diff options
| -rw-r--r-- | arch/x86/xen/spinlock.c | 9 |
1 files changed, 7 insertions, 2 deletions
diff --git a/arch/x86/xen/spinlock.c b/arch/x86/xen/spinlock.c index 2f91e565192..36a5141108d 100644 --- a/arch/x86/xen/spinlock.c +++ b/arch/x86/xen/spinlock.c @@ -326,8 +326,13 @@ static void xen_spin_unlock(struct raw_spinlock *lock) smp_wmb(); /* make sure no writes get moved after unlock */ xl->lock = 0; /* release lock */ - /* make sure unlock happens before kick */ - barrier(); + /* + * Make sure unlock happens before checking for waiting + * spinners. We need a strong barrier to enforce the + * write-read ordering to different memory locations, as the + * CPU makes no implied guarantees about their ordering. + */ + mb(); if (unlikely(xl->spinners)) xen_spin_unlock_slow(xl); |