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-rw-r--r--include/linux/kernel.h45
1 files changed, 24 insertions, 21 deletions
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index 2c13f747ac2e..05ce782d53ab 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -200,28 +200,31 @@ extern int _cond_resched(void);
#define might_sleep_if(cond) do { if (cond) might_sleep(); } while (0)
-/*
- * abs() handles unsigned and signed longs, ints, shorts and chars. For all
- * input types abs() returns a signed long.
- * abs() should not be used for 64-bit types (s64, u64, long long) - use abs64()
- * for those.
+/**
+ * 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).
+ *
+ * Return: an absolute value of x. If x is 64-bit, macro's return type is s64,
+ * otherwise it is signed long.
*/
-#define abs(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 abs64(x) ({ \
- s64 __x = (x); \
- (__x < 0) ? -__x : __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; \
+ }))
+
+/* Deprecated, use abs instead. */
+#define abs64(x) abs((s64)(x))
/**
* reciprocal_scale - "scale" a value into range [0, ep_ro)