From: Jeremy Fitzhardinge <jeremy.fitzhardi...@citrix.com>
Add a barrier() at the end of __raw_spin_unlock() to prevent instructions
from after the locked region from being reordered into it. In theory doing
so shouldn't cause any problems, but in practice, the system locks up
under load...
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardi...@citrix.com>
---
arch/x86/include/asm/spinlock.h | 2 ++
1 files changed, 2 insertions(+), 0 deletions(-)
diff --git a/arch/x86/include/asm/spinlock.h b/arch/x86/include/asm/spinlock.h
index d6de5e7..158b330 100644
--- a/arch/x86/include/asm/spinlock.h
+++ b/arch/x86/include/asm/spinlock.h
@@ -189,6 +189,8 @@ static __always_inline void
arch_spin_unlock(arch_spinlock_t *lock)
next = lock->tickets.head + 1;
__ticket_unlock_release(lock);
__ticket_unlock_kick(lock, next);
+
+ barrier(); /* prevent reordering into locked region */
}
static inline int arch_spin_is_locked(arch_spinlock_t *lock)
--
1.7.2.3
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