[PATCH v9 19/32] timers: add_timer_on(): Make sure TIMER_PINNED flag is set

Anna-Maria Behnsen
2023-12-01T09:28:29Z

When adding a timer to the timer wheel using add_timer_on(), it is an
implicitly pinned timer. With the timer pull at expiry time model in place,
TIMER_PINNED flag is required to make sure timers end up in proper base.

Add TIMER_PINNED flag unconditionally when add_timer_on() is executed.

Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
---
kernel/time/timer.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/kernel/time/timer.c b/kernel/time/timer.c
index 0ce0e6b25482..ea94479ee7e2 100644
--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -1284,7 +1284,10 @@ EXPORT_SYMBOL(add_timer_global);
* @timer: The timer to be started
* @cpu: The CPU to start it on
*
- * Same as add_timer() except that it starts the timer on the given CPU.
+ * Same as add_timer() except that it starts the timer on the given CPU and
+ * the TIMER_PINNED flag is set. When timer shouldn't be a pinned timer in
+ * the next round, add_timer_global() should be used instead as it unsets
+ * the TIMER_PINNED flag.
*
* See add_timer() for further details.
*/
@@ -1298,6 +1301,9 @@ void add_timer_on(struct timer_list *timer, int cpu)
if (WARN_ON_ONCE(timer_pending(timer)))
return;

+ /* Make sure timer flags have TIMER_PINNED flag set */
+ timer->flags |= TIMER_PINNED;
+
new_base = get_timer_cpu_base(timer->flags, cpu);

/*
--
2.39.2