From: Chris Snook <csnook@redhat.com>
To: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org,
torvalds@linux-foundation.org
Cc: netdev@vger.kernel.org, akpm@linux-foundation.org, ak@suse.de,
heiko.carstens@de.ibm.com, davem@davemloft.net,
schwidefsky@de.ibm.com, wensong@linux-vs.org, horms@verge.net.au,
wjiang@resilience.com, cfriesen@nortel.com, zlynx@acm.org,
rpjday@mindspring.com, jesper.juhl@gmail.com
Subject: [PATCH 17/24] make atomic_read() behave consistently on sh64
Date: Thu, 9 Aug 2007 10:09:08 -0400 [thread overview]
Message-ID: <20070809140908.GA18208@shell.boston.redhat.com> (raw)
From: Chris Snook <csnook@redhat.com>
Purify volatile use for atomic_t on sh64.
Signed-off-by: Chris Snook <csnook@redhat.com>
--- linux-2.6.23-rc2-orig/include/asm-sh64/atomic.h 2007-07-08 19:32:17.000000000 -0400
+++ linux-2.6.23-rc2/include/asm-sh64/atomic.h 2007-08-09 07:22:50.000000000 -0400
@@ -19,11 +19,15 @@
*
*/
-typedef struct { volatile int counter; } atomic_t;
+typedef struct { int counter; } atomic_t;
#define ATOMIC_INIT(i) ( (atomic_t) { (i) } )
-#define atomic_read(v) ((v)->counter)
+/*
+ * Casting to volatile here minimizes the need for barriers,
+ * without having to declare the type itself as volatile.
+ */
+#define atomic_read(v) (*(volatile int *)&(v)->counter)
#define atomic_set(v,i) ((v)->counter = (i))
#include <asm/system.h>
next prev reply other threads:[~2007-08-09 14:09 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-08-09 14:10 [PATCH 18/24] make atomic_read() behave consistently on sh Chris Snook
2007-08-09 14:09 ` Chris Snook [this message]
2007-08-09 16:40 ` [PATCH 17/24] make atomic_read() behave consistently on sh64 Paul Mundt
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