[Xen-changelog] [xen master] xen: arm32: ensure cmpxchg has full barrier semantics

[patchbot@xxxxxxx]

commit ade960be492d0c12648fe86a121808d27adab8f9
Author:     Ian Campbell <ian.campbell@xxxxxxxxxx>
AuthorDate: Wed Mar 26 13:38:38 2014 +0000
Commit:     Ian Campbell <ian.campbell@xxxxxxxxxx>
CommitDate: Thu Apr 3 17:15:41 2014 +0100

    xen: arm32: ensure cmpxchg has full barrier semantics
    
    Unrelated reads/writes should not pass the xchg.
    
    Provide cmpxchg_local for parity with arm64, although it appears to be 
unused.
    It also helps make the reason for the separation of __cmpxchg_mb more
    apparent.
    
    With this our cmpxchg is in sync with Linux v3.14-rc7.
    
    Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
    Acked-by: Julien Grall <julien.grall@xxxxxxxxxx>
    Acked-by: Tim Deegan <tim@xxxxxxx>
---
 xen/include/asm-arm/arm32/system.h |   26 +++++++++++++++++++++++---
 1 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/xen/include/asm-arm/arm32/system.h 
b/xen/include/asm-arm/arm32/system.h
index 9f233fe..dfaa3b6 100644
--- a/xen/include/asm-arm/arm32/system.h
+++ b/xen/include/asm-arm/arm32/system.h
@@ -113,9 +113,29 @@ static always_inline unsigned long __cmpxchg(
     return oldval;
 }
 
-#define cmpxchg(ptr,o,n)                                                \
-    ((__typeof__(*(ptr)))__cmpxchg((ptr),(unsigned long)(o),            \
-                                   (unsigned long)(n),sizeof(*(ptr))))
+static inline unsigned long __cmpxchg_mb(volatile void *ptr, unsigned long old,
+                                        unsigned long new, int size)
+{
+       unsigned long ret;
+
+       smp_mb();
+       ret = __cmpxchg(ptr, old, new, size);
+       smp_mb();
+
+       return ret;
+}
+
+#define cmpxchg(ptr,o,n)                                               \
+       ((__typeof__(*(ptr)))__cmpxchg_mb((ptr),                        \
+                                         (unsigned long)(o),           \
+                                         (unsigned long)(n),           \
+                                         sizeof(*(ptr))))
+
+#define cmpxchg_local(ptr,o,n)                                         \
+       ((__typeof__(*(ptr)))__cmpxchg((ptr),                           \
+                                      (unsigned long)(o),              \
+                                      (unsigned long)(n),              \
+                                      sizeof(*(ptr))))
 
 #define local_irq_disable() asm volatile ( "cpsid i @ local_irq_disable\n" : : 
: "cc" )
 #define local_irq_enable()  asm volatile ( "cpsie i @ local_irq_enable\n" : : 
: "cc" )
--
generated by git-patchbot for /home/xen/git/xen.git#master

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