[Xen-changelog] [xen-unstable] libxc: Update rmb/wmb for x86.

[Xen patchbot-unstable <patchbot@xxxxxxx>]

# HG changeset patch
# User Keir Fraser <keir@xxxxxxx>
# Date 1327166077 0
# Node ID 475d73479663b7bf85da84a7794df762aa2289a3
# Parent  7f71f0b4b8e66d2c4c95ae7419cd8fb858d6b3df
libxc: Update rmb/wmb for x86.

Only the compiler needs to see the barriers; not the CPU.

Signed-off-by: Keir Fraser <keir@xxxxxxx>
---


diff -r 7f71f0b4b8e6 -r 475d73479663 tools/libxc/xenctrl.h
--- a/tools/libxc/xenctrl.h     Sat Jan 21 16:47:00 2012 +0000
+++ b/tools/libxc/xenctrl.h     Sat Jan 21 17:14:37 2012 +0000
@@ -69,14 +69,16 @@
  *  DEFINITIONS FOR CPU BARRIERS
  */
 
+#define xen_barrier() asm volatile ( "" : : : "memory")
+
 #if defined(__i386__)
 #define xen_mb()  asm volatile ( "lock; addl $0,0(%%esp)" : : : "memory" )
-#define xen_rmb() asm volatile ( "lock; addl $0,0(%%esp)" : : : "memory" )
-#define xen_wmb() asm volatile ( "" : : : "memory")
+#define xen_rmb() xen_barrier()
+#define xen_wmb() xen_barrier()
 #elif defined(__x86_64__)
 #define xen_mb()  asm volatile ( "mfence" : : : "memory")
-#define xen_rmb() asm volatile ( "lfence" : : : "memory")
-#define xen_wmb() asm volatile ( "" : : : "memory")
+#define xen_rmb() xen_barrier()
+#define xen_wmb() xen_barrier()
 #elif defined(__ia64__)
 #define xen_mb()   asm volatile ("mf" ::: "memory")
 #define xen_rmb()  asm volatile ("mf" ::: "memory")

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