46 lines
1.9 KiB
Diff
46 lines
1.9 KiB
Diff
From 5efd46d0f1390fe3f13f0597832fb87dfe62eecd Mon Sep 17 00:00:00 2001
|
|
Message-Id: <5efd46d0f1390fe3f13f0597832fb87dfe62eecd.1601675153.git.zanussi@kernel.org>
|
|
In-Reply-To: <5b5a156f9808b1acf1205606e03da117214549ea.1601675151.git.zanussi@kernel.org>
|
|
References: <5b5a156f9808b1acf1205606e03da117214549ea.1601675151.git.zanussi@kernel.org>
|
|
From: Julien Grall <julien.grall@arm.com>
|
|
Date: Wed, 21 Aug 2019 10:24:07 +0100
|
|
Subject: [PATCH 293/333] hrtimer: Use READ_ONCE to access timer->base in
|
|
hrimer_grab_expiry_lock()
|
|
Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.19/older/patches-4.19.148-rt64.tar.xz
|
|
|
|
[ Upstream commit 2c8fdbe7ef0ad06c1a326886c5954e117b5657d6 ]
|
|
|
|
The update to timer->base is protected by the base->cpu_base->lock().
|
|
However, hrtimer_grab_expirty_lock() does not access it with the lock.
|
|
|
|
So it would theorically be possible to have timer->base changed under
|
|
our feet. We need to prevent the compiler to refetch timer->base so the
|
|
check and the access is performed on the same base.
|
|
|
|
Other access of timer->base are either done with a lock or protected
|
|
with READ_ONCE(). So use READ_ONCE() in hrtimer_grab_expirty_lock().
|
|
|
|
Signed-off-by: Julien Grall <julien.grall@arm.com>
|
|
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
|
|
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
|
|
---
|
|
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 94d97eae0a46..d6026c170c2d 100644
|
|
--- a/kernel/time/hrtimer.c
|
|
+++ b/kernel/time/hrtimer.c
|
|
@@ -941,7 +941,7 @@ EXPORT_SYMBOL_GPL(hrtimer_forward);
|
|
|
|
void hrtimer_grab_expiry_lock(const struct hrtimer *timer)
|
|
{
|
|
- struct hrtimer_clock_base *base = timer->base;
|
|
+ struct hrtimer_clock_base *base = READ_ONCE(timer->base);
|
|
|
|
if (base && base->cpu_base) {
|
|
spin_lock(&base->cpu_base->softirq_expiry_lock);
|
|
--
|
|
2.17.1
|
|
|