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-rw-r--r--include/linux/bitops.h16
1 files changed, 16 insertions, 0 deletions
diff --git a/include/linux/bitops.h b/include/linux/bitops.h
index defeaac0745f..299e76b59fe9 100644
--- a/include/linux/bitops.h
+++ b/include/linux/bitops.h
@@ -227,6 +227,22 @@ static inline unsigned long __ffs64(u64 word)
})
#endif
+#ifndef bit_clear_unless
+#define bit_clear_unless(ptr, _clear, _test) \
+({ \
+ const typeof(*ptr) clear = (_clear), test = (_test); \
+ typeof(*ptr) old, new; \
+ \
+ do { \
+ old = ACCESS_ONCE(*ptr); \
+ new = old & ~clear; \
+ } while (!(old & test) && \
+ cmpxchg(ptr, old, new) != old); \
+ \
+ !(old & test); \
+})
+#endif
+
#ifndef find_last_bit
/**
* find_last_bit - find the last set bit in a memory region