[PATCH v7 09/21] timer: add_timer_on(): Make sure TIMER_PINNED flag is set

From: Anna-Maria Behnsen
Date: Wed May 24 2023 - 03:07:40 EST


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@xxxxxxxxxxxxx>
---
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 ab9a8bb11a8a..b7599216d183 100644
--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -1281,7 +1281,10 @@ 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.
*/
@@ -1295,6 +1298,9 @@ 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);

/*
--
2.30.2