From: Anna-Maria Gleixner <anna-maria@linutronix.de>
Date: Tue, 30 Jul 2019 22:33:49 +0000 (+0200)
Subject: alarmtimer: Prepare for PREEMPT_RT
X-Git-Tag: v5.15~5534^2~64
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=51ae33092bb8320497ec75ddc5ab383d8fafd55c;p=platform%2Fkernel%2Flinux-starfive.git

alarmtimer: Prepare for PREEMPT_RT

Use the hrtimer_cancel_wait_running() synchronization mechanism to prevent
priority inversion and live locks on PREEMPT_RT.

[ tglx: Split out of combo patch ]

Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20190730223828.508744705@linutronix.de
---

diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c
index 57518ef..3694744 100644
--- a/kernel/time/alarmtimer.c
+++ b/kernel/time/alarmtimer.c
@@ -432,7 +432,7 @@ int alarm_cancel(struct alarm *alarm)
 		int ret = alarm_try_to_cancel(alarm);
 		if (ret >= 0)
 			return ret;
-		cpu_relax();
+		hrtimer_cancel_wait_running(&alarm->timer);
 	}
 }
 EXPORT_SYMBOL_GPL(alarm_cancel);