Commit 263a523d authored by Guenter Roeck's avatar Guenter Roeck

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: default avatarGuenter Roeck <linux@roeck-us.net>
Tested-by: default avatarMauro Carvalho Chehab <mchehab@redhat.com>
Acked-by: default avatarJean Delvare <khali@linux-fr.org>
parent 521cf648
...@@ -91,7 +91,7 @@ ...@@ -91,7 +91,7 @@
{ \ { \
typeof(x) __x = x; \ typeof(x) __x = x; \
typeof(divisor) __d = divisor; \ typeof(divisor) __d = divisor; \
(((typeof(x))-1) >= 0 || (__x) >= 0) ? \ (((typeof(x))-1) > 0 || (__x) > 0) ? \
(((__x) + ((__d) / 2)) / (__d)) : \ (((__x) + ((__d) / 2)) / (__d)) : \
(((__x) - ((__d) / 2)) / (__d)); \ (((__x) - ((__d) / 2)) / (__d)); \
} \ } \
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment