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authorLinus Torvalds <torvalds@linux-foundation.org>2021-08-08 11:53:30 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2021-08-08 11:53:30 -0700
commitcceb634774efca60f8cc57041234f00faf97f22d (patch)
tree1b046122ef1870261e384a492e4fcaeb3130dec5
parent713f0f37e8128e8a0190a98f5a4be71fb32a671a (diff)
parentbb7262b295472eb6858b5c49893954794027cd84 (diff)
Merge tag 'timers-urgent-2021-08-08' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull timer fix from Thomas Gleixner: "A single timer fix: - Prevent a memory ordering issue in the timer expiry code which makes it possible to observe falsely that the callback has been executed already while that's not the case, which violates the guarantee of del_timer_sync()" * tag 'timers-urgent-2021-08-08' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: timers: Move clearing of base::timer_running under base:: Lock
-rw-r--r--kernel/time/timer.c6
1 files changed, 4 insertions, 2 deletions
diff --git a/kernel/time/timer.c b/kernel/time/timer.c
index 9eb11c2209e5..e3d2c23c413d 100644
--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -1265,8 +1265,10 @@ static inline void timer_base_unlock_expiry(struct timer_base *base)
static void timer_sync_wait_running(struct timer_base *base)
{
if (atomic_read(&base->timer_waiters)) {
+ raw_spin_unlock_irq(&base->lock);
spin_unlock(&base->expiry_lock);
spin_lock(&base->expiry_lock);
+ raw_spin_lock_irq(&base->lock);
}
}
@@ -1457,14 +1459,14 @@ static void expire_timers(struct timer_base *base, struct hlist_head *head)
if (timer->flags & TIMER_IRQSAFE) {
raw_spin_unlock(&base->lock);
call_timer_fn(timer, fn, baseclk);
- base->running_timer = NULL;
raw_spin_lock(&base->lock);
+ base->running_timer = NULL;
} else {
raw_spin_unlock_irq(&base->lock);
call_timer_fn(timer, fn, baseclk);
+ raw_spin_lock_irq(&base->lock);
base->running_timer = NULL;
timer_sync_wait_running(base);
- raw_spin_lock_irq(&base->lock);
}
}
}