linux-kernel - [tip: timers/core] tick: Assume the tick can't be stopped in NOHZ_MODE

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Date: Mon, 26 Feb 2024 22:24:33 -0000
From: "tip-bot2 for Frederic Weisbecker" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Frederic Weisbecker <frederic@...nel.org>,
 Thomas Gleixner <tglx@...utronix.de>, x86@...nel.org,
 linux-kernel@...r.kernel.org
Subject: [tip: timers/core] tick: Assume the tick can't be stopped in
 NOHZ_MODE_INACTIVE mode

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

Commit-ID:     d9b1865c86aec7c515db5718e4820106c2c12db3
Gitweb:        https://git.kernel.org/tip/d9b1865c86aec7c515db5718e4820106c2c12db3
Author:        Frederic Weisbecker <frederic@...nel.org>
AuthorDate:    Sun, 25 Feb 2024 23:55:02 +01:00
Committer:     Thomas Gleixner <tglx@...utronix.de>
CommitterDate: Mon, 26 Feb 2024 11:37:32 +01:00

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>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Reviewed-by: Thomas Gleixner <tglx@...utronix.de>
Link: https://lore.kernel.org/r/20240225225508.11587-11-frederic@kernel.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 b17895d..b79f540 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -1086,7 +1086,7 @@ 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());