blob: d4fe9b0a848c150bef1645f84de85fabfa4139b8 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
|
From: Julien Grall <julien.grall@arm.com>
Date: Wed, 21 Aug 2019 10:24:07 +0100
Subject: [PATCH 1/3] hrtimer: Use READ_ONCE to access timer->base in
hrimer_grab_expiry_lock()
Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/5.2/older/patches-5.2.10-rt5.tar.xz
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>
---
kernel/time/hrtimer.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -932,7 +932,7 @@ 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);
|
