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-rw-r--r--include/linux/kernel.h36
1 files changed, 18 insertions, 18 deletions
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index 7311c3294e25..f31638c6e873 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -202,26 +202,26 @@ extern int _cond_resched(void);
/**
* abs - return absolute value of an argument
- * @x: the value. If it is unsigned type, it is converted to signed type first
- * (s64, long or int depending on its size).
+ * @x: the value. If it is unsigned type, it is converted to signed type first.
+ * char is treated as if it was signed (regardless of whether it really is)
+ * but the macro's return type is preserved as char.
*
- * Return: an absolute value of x. If x is 64-bit, macro's return type is s64,
- * otherwise it is signed long.
+ * Return: an absolute value of x.
*/
-#define abs(x) __builtin_choose_expr(sizeof(x) == sizeof(s64), ({ \
- s64 __x = (x); \
- (__x < 0) ? -__x : __x; \
- }), ({ \
- long ret; \
- if (sizeof(x) == sizeof(long)) { \
- long __x = (x); \
- ret = (__x < 0) ? -__x : __x; \
- } else { \
- int __x = (x); \
- ret = (__x < 0) ? -__x : __x; \
- } \
- ret; \
- }))
+#define abs(x) __abs_choose_expr(x, long long, \
+ __abs_choose_expr(x, long, \
+ __abs_choose_expr(x, int, \
+ __abs_choose_expr(x, short, \
+ __abs_choose_expr(x, char, \
+ __builtin_choose_expr( \
+ __builtin_types_compatible_p(typeof(x), char), \
+ (char)({ signed char __x = (x); __x<0?-__x:__x; }), \
+ ((void)0)))))))
+
+#define __abs_choose_expr(x, type, other) __builtin_choose_expr( \
+ __builtin_types_compatible_p(typeof(x), signed type) || \
+ __builtin_types_compatible_p(typeof(x), unsigned type), \
+ ({ signed type __x = (x); __x < 0 ? -__x : __x; }), other)
/**
* reciprocal_scale - "scale" a value into range [0, ep_ro)