diff mbox series

[v10,15/20] timers: Check if timers base is handled already

Message ID 20240115143743.27827-16-anna-maria@linutronix.de
State New
Headers
Series timers: Move from a push remote at enqueue to a pull at expiry model |

Commit Message

Anna-Maria Behnsen Jan. 15, 2024, 2:37 p.m. UTC 
  Due to the conversion of the NOHZ timer placement to a pull at expiry
time model, the per CPU timer bases with non pinned timers are no
longer handled only by the local CPU. In case a remote CPU already
expires the non pinned timers base of the local CPU, nothing more
needs to be done by the local CPU. A check at the begin of the expire
timers routine is required, because timer base lock is dropped before
executing the timer callback function.

This is a preparatory work, but has no functional impact right now.

Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
---
v10: s/cpu/CPU/ in commit message

v6: Drop double negation
---
 kernel/time/timer.c | 3 +++
 1 file changed, 3 insertions(+)

Comments

Frederic Weisbecker Jan. 24, 2024, 2:22 p.m. UTC | #1 
Le Mon, Jan 15, 2024 at 03:37:38PM +0100, Anna-Maria Behnsen a écrit :
> Due to the conversion of the NOHZ timer placement to a pull at expiry
> time model, the per CPU timer bases with non pinned timers are no
> longer handled only by the local CPU. In case a remote CPU already
> expires the non pinned timers base of the local CPU, nothing more
> needs to be done by the local CPU. A check at the begin of the expire
> timers routine is required, because timer base lock is dropped before
> executing the timer callback function.
> 
> This is a preparatory work, but has no functional impact right now.
> 
> Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de>

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

Patch

diff --git a/kernel/time/timer.c b/kernel/time/timer.c
index ccb2a5c03b87..eb99297a96fe 100644
--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -2225,6 +2225,9 @@  static inline void __run_timers(struct timer_base *base)
 
 	lockdep_assert_held(&base->lock);
 
+	if (base->running_timer)
+		return;
+
 	while (time_after_eq(jiffies, base->clk) &&
 	       time_after_eq(jiffies, base->next_expiry)) {
 		levels = collect_expired_timers(base, heads);