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From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: linux-kernel@vger.kernel.org
Cc: mingo@elte.hu, laijs@cn.fujitsu.com, dipankar@in.ibm.com,
	akpm@linux-foundation.org, mathieu.desnoyers@polymtl.ca,
	josh@joshtriplett.org, niv@us.ibm.com, tglx@linutronix.de,
	peterz@infradead.org, rostedt@goodmis.org,
	Valdis.Kletnieks@vt.edu, dhowells@redhat.com,
	eric.dumazet@gmail.com, darren@dvhart.com, patches@linaro.org,
	"Paul E. McKenney" <paul.mckenney@linaro.org>,
	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Subject: [PATCH tip/core/rcu 2/3] atomic: add atomic_or()
Date: Wed, 11 May 2011 13:59:36 -0700	[thread overview]
Message-ID: <1305147577-1812-2-git-send-email-paulmck@linux.vnet.ibm.com> (raw)
In-Reply-To: <20110511205915.GA1731@linux.vnet.ibm.com>

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


  parent reply	other threads:[~2011-05-11 20:59 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-05-11 20:59 [PATCH tip/core/rcu 0/3] Fixes for lockdep and out-of-tree-module build problem Paul E. McKenney
2011-05-11 20:59 ` [PATCH tip/core/rcu 1/3] rcu: avoid build error for third-party modules Paul E. McKenney
2011-05-11 20:59 ` Paul E. McKenney [this message]
2011-05-11 20:59 ` [PATCH tip/core/rcu 3/3] rcu: Avoid acquiring rcu_node locks in timer functions Paul E. McKenney

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