Merge branch 'akpm' (Andrew's patch-bomb)

[linux-2.6-block.git] / include / asm-generic / cmpxchg.h

diff --git a/include/asm-generic/cmpxchg.h b/include/asm-generic/cmpxchg.h
index 213ac6e8fe392b536480898e626ad3ff523a1e5d..8a361834dc25887e658107a3bf5dbf5f8142752d 100644 (file)
--- a/include/asm-generic/cmpxchg.h
+++ b/include/asm-generic/cmpxchg.h
@@ -1,22 +1,97 @@
+/*
+ * Generic UP xchg and cmpxchg using interrupt disablement.  Does not
+ * support SMP.
+ */
+
 #ifndef __ASM_GENERIC_CMPXCHG_H
 #define __ASM_GENERIC_CMPXCHG_H
 
-/*
- * Generic cmpxchg
- *
- * Uses the local cmpxchg. Does not support SMP.
- */
 #ifdef CONFIG_SMP
 #error "Cannot use generic cmpxchg on SMP"
 #endif
 
+#include <linux/irqflags.h>
+
+#ifndef xchg
+
+/*
+ * This function doesn't exist, so you'll get a linker error if
+ * something tries to do an invalidly-sized xchg().
+ */
+extern void __xchg_called_with_bad_pointer(void);
+
+static inline
+unsigned long __xchg(unsigned long x, volatile void *ptr, int size)
+{
+       unsigned long ret, flags;
+
+       switch (size) {
+       case 1:
+#ifdef __xchg_u8
+               return __xchg_u8(x, ptr);
+#else
+               local_irq_save(flags);
+               ret = *(volatile u8 *)ptr;
+               *(volatile u8 *)ptr = x;
+               local_irq_restore(flags);
+               return ret;
+#endif /* __xchg_u8 */
+
+       case 2:
+#ifdef __xchg_u16
+               return __xchg_u16(x, ptr);
+#else
+               local_irq_save(flags);
+               ret = *(volatile u16 *)ptr;
+               *(volatile u16 *)ptr = x;
+               local_irq_restore(flags);
+               return ret;
+#endif /* __xchg_u16 */
+
+       case 4:
+#ifdef __xchg_u32
+               return __xchg_u32(x, ptr);
+#else
+               local_irq_save(flags);
+               ret = *(volatile u32 *)ptr;
+               *(volatile u32 *)ptr = x;
+               local_irq_restore(flags);
+               return ret;
+#endif /* __xchg_u32 */
+
+#ifdef CONFIG_64BIT
+       case 8:
+#ifdef __xchg_u64
+               return __xchg_u64(x, ptr);
+#else
+               local_irq_save(flags);
+               ret = *(volatile u64 *)ptr;
+               *(volatile u64 *)ptr = x;
+               local_irq_restore(flags);
+               return ret;
+#endif /* __xchg_u64 */
+#endif /* CONFIG_64BIT */
+
+       default:
+               __xchg_called_with_bad_pointer();
+               return x;
+       }
+}
+
+#define xchg(ptr, x) \
+       ((__typeof__(*(ptr))) __xchg((unsigned long)(x), (ptr), sizeof(*(ptr))))
+
+#endif /* xchg */
+
 /*
  * Atomic compare and exchange.
  *
  * Do not define __HAVE_ARCH_CMPXCHG because we want to use it to check whether
  * a cmpxchg primitive faster than repeated local irq save/restore exists.
  */
+#include <asm-generic/cmpxchg-local.h>
+
 #define cmpxchg(ptr, o, n)     cmpxchg_local((ptr), (o), (n))
 #define cmpxchg64(ptr, o, n)   cmpxchg64_local((ptr), (o), (n))
 
-#endif
+#endif /* __ASM_GENERIC_CMPXCHG_H */