[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>

7 files changed, 29 insertions, 3 deletions

diff --git a/drivers/md/kcopyd.c b/drivers/md/kcopyd.c
index ca99979..8b3515f 100644
--- a/drivers/md/kcopyd.c
+++ b/drivers/md/kcopyd.c
@@ -8,6 +8,7 @@
  * completion notification.
  */
 
+#include <asm/types.h>
 #include <asm/atomic.h>
 
 #include <linux/blkdev.h>
diff --git a/fs/nfsctl.c b/fs/nfsctl.c
index 0b14938..0d4cf94 100644
--- a/fs/nfsctl.c
+++ b/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>
diff --git a/include/asm-i386/atomic.h b/include/asm-i386/atomic.h
index de649d3..e2c00c9 100644
--- a/include/asm-i386/atomic.h
+++ b/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
diff --git a/include/asm-x86_64/atomic.h b/include/asm-x86_64/atomic.h
index 4b5cd55..4048508 100644
--- a/include/asm-x86_64/atomic.h
+++ b/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
diff --git a/kernel/audit.c b/kernel/audit.c
index d13ab7d..0a813d2 100644
--- a/kernel/audit.c
+++ b/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>
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index d8a6850..685c251 100644
--- a/kernel/auditsc.c
+++ b/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>
diff --git a/net/ipv4/raw.c b/net/ipv4/raw.c
index 165a4d8..f29a12d 100644
--- a/net/ipv4/raw.c
+++ b/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>