On Mon, 14 Sep 2015 23:46:32 -0400 Tejun Heo <t...@kernel.org> wrote:
> Anyways, let's please get abs() working for all types, one way or the
> other.
That would be by far the best solution, of course.
This seems to work OK:
--- a/include/linux/kernel.h~a
+++ a/include/linux/kernel.h
@@ -207,8 +207,11 @@ extern int _cond_resched(void);
* for those.
*/
#define abs(x) ({ \
- long ret; \
- if (sizeof(x) == sizeof(long)) { \
+ s64 ret; \
+ if (sizeof(x) == sizeof(s64)) { \
+ s64 __x = (x); \
+ ret = (__x < 0) ? -__x : __x; \
+ } else if (sizeof(x) == sizeof(long)) { \
long __x = (x); \
ret = (__x < 0) ? -__x : __x; \
} else { \
Test case:
--- /dev/null
+++ a/lib/xx.c
@@ -0,0 +1,33 @@
+#include <linux/kernel.h>
+
+#define newabs(x) ({ \
+ s64 ret; \
+ if (sizeof(x) == sizeof(s64)) { \
+ s64 __x = (x); \
+ ret = (__x < 0) ? -__x : __x; \
+ } else if (sizeof(x) == sizeof(long)) { \
+ long __x = (x); \
+ ret = (__x < 0) ? -__x : __x; \
+ } else { \
+ int __x = (x); \
+ ret = (__x < 0) ? -__x : __x; \
+ } \
+ ret; \
+ })
+
+#define oldabs(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; \
+ })
+
+int foo(int x)
+{
+ return oldabs(x);
+}
diff -puN lib/Makefile~b lib/Makefile
--- a/lib/Makefile~b
+++ a/lib/Makefile
@@ -13,7 +13,7 @@ lib-y := ctype.o string.o vsprintf.o cmd
sha1.o md5.o irq_regs.o argv_split.o \
proportions.o flex_proportions.o ratelimit.o show_mem.o \
is_single_threaded.o plist.o decompress.o kobject_uevent.o \
- earlycpio.o seq_buf.o nmi_backtrace.o
+ earlycpio.o seq_buf.o nmi_backtrace.o xx.o
obj-$(CONFIG_ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS) += usercopy.o
lib-$(CONFIG_MMU) += ioremap.o
on i386, xx.o's text is 68 bytes with either newabs() or oldabs().
lib/percpu_counter.o's text does get larger with newabs(). That's
because __percpu_counter_compare() is doing abs() on an s64, doh.
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