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authorIngo Molnar <mingo@kernel.org>2015-08-25 09:44:49 +0200
committerIngo Molnar <mingo@kernel.org>2015-08-25 09:44:49 +0200
commitf612a7b1a7f1b5139f228724ce340aac24720591 (patch)
treed75f83de54578908af0484d25bcfcb8e650e1cf2 /kernel
parent9b9412dc7008f360c8e8ed10a654d3c8719f69d8 (diff)
parent12d560f4ea87030667438a169912380be00cea4b (diff)
Merge branch 'for-mingo' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu into core/rcu
Pull RCU cleanup from Paul E. McKenney: "Privatize smp_mb__after_unlock_lock(). This commit moves the definition of smp_mb__after_unlock_lock() to kernel/rcu/tree.h, in recognition of the fact that RCU is the only thing using this, that nothing else is likely to use it, and that it is likely to go away completely." Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/rcu/tree.h12
1 files changed, 12 insertions, 0 deletions
diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h
index 0412030ca882..2e991f8361e4 100644
--- a/kernel/rcu/tree.h
+++ b/kernel/rcu/tree.h
@@ -653,3 +653,15 @@ static inline void rcu_nocb_q_lengths(struct rcu_data *rdp, long *ql, long *qll)
#endif /* #else #ifdef CONFIG_RCU_NOCB_CPU */
}
#endif /* #ifdef CONFIG_RCU_TRACE */
+
+/*
+ * Place this after a lock-acquisition primitive to guarantee that
+ * an UNLOCK+LOCK pair act as a full barrier. This guarantee applies
+ * if the UNLOCK and LOCK are executed by the same CPU or if the
+ * UNLOCK and LOCK operate on the same lock variable.
+ */
+#ifdef CONFIG_PPC
+#define smp_mb__after_unlock_lock() smp_mb() /* Full ordering for lock. */
+#else /* #ifdef CONFIG_PPC */
+#define smp_mb__after_unlock_lock() do { } while (0)
+#endif /* #else #ifdef CONFIG_PPC */