New patch
---
 kernel/time/posix-cpu-timers.c |   12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

--- a/kernel/time/posix-cpu-timers.c
+++ b/kernel/time/posix-cpu-timers.c
@@ -493,20 +493,20 @@ static int posix_cpu_timer_del(struct k_
 		 */
 		WARN_ON_ONCE(ctmr->head || timerqueue_node_queued(&ctmr->node));
 	} else {
-		if (timer->it.cpu.firing) {
+		if (timer->it.cpu.firing)
 			ret = TIMER_RETRY;
-		} else {
+		else
 			disarm_timer(timer, p);
-			timer->it_status = POSIX_TIMER_DISARMED;
-		}
 		unlock_task_sighand(p, &flags);
 	}
 
 out:
 	rcu_read_unlock();
-	if (!ret)
-		put_pid(ctmr->pid);
 
+	if (!ret) {
+		put_pid(ctmr->pid);
+		timer->it_status = POSIX_TIMER_DISARMED;
+	}
 	return ret;
 }