[tip: timers/core] posix-timers: Make per process list RCU safe

[tip-bot2 for Thomas Gleixner]

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

Commit-ID:     451898ea422b5861d95089d8d9c2a0ab8383775e
Gitweb:        https://git.kernel.org/tip/451898ea422b5861d95089d8d9c2a0ab8383775e
Author:        Thomas Gleixner <tglx@xxxxxxxxxxxxx>
AuthorDate:    Sat, 08 Mar 2025 17:48:43 +01:00
Committer:     Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitterDate: Thu, 13 Mar 2025 12:07:18 +01:00

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@xxxxxxxxxxxxx>
Reviewed-by: Frederic Weisbecker <frederic@xxxxxxxxxx>
Link: https://lore.kernel.org/all/20250308155624.403223080@xxxxxxxxxxxxx


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

diff --git a/kernel/time/posix-timers.c b/kernel/time/posix-timers.c
index e4c92f4..b917a16 100644
--- a/kernel/time/posix-timers.c
+++ b/kernel/time/posix-timers.c
@@ -518,7 +518,7 @@ static int do_timer_create(clockid_t which_clock, struct sigevent *event,
 		 * 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_itimer *timer)
 		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);
 	}