Add the rt linux 4.1.3-rt3 as base

[kvmfornfv.git] / kernel / include / asm-generic / bitops / lock.h

diff --git a/kernel/include/asm-generic/bitops/lock.h b/kernel/include/asm-generic/bitops/lock.h
new file mode 100644 (file)
index 0000000..c30266e
--- /dev/null
+++ b/kernel/include/asm-generic/bitops/lock.h
@@ -0,0 +1,45 @@
+#ifndef _ASM_GENERIC_BITOPS_LOCK_H_
+#define _ASM_GENERIC_BITOPS_LOCK_H_
+
+/**
+ * test_and_set_bit_lock - Set a bit and return its old value, for lock
+ * @nr: Bit to set
+ * @addr: Address to count from
+ *
+ * This operation is atomic and provides acquire barrier semantics.
+ * It can be used to implement bit locks.
+ */
+#define test_and_set_bit_lock(nr, addr)        test_and_set_bit(nr, addr)
+
+/**
+ * clear_bit_unlock - Clear a bit in memory, for unlock
+ * @nr: the bit to set
+ * @addr: the address to start counting from
+ *
+ * This operation is atomic and provides release barrier semantics.
+ */
+#define clear_bit_unlock(nr, addr)     \
+do {                                   \
+       smp_mb__before_atomic();        \
+       clear_bit(nr, addr);            \
+} while (0)
+
+/**
+ * __clear_bit_unlock - Clear a bit in memory, for unlock
+ * @nr: the bit to set
+ * @addr: the address to start counting from
+ *
+ * This operation is like clear_bit_unlock, however it is not atomic.
+ * It does provide release barrier semantics so it can be used to unlock
+ * a bit lock, however it would only be used if no other CPU can modify
+ * any bits in the memory until the lock is released (a good example is
+ * if the bit lock itself protects access to the other bits in the word).
+ */
+#define __clear_bit_unlock(nr, addr)   \
+do {                                   \
+       smp_mb();                       \
+       __clear_bit(nr, addr);          \
+} while (0)
+
+#endif /* _ASM_GENERIC_BITOPS_LOCK_H_ */
+