[PATCH 01 of 25] bit_lock smp memory barriers

[Andrea Arcangeli <aarcange@redhat.com>]

From: Andrea Arcangeli <aarcange@redhat.com>

Fix bit spinlock to issue the proper memory barries like regular spinlocks.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
---

diff --git a/include/linux/bit_spinlock.h b/include/linux/bit_spinlock.h
--- a/include/linux/bit_spinlock.h
+++ b/include/linux/bit_spinlock.h
@@ -26,6 +26,7 @@ static inline void bit_spin_lock(int bit
 		}
 	}
 #endif
+	smp_mb();
 	__acquire(bitlock);
 }
 
@@ -41,6 +42,7 @@ static inline int bit_spin_trylock(int b
 		return 0;
 	}
 #endif
+	smp_mb();
 	__acquire(bitlock);
 	return 1;
 }
@@ -50,6 +52,7 @@ static inline int bit_spin_trylock(int b
  */
 static inline void bit_spin_unlock(int bitnum, unsigned long *addr)
 {
+	smp_mb();
 #ifdef CONFIG_DEBUG_SPINLOCK
 	BUG_ON(!test_bit(bitnum, addr));
 #endif
@@ -67,6 +70,7 @@ static inline void bit_spin_unlock(int b
  */
 static inline void __bit_spin_unlock(int bitnum, unsigned long *addr)
 {
+	smp_mb();
 #ifdef CONFIG_DEBUG_SPINLOCK
 	BUG_ON(!test_bit(bitnum, addr));
 #endif

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