From 55c2945aa9d4d907ec5ca4f6a4e30ae908d8d30d Mon Sep 17 00:00:00 2001
From: "Paul E. McKenney" <paul.mckenney@linaro.org>
Date: Wed, 11 May 2011 05:33:33 -0700
Subject: atomic: Add atomic_or()

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>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
 include/linux/atomic.h | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/include/linux/atomic.h b/include/linux/atomic.h
index 96c038e43d6..ee456c79b0e 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 */
-- 
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