diff options
| author |   Julien Grall <julien.grall@arm.com> | 2019-08-21 10:24:07 +0100 |
|---|---|---|
| committer |   Thomas Gleixner <tglx@linutronix.de> | 2019-08-21 16:10:01 +0200 |
| commit | dd2261ed45aaeddeb77768f291d604179bcab096 (patch) | |
| tree | 728574e052504dd97511baa14d8db39b46dd4a3e | |
| parent | posix-cpu-timers: Fixup stale comment (diff) | |
| download | linux-dev-dd2261ed45aaeddeb77768f291d604179bcab096.tar.xz linux-dev-dd2261ed45aaeddeb77768f291d604179bcab096.zip | |
hrtimer: Protect lockless access to timer->base
The update to timer->base is protected by the base->cpu_base->lock().
However, hrtimer_cancel_wait_running() does access it lockless. So the
compiler is allowed to refetch timer->base which can cause havoc when the
timer base is changed concurrently.
Use READ_ONCE() to prevent this.
[ tglx: Adapted from a RT patch ]
Signed-off-by: Julien Grall <julien.grall@arm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190821092409.13225-2-julien.grall@arm.com
| -rw-r--r-- | kernel/time/hrtimer.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c index 833353732554..f48864e2ff8a 100644 --- a/kernel/time/hrtimer.c +++ b/kernel/time/hrtimer.c @@ -1214,7 +1214,8 @@ static void hrtimer_sync_wait_running(struct hrtimer_cpu_base *cpu_base, */ void hrtimer_cancel_wait_running(const struct hrtimer *timer) { - struct hrtimer_clock_base *base = timer->base; + /* Lockless read. Prevent the compiler from reloading it below */ + struct hrtimer_clock_base *base = READ_ONCE(timer->base); if (!timer->is_soft || !base || !base->cpu_base) { cpu_relax(); |