[tip: timers/core] timers: Check if timers base is handled already

[tip-bot2 for Anna-Maria Behnsen]

The following commit has been merged into the timers/core branch of tip:

Commit-ID:     89f01e10c99a5ca2ff88b545fad763d360cdbfc8
Gitweb:        https://git.kernel.org/tip/89f01e10c99a5ca2ff88b545fad763d360cdbfc8
Author:        Anna-Maria Behnsen <anna-maria@xxxxxxxxxxxxx>
AuthorDate:    Wed, 21 Feb 2024 10:05:43 +01:00
Committer:     Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitterDate: Thu, 22 Feb 2024 17:52:32 +01:00

timers: Check if timers base is handled already

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@xxxxxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Reviewed-by: Frederic Weisbecker <frederic@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20240221090548.36600-16-anna-maria@xxxxxxxxxxxxx

---
 kernel/time/timer.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/kernel/time/timer.c b/kernel/time/timer.c
index 51053af..4420cdf 100644
--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -2285,6 +2285,9 @@ 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);