From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: linux-kernel@vger.kernel.org
Cc: mingo@kernel.org, laijs@cn.fujitsu.com, dipankar@in.ibm.com,
akpm@linux-foundation.org, mathieu.desnoyers@efficios.com,
josh@joshtriplett.org, niv@us.ibm.com, tglx@linutronix.de,
peterz@infradead.org, rostedt@goodmis.org, dhowells@redhat.com,
edumazet@google.com, darren@dvhart.com, fweisbec@gmail.com,
oleg@redhat.com, sbw@mit.edu,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Subject: [PATCH v2 tip/core/rcu 3/4] rcu: Make rcu_assign_pointer's assignment volatile and type-safe
Date: Wed, 11 Dec 2013 15:08:47 -0800 [thread overview]
Message-ID: <1386803328-13272-3-git-send-email-paulmck@linux.vnet.ibm.com> (raw)
In-Reply-To: <1386803328-13272-1-git-send-email-paulmck@linux.vnet.ibm.com>
From: Josh Triplett <josh@joshtriplett.org>
The rcu_assign_pointer() primitive needs to use ACCESS_ONCE to make
the assignment to the destination pointer volatile, to protect against
compilers too clever for their own good.
Signed-off-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
include/linux/rcupdate.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 00ad28168ef0..97853cd2d7b4 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -551,7 +551,7 @@ static inline void rcu_preempt_sleep_check(void)
#define __rcu_assign_pointer(p, v, space) \
do { \
smp_wmb(); \
- (p) = (typeof(*v) __force space *)(v); \
+ ACCESS_ONCE(p) = (typeof(*(v)) __force space *)(v); \
} while (0)
--
1.8.1.5
next prev parent reply other threads:[~2013-12-11 23:09 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-12-11 23:08 [PATCH v2 tip/core/rcu 0/4] Documentation changes for 3.14 Paul E. McKenney
2013-12-11 23:08 ` [PATCH v2 tip/core/rcu 1/4] rcu: Add comment on evaluate-once properties of rcu_assign_pointer() Paul E. McKenney
2013-12-11 23:08 ` [PATCH v2 tip/core/rcu 2/4] bonding: Use RCU_INIT_POINTER() for better overhead and for sparse Paul E. McKenney
2013-12-11 23:08 ` Paul E. McKenney [this message]
2013-12-11 23:08 ` [PATCH v2 tip/core/rcu 4/4] rcu: Add an RCU_INITIALIZER for global RCU-protected pointers Paul E. McKenney
2013-12-12 4:10 ` [PATCH v2 tip/core/rcu 0/4] Documentation changes for 3.14 Josh Triplett
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