linux-kernel - [PATCH 5/5] FRV: Don't make smp_{r, w, }mb() interpolate MEMBAR when CONFIG

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Message-ID: <20080410151105.3764.51970.stgit@warthog.procyon.org.uk>
Date:	Thu, 10 Apr 2008 16:11:05 +0100
From:	David Howells <dhowells@...hat.com>
To:	torvalds@...l.org, akpm@...ux-foundation.org
Cc:	linux-kernel@...r.kernel.org, dhowells@...hat.com
Subject: [PATCH 5/5] FRV: Don't make smp_{r, w,
	}mb() interpolate MEMBAR when CONFIG_SMP=n [try #2]

From: David Howells <dhowells@...hat.com>

Don't make smp_{r,w,}mb() interpolate a MEMBAR instruction when CONFIG_SMP=n as
SMP memory barries on UP systems should interpolate a compiler barrier only.

Signed-off-by: David Howells <dhowells@...hat.com>
---

 include/asm-frv/system.h |   21 +++++++++++++++------
 1 files changed, 15 insertions(+), 6 deletions(-)


diff --git a/include/asm-frv/system.h b/include/asm-frv/system.h
index 2c57f47..30a67a9 100644
--- a/include/asm-frv/system.h
+++ b/include/asm-frv/system.h
@@ -179,14 +179,23 @@ do {							\
 #define mb()			asm volatile ("membar" : : :"memory")
 #define rmb()			asm volatile ("membar" : : :"memory")
 #define wmb()			asm volatile ("membar" : : :"memory")
-#define set_mb(var, value)	do { var = value; mb(); } while (0)
+#define read_barrier_depends()	barrier()
 
-#define smp_mb()		mb()
-#define smp_rmb()		rmb()
-#define smp_wmb()		wmb()
-
-#define read_barrier_depends()		do {} while(0)
+#ifdef CONFIG_SMP
+#define smp_mb()			mb()
+#define smp_rmb()			rmb()
+#define smp_wmb()			wmb()
 #define smp_read_barrier_depends()	read_barrier_depends()
+#define set_mb(var, value) \
+	do { xchg(&var, (value)); } while (0)
+#else
+#define smp_mb()			barrier()
+#define smp_rmb()			barrier()
+#define smp_wmb()			barrier()
+#define smp_read_barrier_depends()	do {} while(0)
+#define set_mb(var, value) \
+	do { var = (value); barrier(); } while (0)
+#endif
 
 #define HARD_RESET_NOW()			\
 do {						\

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