Re: [PATCH 1/3] 2.6.14-rc2-mm1: fixes for overflow msec_to_jiffies()

Willy Tarreau
2005-09-29T19:47:20Z

Thanks Andrew,

I'm very sorry because I have verified the code with gcc-2.95.3,
gcc-3.3.6 and gcc-3.4.4 on x86 and alpha to ensure that everything
went smooth on archs where sizeof(long) > sizeof(int). But I've
tested all the combinations in user-space for obvious ease of
validation. I believe I forgot to use -Wall. What architecture
gave you this, and with which compiler please ? I'm willing to
fix this as soon as I can understand the root of the problem.

Regards,
Willy

On Thu, Sep 29, 2005 at 02:43:12AM -0700, Andrew Morton wrote:
> Willy Tarreau <willy@w.ods.org> wrote:
> >
> > +#if HZ <= MSEC_PER_SEC && !(MSEC_PER_SEC % HZ)
> > +# define MAX_MSEC_OFFSET \
> > + (ULONG_MAX - (MSEC_PER_SEC / HZ) + 1)
>
> That generates numbers which don't fit into unsigned ints, yielding vast
> numbers of
>
> include/linux/jiffies.h: In function `msecs_to_jiffies':
> include/linux/jiffies.h:310: warning: comparison is always false due to limited range of data type
> include/linux/jiffies.h: In function `usecs_to_jiffies':
> include/linux/jiffies.h:323: warning: comparison is always false due to limited range of data type
>