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| author | Guenter Roeck <linux@roeck-us.net> | 2012-09-18 20:42:31 -0700 |
|---|---|---|
| committer | Guenter Roeck <linux@roeck-us.net> | 2012-09-19 06:51:25 -0700 |
| commit | 263a523d18bca306016d75f5c8d5c57c37fe52fb (patch) | |
| tree | 085d8f549b1d133b00363535afe6b9e510dc9718 | |
| parent | 521cf6489269f5b223c24857d99c779e91f42d3e (diff) | |
| download | linux-3.10-263a523d18bca306016d75f5c8d5c57c37fe52fb.tar.gz linux-3.10-263a523d18bca306016d75f5c8d5c57c37fe52fb.tar.bz2 linux-3.10-263a523d18bca306016d75f5c8d5c57c37fe52fb.zip | |
linux/kernel.h: Fix warning seen with W=1 due to change in DIV_ROUND_CLOSEST
After commit b6d86d3d (Fix DIV_ROUND_CLOSEST to support negative dividends),
the following warning is seen if the kernel is compiled with W=1 (-Wextra):
warning: comparison of unsigned expression >= 0 is always true
The warning is due to the test '((typeof(x))-1) >= 0', which is used to detect
if the variable type is unsigned. Research on the web suggests that the warning
disappears if '>' instead of '>=' is used for the comparison.
Tests after changing the macro along that line show that the warning is gone,
and that the result is still correct:
i=-4: DIV_ROUND_CLOSEST(i, 2)=-2
i=-3: DIV_ROUND_CLOSEST(i, 2)=-2
i=-2: DIV_ROUND_CLOSEST(i, 2)=-1
i=-1: DIV_ROUND_CLOSEST(i, 2)=-1
i=0: DIV_ROUND_CLOSEST(i, 2)=0
i=1: DIV_ROUND_CLOSEST(i, 2)=1
i=2: DIV_ROUND_CLOSEST(i, 2)=1
i=3: DIV_ROUND_CLOSEST(i, 2)=2
i=4: DIV_ROUND_CLOSEST(i, 2)=2
Code size is the same as before.
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Tested-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Acked-by: Jean Delvare <khali@linux-fr.org>
| -rw-r--r-- | include/linux/kernel.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/include/linux/kernel.h b/include/linux/kernel.h index 594b419b7d2..2451f1f7a1d 100644 --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -91,7 +91,7 @@ { \ typeof(x) __x = x; \ typeof(divisor) __d = divisor; \ - (((typeof(x))-1) >= 0 || (__x) >= 0) ? \ + (((typeof(x))-1) > 0 || (__x) > 0) ? \ (((__x) + ((__d) / 2)) / (__d)) : \ (((__x) - ((__d) / 2)) / (__d)); \ } \ |