Move the asm-generic/system.h xchg() implementation to asm-generic/cmpxchg.h
Move the asm-generic/system.h xchg() implementation to asm-generic/cmpxchg.h
to simplify disintegration of asm/system.h.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
diff --git a/include/asm-generic/cmpxchg.h b/include/asm-generic/cmpxchg.h
index e0449af..8a36183 100644
--- a/include/asm-generic/cmpxchg.h
+++ b/include/asm-generic/cmpxchg.h
@@ -1,16 +1,87 @@
+/*
+ * 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 <asm-generic/cmpxchg-local.h>
+#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.
@@ -18,7 +89,9 @@
* 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 */