[Xen-changelog] [xen-unstable] i386: simplify pte_read_atomic()

[Xen patchbot-unstable <patchbot-unstable@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User Keir Fraser <keir@xxxxxxx>
# Date 1288374181 -3600
# Node ID faca957fd013281cdae648a7f472939eab414920
# Parent  6fae4331d5aab48d6061f4448ab72621367b8bde
i386: simplify pte_read_atomic()

There's no need for a loop here: if the value to be compared against
and the value to be stored are equal, cmpxchg{,8b} act just like a
load anyway.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx>
---
 xen/include/asm-x86/x86_32/page.h |    6 +-----
 1 files changed, 1 insertion(+), 5 deletions(-)

diff -r 6fae4331d5aa -r faca957fd013 xen/include/asm-x86/x86_32/page.h
--- a/xen/include/asm-x86/x86_32/page.h Fri Oct 29 18:42:34 2010 +0100
+++ b/xen/include/asm-x86/x86_32/page.h Fri Oct 29 18:43:01 2010 +0100
@@ -84,11 +84,7 @@ extern unsigned int PAGE_HYPERVISOR_NOCA
 
 #endif
 
-#define pte_read_atomic(ptep) ({                              \
-    intpte_t __pte = *(ptep), __npte;                         \
-    while ( (__npte = cmpxchg(ptep, __pte, __pte)) != __pte ) \
-        __pte = __npte;                                       \
-    __pte; })
+#define pte_read_atomic(ptep) cmpxchg(ptep, 0, 0)
 #define pte_write_atomic(ptep, pte) do {                      \
     intpte_t __pte = *(ptep), __npte;                         \
     while ( (__npte = cmpxchg(ptep, __pte, (pte))) != __pte ) \

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