linux-kernel - [PATCH 10/15] tick: Assume the tick can't be stopped in NOHZ_MODE

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Date: Wed, 24 Jan 2024 18:04:54 +0100
From: Frederic Weisbecker <frederic@...nel.org>
To: LKML <linux-kernel@...r.kernel.org>
Cc: Frederic Weisbecker <frederic@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...nel.org>,
	Anna-Maria Behnsen <anna-maria@...utronix.de>,
	Peng Liu <liupeng17@...ovo.com>,
	Joel Fernandes <joel@...lfernandes.org>
Subject: [PATCH 10/15] tick: Assume the tick can't be stopped in NOHZ_MODE_INACTIVE mode

The full-nohz update function checks if the nohz mode is active before
proceeding. It considers one exception though: if the tick is already
stopped even though the nohz mode is inactive, it still moves on in
order to update/restart the tick if needed.

However in order for the tick to be stopped, the nohz_mode has to be
either NOHZ_MODE_LOWRES or NOHZ_MODE_HIGHRES. Therefore it doesn't make
sense to test if the tick is stopped before verifying NOHZ_MODE_INACTIVE
mode.

Remove the needless related condition.

Signed-off-by: Frederic Weisbecker <frederic@...nel.org>
---
 kernel/time/tick-sched.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index e8e3b5d447e9..3104fff89007 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -1044,7 +1044,7 @@ static void tick_nohz_full_update_tick(struct tick_sched *ts)
 	if (!tick_nohz_full_cpu(smp_processor_id()))
 		return;

-	if (!ts->tick_stopped && ts->nohz_mode == NOHZ_MODE_INACTIVE)
+	if (ts->nohz_mode == NOHZ_MODE_INACTIVE)
 		return;

 	__tick_nohz_full_update_tick(ts, ktime_get());
-- 
2.43.0