bdi: wake up concurrent wb_shutdown() callers.

[sfrench/cifs-2.6.git] / include / linux / wait_bit.h

diff --git a/include/linux/wait_bit.h b/include/linux/wait_bit.h
index 9318b2166439ab610b789343f385bcaf42e67cdf..2b0072fa5e92d2eb4ef6d779eb95be3f4d7e9ae3 100644 (file)
--- a/include/linux/wait_bit.h
+++ b/include/linux/wait_bit.h
@@ -305,4 +305,21 @@ do {                                                                       \
        __ret;                                                          \
 })
 
+/**
+ * clear_and_wake_up_bit - clear a bit and wake up anyone waiting on that bit
+ *
+ * @bit: the bit of the word being waited on
+ * @word: the word being waited on, a kernel virtual address
+ *
+ * You can use this helper if bitflags are manipulated atomically rather than
+ * non-atomically under a lock.
+ */
+static inline void clear_and_wake_up_bit(int bit, void *word)
+{
+       clear_bit_unlock(bit, word);
+       /* See wake_up_bit() for which memory barrier you need to use. */
+       smp_mb__after_atomic();
+       wake_up_bit(word, bit);
+}
+
 #endif /* _LINUX_WAIT_BIT_H */