[Xen-devel] [PATCH] Cleanup rmb()/wmb() usage

[Anthony Liguori <aliguori@xxxxxxxxxx>]

This is a pretty simple patch to use the read/write barriers defined in 
asm/system.h instead of using hardcoded versions in various places 
throughout Xen.
I've checked and using asm/system.h generates the same code on my 
system.  I also tested xcs and it seems to work fine.  I haven't tested 
blktap but again, it's generating the same code.
Right now, wmb() is defined as a NOP on any 386 architecture.  Some 
Intel clones require a non-NOP wmb().   Using asm/system.h ensures we do 
the right thing.
It's against xen-unstable as of today.

Regards,
Anthony Liguori

Signed-off-by: Anthony Liguori <aliguori@xxxxxxxxxx>

diff -ur xen-unstable-orig/tools/blktap/blktaplib.h 
xen-unstable/tools/blktap/blktaplib.h
--- xen-unstable-orig/tools/blktap/blktaplib.h  2005-02-21 22:19:26.000000000 
-0600
+++ xen-unstable/tools/blktap/blktaplib.h       2005-02-22 21:26:06.000000000 
-0600
@@ -18,14 +18,9 @@
 typedef int16_t            s16;
 typedef int32_t            s32;
 typedef int64_t            s64;
-                                                                               
 
-#if defined(__i386__)
-#define rmb() __asm__ __volatile__ ( "lock; addl $0,0(%%esp)" : : : "memory" )
-#define wmb() __asm__ __volatile__ ( "" : : : "memory" )
-#else
-#error "Define barriers"
-#endif
-    
+
+#include <asm/system.h>
+
 #include <sys/user.h>
 #include <xen/xen.h>
 #include <xen/io/blkif.h>
diff -ur xen-unstable-orig/tools/python/xen/lowlevel/xu/xu.c 
xen-unstable/tools/python/xen/lowlevel/xu/xu.c
--- xen-unstable-orig/tools/python/xen/lowlevel/xu/xu.c 2005-02-21 
22:19:25.000000000 -0600
+++ xen-unstable/tools/python/xen/lowlevel/xu/xu.c      2005-02-22 
21:23:50.000000000 -0600
@@ -27,6 +27,8 @@
 #include <xen/io/domain_controller.h>
 #include <xen/linux/privcmd.h>
 
+#include <asm/system.h>
+
 #define XENPKG "xen.lowlevel.xu"
 
 /* Needed for Python versions earlier than 2.3. */
@@ -49,14 +51,6 @@
 /* Size of a machine page frame. */
 #define PAGE_SIZE 4096
 
-#if defined(__i386__)
-#define rmb() __asm__ __volatile__ ( "lock; addl $0,0(%%esp)" : : : "memory" )
-#define wmb() __asm__ __volatile__ ( "" : : : "memory" )
-#else
-#error "Define barriers"
-#endif
-
-
 /* Set the close-on-exec flag on a file descriptor.  Doesn't currently bother
  * to check for errors. */
 /*
diff -ur xen-unstable-orig/tools/xcs/xcs.h xen-unstable/tools/xcs/xcs.h
--- xen-unstable-orig/tools/xcs/xcs.h   2005-02-21 22:19:31.000000000 -0600
+++ xen-unstable/tools/xcs/xcs.h        2005-02-22 21:24:12.000000000 -0600
@@ -16,6 +16,7 @@
 #include <xen/io/domain_controller.h>
 #include <xen/linux/privcmd.h>
 #include <sys/time.h>
+#include <asm/system.h>
 #include "xcs_proto.h"
 
 /* ------[ Debug macros ]--------------------------------------------------*/
@@ -39,13 +40,6 @@
 /* Size of a machine page frame. */
 #define PAGE_SIZE 4096
 
-#if defined(__i386__)
-#define rmb() __asm__ __volatile__ ( "lock; addl $0,0(%%esp)" : : : "memory" )
-#define wmb() __asm__ __volatile__ ( "" : : : "memory" )
-#else
-#error "Define barriers"
-#endif
-
 #ifndef timersub /* XOPEN and __BSD don't cooperate well... */
 #define timersub(a, b, result)                                                \
   do {                                                                        \