linux-kernel - [PATCH RT 09/32] hrtimer: Dont grab the expiry lock for non-soft hrtimer

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Message-Id: <20200117174128.650393932@goodmis.org>
Date:   Fri, 17 Jan 2020 12:41:20 -0500
From:   Steven Rostedt <rostedt@...dmis.org>
To:     linux-kernel@...r.kernel.org,
        linux-rt-users <linux-rt-users@...r.kernel.org>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Carsten Emde <C.Emde@...dl.org>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        John Kacur <jkacur@...hat.com>,
        Julia Cartwright <julia@...com>,
        Daniel Wagner <wagi@...om.org>,
        Tom Zanussi <zanussi@...nel.org>,
        Julien Grall <julien.grall@....com>
Subject: [PATCH RT 09/32] hrtimer: Dont grab the expiry lock for non-soft hrtimer

4.19.94-rt39-rc1 stable review patch.
If anyone has any objections, please let me know.

------------------

From: Julien Grall <julien.grall@....com>

[ Upstream commit fd420354bea2f57c11f3de191dffdeea76531e76 ]

Acquiring the lock in hrtimer_grab_expiry_lock() is designed for
sleeping-locks and should not be used with disabled interrupts.
hrtimer_cancel() may invoke hrtimer_grab_expiry_lock() also for locks
which expire in hard-IRQ context.

Let hrtimer_cancel() invoke hrtimer_grab_expiry_lock() only for locks
which expire in softirq context.

Signed-off-by: Julien Grall <julien.grall@....com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@...dmis.org>
[bigeasy: rewrite changelog]
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
---
 kernel/time/hrtimer.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
index d6026c170c2d..49d20fe8570f 100644
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -943,7 +943,7 @@ void hrtimer_grab_expiry_lock(const struct hrtimer *timer)
 {
 	struct hrtimer_clock_base *base = READ_ONCE(timer->base);
 
-	if (base && base->cpu_base) {
+	if (timer->is_soft && base && base->cpu_base) {
 		spin_lock(&base->cpu_base->softirq_expiry_lock);
 		spin_unlock(&base->cpu_base->softirq_expiry_lock);
 	}
-- 
2.24.1