timers: Fix warning condition in __run_timers()

commit c54bc0fc84214b203f7a0ebfd1bd308ce2abe920 upstream.

When the timer base is empty, base::next_expiry is set to base::clk +
NEXT_TIMER_MAX_DELTA and base::next_expiry_recalc is false. When no timer
is queued until jiffies reaches base::next_expiry value, the warning for
not finding any expired timer and base::next_expiry_recalc is false in
__run_timers() triggers.

To prevent triggering the warning in this valid scenario
base::timers_pending needs to be added to the warning condition.

Fixes: 31cd0e119d50 ("timers: Recalculate next timer interrupt only when necessary")
Reported-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20220405191732.7438-3-anna-maria@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/kernel/time/timer.c b/kernel/time/timer.c
index 85f1021..9dd2a39 100644 (file)
--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -1722,11 +1722,14 @@ static inline void __run_timers(struct timer_base *base)
               time_after_eq(jiffies, base->next_expiry)) {
                levels = collect_expired_timers(base, heads);
                /*
-                * The only possible reason for not finding any expired
-                * timer at this clk is that all matching timers have been
-                * dequeued.
+                * The two possible reasons for not finding any expired
+                * timer at this clk are that all matching timers have been
+                * dequeued or no timer has been queued since
+                * base::next_expiry was set to base::clk +
+                * NEXT_TIMER_MAX_DELTA.
                 */
-               WARN_ON_ONCE(!levels && !base->next_expiry_recalc);
+               WARN_ON_ONCE(!levels && !base->next_expiry_recalc
+                            && base->timers_pending);
                base->clk++;
                base->next_expiry = __next_timer_interrupt(base);