[tip:core/rcu] powerpc: Fix smp_mb__before_spinlock()

[tip-bot for Paul E. McKenney]

Commit-ID:  a76ff6884bfedfafcbb0d9c84c7a6b6a546cba6d
Gitweb:     http://git.kernel.org/tip/a76ff6884bfedfafcbb0d9c84c7a6b6a546cba6d
Author:     Paul E. McKenney <paulmck at linux.vnet.ibm.com>
AuthorDate: Wed, 1 Apr 2015 08:19:59 -0700
Committer:  Paul E. McKenney <paulmck at linux.vnet.ibm.com>
CommitDate: Wed, 27 May 2015 12:58:01 -0700

powerpc: Fix smp_mb__before_spinlock()

Currently, smp_mb__before_spinlock() is defined to be smp_wmb()
in core code, but this is not sufficient on PowerPC.  This patch
therefore supplies an override for the generic definition to
strengthen smp_mb__before_spinlock() to smp_mb(), as is needed
on PowerPC.

Signed-off-by: Paul E. McKenney <paulmck at linux.vnet.ibm.com>
Cc: <linuxppc-dev at lists.ozlabs.org>
---
 arch/powerpc/include/asm/barrier.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/powerpc/include/asm/barrier.h b/arch/powerpc/include/asm/barrier.h
index a3bf5be..1124f59 100644
--- a/arch/powerpc/include/asm/barrier.h
+++ b/arch/powerpc/include/asm/barrier.h
@@ -89,5 +89,6 @@ do {									\
 
 #define smp_mb__before_atomic()     smp_mb()
 #define smp_mb__after_atomic()      smp_mb()
+#define smp_mb__before_spinlock()   smp_mb()
 
 #endif /* _ASM_POWERPC_BARRIER_H */