diff mbox series

[v6,09/21] timer: add_timer_on(): Make sure TIMER_PINNED flag is set

Message ID 20230510072817.116056-10-anna-maria@linutronix.de
State New
Headers
Series timer: Move from a push remote at enqueue to a pull at expiry model |

Commit Message

Anna-Maria Behnsen May 10, 2023, 7:28 a.m. UTC 
  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>
---
 kernel/time/timer.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

Comments

Frederic Weisbecker June 5, 2023, 10:12 p.m. UTC | #1 
Le Wed, May 10, 2023 at 09:28:05AM +0200, Anna-Maria Behnsen a écrit :
> 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>

The current users of add_timer_on() don't seem to play nasty
games. Those who use mixes of add_timer_on() and mod_timer()
at least have set TIMER_PINNED on setup time, so looks good.

Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
diff mbox series

Patch

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);
 
 	/*