Add cmpxchg_local to sparc, move __cmpxchg to system.h

Move cmpxchg and add cmpxchg_local to system.h.
Use the new generic cmpxchg_local (disables interrupt).

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: William Lee Irwin III <wli@holomorphy.com>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 48 insertions, 0 deletions

diff --git a/include/asm-sparc/system.h b/include/asm-sparc/system.h
index 2655d142b22d..45e47c159a6e 100644
--- a/include/asm-sparc/system.h
+++ b/include/asm-sparc/system.h
@@ -225,6 +225,54 @@ static inline unsigned long __xchg(unsigned long x, __volatile__ void * ptr, int
         return x;
 }
 
+/* Emulate cmpxchg() the same way we emulate atomics,
+ * by hashing the object address and indexing into an array
+ * of spinlocks to get a bit of performance...
+ *
+ * See arch/sparc/lib/atomic32.c for implementation.
+ *
+ * Cribbed from <asm-parisc/atomic.h>
+ */
+#define __HAVE_ARCH_CMPXCHG     1
+
+/* bug catcher for when unsupported size is used - won't link */
+extern void __cmpxchg_called_with_bad_pointer(void);
+/* we only need to support cmpxchg of a u32 on sparc */
+extern unsigned long __cmpxchg_u32(volatile u32 *m, u32 old, u32 new_);
+
+/* don't worry...optimizer will get rid of most of this */
+static inline unsigned long
+__cmpxchg(volatile void *ptr, unsigned long old, unsigned long new_, int size)
+{
+        switch (size) {
+        case 4:
+                return __cmpxchg_u32((u32 *)ptr, (u32)old, (u32)new_);
+        default:
+                __cmpxchg_called_with_bad_pointer();
+                break;
+        }
+        return old;
+}
+
+#define cmpxchg(ptr, o, n)                                              \
+({                                                                      \
+        __typeof__(*(ptr)) _o_ = (o);                                   \
+        __typeof__(*(ptr)) _n_ = (n);                                   \
+        (__typeof__(*(ptr))) __cmpxchg((ptr), (unsigned long)_o_,       \
+                        (unsigned long)_n_, sizeof(*(ptr)));            \
+})
+
+#include <asm-generic/cmpxchg-local.h>
+
+/*
+ * cmpxchg_local and cmpxchg64_local are atomic wrt current CPU. Always make
+ * them available.
+ */
+#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))
+
 extern void die_if_kernel(char *str, struct pt_regs *regs) __attribute__ ((noreturn));
 
 #endif /* __KERNEL__ */