linux-kernel - [patch V3 15/18] posix-timers: Make per process list RCU safe

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Message-ID: <20250308155624.403223080@linutronix.de>
Date: Sat,  8 Mar 2025 17:48:43 +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>,
 Benjamin Segall <bsegall@...gle.com>,
 Eric Dumazet <edumazet@...gle.com>,
 Andrey Vagin <avagin@...nvz.org>,
 Pavel Tikhomirov <ptikhomirov@...tuozzo.com>,
 Peter Zijlstra <peterz@...radead.org>,
 Cyrill Gorcunov <gorcunov@...il.com>
Subject: [patch V3 15/18] posix-timers: Make per process list RCU safe

Preparatory change to remove the sighand locking from the /proc/$PID/timers
iterator.

Signed-off-by: Thomas Gleixner <tglx@...utronix.de>

---
 kernel/time/posix-timers.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/kernel/time/posix-timers.c
+++ b/kernel/time/posix-timers.c
@@ -518,7 +518,7 @@ static int do_timer_create(clockid_t whi
 		 * Store the unmodified signal pointer to make it valid.
 		 */
 		WRITE_ONCE(new_timer->it_signal, current->signal);
-		hlist_add_head(&new_timer->list, &current->signal->posix_timers);
+		hlist_add_head_rcu(&new_timer->list, &current->signal->posix_timers);
 	}
 	/*
 	 * After unlocking @new_timer is subject to concurrent removal and
@@ -1004,7 +1004,7 @@ static void posix_timer_delete(struct k_
 		unsigned long sig = (unsigned long)timer->it_signal | 1UL;
 
 		WRITE_ONCE(timer->it_signal, (struct signal_struct *)sig);
-		hlist_del(&timer->list);
+		hlist_del_rcu(&timer->list);
 		posix_timer_cleanup_ignored(timer);
 	}