On 07/22/2013 07:16 PM, Geert Uytterhoeven wrote:
> On Mon, Jul 22, 2013 at 10:07 AM, Chen Gang <gang.chen@xxxxxxxxxxx> wrote:
>> For 'con2fb.framebuffer', it can be '-1' as an invalid value, so it
>> need related type cast for its comparing.
>>
>> The related warning:
>>
>> drivers/video/fbmem.c:1169:3: warning: comparison of unsigned expression < 0 is always false [-Wtype-limits]
>>
>>
>> Signed-off-by: Chen Gang <gang.chen@xxxxxxxxxxx>
>> ---
>> drivers/video/fbmem.c | 2 +-
>> 1 files changed, 1 insertions(+), 1 deletions(-)
>>
>> diff --git a/drivers/video/fbmem.c b/drivers/video/fbmem.c
>> index 36e1fe2..8e8225c 100644
>> --- a/drivers/video/fbmem.c
>> +++ b/drivers/video/fbmem.c
>> @@ -1166,7 +1166,7 @@ static long do_fb_ioctl(struct fb_info *info, unsigned int cmd,
>> return -EFAULT;
>> if (con2fb.console < 1 || con2fb.console > MAX_NR_CONSOLES)
>> return -EINVAL;
>> - if (con2fb.framebuffer < 0 || con2fb.framebuffer >= FB_MAX)
>> + if ((int)con2fb.framebuffer < 0 || con2fb.framebuffer >= FB_MAX)
>> return -EINVAL;
>
> Instead of adding the cast, you can also just remove the check, as it's useless.
> If it's `-1' for invalid, after conversion to unsigned, it will
> trigger the check
> ">= FB_MAX".
>
OH, yes, thanks.
Original implementation is no issue (the compiler will skip the first
checking automatically).
If suitable, I should send patch v2.
Thanks.
> Gr{oetje,eeting}s,
>
> Geert
>
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
>
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
> -- Linus Torvalds
>
>
--
Chen Gang
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