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From: Anna-Maria Behnsen <anna-maria@linutronix.de>
To: linux-kernel@vger.kernel.org
Cc: Peter Zijlstra <peterz@infradead.org>,
	John Stultz <jstultz@google.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Eric Dumazet <edumazet@google.com>,
	"Rafael J . Wysocki" <rafael.j.wysocki@intel.com>,
	Arjan van de Ven <arjan@infradead.org>,
	"Paul E . McKenney" <paulmck@kernel.org>,
	Frederic Weisbecker <frederic@kernel.org>,
	Rik van Riel <riel@surriel.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Sebastian Siewior <bigeasy@linutronix.de>,
	Giovanni Gherdovich <ggherdovich@suse.cz>,
	Lukasz Luba <lukasz.luba@arm.com>,
	"Gautham R . Shenoy" <gautham.shenoy@amd.com>,
	Srinivas Pandruvada <srinivas.pandruvada@intel.com>,
	K Prateek Nayak <kprateek.nayak@amd.com>,
	Christian Loehle <christian.loehle@arm.com>,
	Anna-Maria Behnsen <anna-maria@linutronix.de>
Subject: [PATCH v11 15/20] timers: Check if timers base is handled already
Date: Wed, 21 Feb 2024 10:05:43 +0100
Message-Id: <20240221090548.36600-16-anna-maria@linutronix.de>
In-Reply-To: <20240221090548.36600-1-anna-maria@linutronix.de>
References: <20240221090548.36600-1-anna-maria@linutronix.de>
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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@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
---
v10: s/cpu/CPU/ in commit message

v6: Drop double negation
---
 kernel/time/timer.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/kernel/time/timer.c b/kernel/time/timer.c
index 52af50d00ae6..7b9f9ed25fc2 100644
--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -2240,6 +2240,9 @@ 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);
-- 
2.39.2