From 2367e28e231af05243b92325de9a38956ad0b565 Mon Sep 17 00:00:00 2001
From: Anna-Maria Behnsen <anna-maria@linutronix.de>
Date: Tue, 16 Jul 2024 16:19:25 +0200
Subject: [PATCH] timers/migration: Spare write when nothing changed
The wakeup value is written unconditionally in tmigr_cpu_new_timer(). When
there was no new next timer expiry that needs to be propagated, then the
value that was read before is written. This is not required.
Move the write to the place where wakeup value is changed changed.
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/20240716-tmigr-fixes-v4-7-757baa7803fe@linutronix.de
---
kernel/time/timer_migration.c | 11 +++++------
1 file changed, 5 insertions(+), 6 deletions(-)
diff --git a/kernel/time/timer_migration.c b/kernel/time/timer_migration.c
index ca76120ee7c6a..9c15ae8d8a253 100644
--- a/kernel/time/timer_migration.c
+++ b/kernel/time/timer_migration.c
@@ -1215,14 +1215,13 @@ u64 tmigr_cpu_new_timer(u64 nextexp)
if (nextexp != tmc->cpuevt.nextevt.expires ||
tmc->cpuevt.ignore) {
ret = tmigr_new_timer(tmc, nextexp);
+ /*
+ * Make sure the reevaluation of timers in idle path
+ * will not miss an event.
+ */
+ WRITE_ONCE(tmc->wakeup, ret);
}
}
- /*
- * Make sure the reevaluation of timers in idle path will not miss an
- * event.
- */
- WRITE_ONCE(tmc->wakeup, ret);
-
trace_tmigr_cpu_new_timer_idle(tmc, nextexp);
raw_spin_unlock(&tmc->lock);
return ret;
--
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