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Subject[PATCH tip/core/rcu 2/3] atomic: add atomic_or()
Date
From: Paul E. McKenney <paul.mckenney@linaro.org>

An atomic_or() function is needed by TREE_RCU to avoid deadlock, so
add a generic version.

Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
include/linux/atomic.h | 13 +++++++++++++
1 files changed, 13 insertions(+), 0 deletions(-)
diff --git a/include/linux/atomic.h b/include/linux/atomic.h
index 96c038e..ee456c7 100644
--- a/include/linux/atomic.h
+++ b/include/linux/atomic.h
@@ -34,4 +34,17 @@ static inline int atomic_inc_not_zero_hint(atomic_t *v, int hint)
}
#endif

+#ifndef CONFIG_ARCH_HAS_ATOMIC_OR
+static inline void atomic_or(int i, atomic_t *v)
+{
+ int old;
+ int new;
+
+ do {
+ old = atomic_read(v);
+ new = old | i;
+ } while (atomic_cmpxchg(v, old, new) != old);
+}
+#endif /* #ifndef CONFIG_ARCH_HAS_ATOMIC_OR */
+
#endif /* _LINUX_ATOMIC_H */
--
1.7.3.2


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