linux-kernel - [tip:timers/urgent] nohz: Fix local_timer_softirq

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Message-ID: <tip-80d20d35af1edd632a5e7a3b9c0ab7ceff92769e@git.kernel.org>
Date:   Tue, 31 Jul 2018 13:13:28 -0700
From:   tip-bot for Anna-Maria Gleixner <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     tglx@...utronix.de, linux-kernel@...r.kernel.org,
        anna-maria@...utronix.de, hpa@...or.com,
        paulmck@...ux.vnet.ibm.com, frederic@...nel.org, mingo@...nel.org,
        bristot@...hat.com
Subject: [tip:timers/urgent] nohz: Fix local_timer_softirq_pending()

Commit-ID:  80d20d35af1edd632a5e7a3b9c0ab7ceff92769e
Gitweb:     https://git.kernel.org/tip/80d20d35af1edd632a5e7a3b9c0ab7ceff92769e
Author:     Anna-Maria Gleixner <anna-maria@...utronix.de>
AuthorDate: Tue, 31 Jul 2018 18:13:58 +0200
Committer:  Thomas Gleixner <tglx@...utronix.de>
CommitDate: Tue, 31 Jul 2018 22:08:44 +0200

nohz: Fix local_timer_softirq_pending()

local_timer_softirq_pending() checks whether the timer softirq is
pending with: local_softirq_pending() & TIMER_SOFTIRQ.

This is wrong because TIMER_SOFTIRQ is the softirq number and not a
bitmask. So the test checks for the wrong bit.

Use BIT(TIMER_SOFTIRQ) instead.

Fixes: 5d62c183f9e9 ("nohz: Prevent a timer interrupt storm in tick_nohz_stop_sched_tick()")
Signed-off-by: Anna-Maria Gleixner <anna-maria@...utronix.de>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Reviewed-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
Reviewed-by: Daniel Bristot de Oliveira <bristot@...hat.com>
Acked-by: Frederic Weisbecker <frederic@...nel.org>
Cc: bigeasy@...utronix.de
Cc: peterz@...radead.org
Cc: stable@...r.kernel.org
Link: https://lkml.kernel.org/r/20180731161358.29472-1-anna-maria@linutronix.de

---
 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 da9455a6b42b..5b33e2f5c0ed 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -642,7 +642,7 @@ static void tick_nohz_restart(struct tick_sched *ts, ktime_t now)

 static inline bool local_timer_softirq_pending(void)
 {
-	return local_softirq_pending() & TIMER_SOFTIRQ;
+	return local_softirq_pending() & BIT(TIMER_SOFTIRQ);
 }

 static ktime_t tick_nohz_next_event(struct tick_sched *ts, int cpu)