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Subject[patch 09/28] Add cmpxchg_local to blackfin, replace __cmpxchg by generic cmpxchg
Use the new generic cmpxchg_local (disables interrupt). Also use the generic
cmpxchg as fallback if SMP is not set since nobody seems to know why __cmpxchg
has been implemented in assembly in the first place thather than in plain C.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
CC: clameter@sgi.com
CC: michael.frysinger@analog.com
---
include/asm-blackfin/system.h | 59 ++++++++----------------------------------
1 file changed, 12 insertions(+), 47 deletions(-)
Index: linux-2.6-lttng/include/asm-blackfin/system.h
===================================================================
--- linux-2.6-lttng.orig/include/asm-blackfin/system.h 2007-08-07 14:31:52.000000000 -0400
+++ linux-2.6-lttng/include/asm-blackfin/system.h 2007-08-07 14:47:31.000000000 -0400
@@ -176,55 +176,20 @@ static inline unsigned long __xchg(unsig
return tmp;
}

+#include <asm-generic/cmpxchg-local.h>
+
/*
- * Atomic compare and exchange. Compare OLD with MEM, if identical,
- * store NEW in MEM. Return the initial value in MEM. Success is
- * indicated by comparing RETURN with OLD.
+ * cmpxchg_local and cmpxchg64_local are atomic wrt current CPU. Always make
+ * them available.
*/
-static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old,
- unsigned long new, int size)
-{
- unsigned long tmp = 0;
- unsigned long flags = 0;
-
- local_irq_save(flags);
-
- switch (size) {
- case 1:
- __asm__ __volatile__
- ("%0 = b%3 (z);\n\t"
- "CC = %1 == %0;\n\t"
- "IF !CC JUMP 1f;\n\t"
- "b%3 = %2;\n\t"
- "1:\n\t"
- : "=&d" (tmp) : "d" (old), "d" (new), "m" (*__xg(ptr)) : "memory");
- break;
- case 2:
- __asm__ __volatile__
- ("%0 = w%3 (z);\n\t"
- "CC = %1 == %0;\n\t"
- "IF !CC JUMP 1f;\n\t"
- "w%3 = %2;\n\t"
- "1:\n\t"
- : "=&d" (tmp) : "d" (old), "d" (new), "m" (*__xg(ptr)) : "memory");
- break;
- case 4:
- __asm__ __volatile__
- ("%0 = %3;\n\t"
- "CC = %1 == %0;\n\t"
- "IF !CC JUMP 1f;\n\t"
- "%3 = %2;\n\t"
- "1:\n\t"
- : "=&d" (tmp) : "d" (old), "d" (new), "m" (*__xg(ptr)) : "memory");
- break;
- }
- local_irq_restore(flags);
- return tmp;
-}
-
-#define cmpxchg(ptr,o,n)\
- ((__typeof__(*(ptr)))__cmpxchg((ptr),(unsigned long)(o),\
- (unsigned long)(n),sizeof(*(ptr))))
+#define cmpxchg_local(ptr,o,n) \
+ (__typeof__(*(ptr)))__cmpxchg_local_generic((ptr), (unsigned long)(o), \
+ (unsigned long)(n), sizeof(*(ptr)))
+#define cmpxchg64_local(ptr,o,n) __cmpxchg64_local_generic((ptr), (o), (n))
+
+#ifndef CONFIG_SMP
+#include <asm-generic/cmpxchg.h>
+#endif

#define prepare_to_switch() do { } while(0)

--
Mathieu Desnoyers
Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68
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