[PATCH] EDAC: atomic scrub operations

EDAC requires a way to scrub memory if an ECC error is found and the chipset
does not do the work automatically.  That means rewriting memory locations
atomically with respect to all CPUs _and_ bus masters.  That means we can't
use atomic_add(foo, 0) as it gets optimised for non-SMP

This adds a function to include/asm-foo/atomic.h for the platforms currently
supported which implements a scrub of a mapped block.

It also adjusts a few other files include order where atomic.h is included
before types.h as this now causes an error as atomic_scrub uses u32.

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

drivers/md/kcopyd.c

@@ -8,6 +8,7 @@
  * completion notification.
  */
 
+#include <asm/types.h>
 #include <asm/atomic.h>
 
 #include <linux/blkdev.h>

fs/nfsctl.c

@@ -5,6 +5,7 @@
  *
  */
 #include <linux/config.h>
+#include <linux/types.h>
 #include <linux/file.h>
 #include <linux/fs.h>
 #include <linux/sunrpc/svc.h>

include/asm-i386/atomic.h

@@ -255,5 +255,17 @@ __asm__ __volatile__(LOCK "orl %0,%1" \
 #define smp_mb__before_atomic_inc()	barrier()
 #define smp_mb__after_atomic_inc()	barrier()
 
+/* ECC atomic, DMA, SMP and interrupt safe scrub function */
+
+static __inline__ void atomic_scrub(unsigned long *virt_addr, u32 size)
+{
+	u32 i;
+	for (i = 0; i < size / 4; i++, virt_addr++)
+		/* Very carefully read and write to memory atomically
+		 * so we are interrupt, DMA and SMP safe.
+		 */
+		__asm__ __volatile__("lock; addl $0, %0"::"m"(*virt_addr));
+}
+
 #include <asm-generic/atomic.h>
 #endif

include/asm-x86_64/atomic.h

@@ -426,5 +426,17 @@ __asm__ __volatile__(LOCK "orl %0,%1" \
 #define smp_mb__before_atomic_inc()	barrier()
 #define smp_mb__after_atomic_inc()	barrier()
 
+/* ECC atomic, DMA, SMP and interrupt safe scrub function */
+
+static __inline__ void atomic_scrub(u32 *virt_addr, u32 size)
+{
+	u32 i;
+	for (i = 0; i < size / 4; i++, virt_addr++)
+		/* Very carefully read and write to memory atomically
+		 * so we are interrupt, DMA and SMP safe.
+		 */
+		__asm__ __volatile__("lock; addl $0, %0"::"m"(*virt_addr));
+}
+
 #include <asm-generic/atomic.h>
 #endif

kernel/audit.c

@@ -42,8 +42,8 @@
  */
 
 #include <linux/init.h>
-#include <asm/atomic.h>
 #include <asm/types.h>
+#include <asm/atomic.h>
 #include <linux/mm.h>
 #include <linux/module.h>
 #include <linux/err.h>

kernel/auditsc.c

@@ -30,8 +30,8 @@
  */
 
 #include <linux/init.h>
-#include <asm/atomic.h>
 #include <asm/types.h>
+#include <asm/atomic.h>
 #include <linux/mm.h>
 #include <linux/module.h>
 #include <linux/mount.h>

net/ipv4/raw.c

@@ -40,12 +40,12 @@
  */
 
 #include <linux/config.h> 
+#include <linux/types.h>
 #include <asm/atomic.h>
 #include <asm/byteorder.h>
 #include <asm/current.h>
 #include <asm/uaccess.h>
 #include <asm/ioctls.h>
-#include <linux/types.h>
 #include <linux/stddef.h>
 #include <linux/slab.h>
 #include <linux/errno.h>