summaryrefslogtreecommitdiff
path: root/kernel/rcu/tree.h
diff options
context:
space:
mode:
authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2015-07-14 18:35:23 -0700
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2015-08-04 08:49:21 -0700
commit12d560f4ea87030667438a169912380be00cea4b (patch)
tree3b60a7b97e849bd68573db48dd8608cb43f05694 /kernel/rcu/tree.h
parent3dbe43f6fba9f2a0e46e371733575a45704c22ab (diff)
downloadlinux-sh-12d560f4ea87030667438a169912380be00cea4b.tar.gz
rcu,locking: Privatize smp_mb__after_unlock_lock()
RCU is the only thing that uses smp_mb__after_unlock_lock(), and is likely the only thing that ever will use it, so this commit makes this macro private to RCU. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: "linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>
Diffstat (limited to 'kernel/rcu/tree.h')
-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 */