From: Geert Uytterhoeven <geert@linux-m68k.org>
M68k: Add missing implementation of cmpxchg() (from Andreas Schwab, Roman
Zippel and me)
---
25-akpm/include/asm-m68k/system.h | 36 ++++++++++++++++++++++++++++++++++++
1 files changed, 36 insertions(+)
diff -puN include/asm-m68k/system.h~m68k-411 include/asm-m68k/system.h
--- 25/include/asm-m68k/system.h~m68k-411 Fri Feb 20 15:12:20 2004
+++ 25-akpm/include/asm-m68k/system.h Fri Feb 20 15:12:20 2004
@@ -158,6 +158,42 @@ static inline unsigned long __xchg(unsig
}
#endif
+/*
+ * 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.
+ */
+#ifdef CONFIG_RMW_INSNS
+#define __HAVE_ARCH_CMPXCHG 1
+
+static inline unsigned long __cmpxchg(volatile void *p, unsigned long old,
+ unsigned long new, int size)
+{
+ switch (size) {
+ case 1:
+ __asm__ __volatile__ ("casb %0,%2,%1"
+ : "=d" (old), "=m" (*(char *)p)
+ : "d" (new), "0" (old), "m" (*(char *)p));
+ break;
+ case 2:
+ __asm__ __volatile__ ("casw %0,%2,%1"
+ : "=d" (old), "=m" (*(short *)p)
+ : "d" (new), "0" (old), "m" (*(short *)p));
+ break;
+ case 4:
+ __asm__ __volatile__ ("casl %0,%2,%1"
+ : "=d" (old), "=m" (*(int *)p)
+ : "d" (new), "0" (old), "m" (*(int *)p));
+ break;
+ }
+ return old;
+}
+
+#define cmpxchg(ptr,o,n)\
+ ((__typeof__(*(ptr)))__cmpxchg((ptr),(unsigned long)(o),\
+ (unsigned long)(n),sizeof(*(ptr))))
+#endif
+
#endif /* __KERNEL__ */
#endif /* _M68K_SYSTEM_H */
_