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

diff --git a/kernel/time/posix-timers.c b/kernel/time/posix-timers.c
index e4c92f42fa5745b07f4ce9647ea11e45d3af49b8..b917a162d84a103bdb308fd32138beafd0691489 100644 (file)
--- 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);
        }