lkml.org 
[lkml]   [2004]   [Nov]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH] Remove pointless <0 comparison for unsigned variable in fs/fcntl.c
    On Tue, 23 Nov 2004, Timur Tabi wrote:

    > Linus Torvalds wrote:
    >
    > > which might warn on an architecture where "pid_t" is just sixteen bits wide.
    > > Does that make the code wrong? Hell no.
    >
    > Wouldn't something like "sizeof(pid_t) > 2" be a better test? It certainly
    > would be a lot easier to understand than comparing with 0xffff.
    >
    That was not the point of the example Linus gave.
    The example Linus gave was a function taking a pid_t argument and then
    comparing the value of the argument passed against 0xffff - the /value/ of
    the pid_t argument passed, not the size of the datatype.

    int fn(pid_t a)
    {
    if (a > 0xffff)
    ...
    }

    if pid_t is 16 bit, then the value can never be greater than 0xffff but,
    if pid_t is greater than 16 bit, say 32 bit, then the argument "a" could
    very well contain a value greater than 0xffff and then the comparison
    makes perfect sense. So, while you'd get a warning on architectures where
    pid_t is 16bit or less you won't get a warning when pid_t is greater than
    16 bit. "fixing" that warning would clearly be wrong, no argument about
    that.


    --
    Jesper Juhl

    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2005-03-22 14:08    [W:0.024 / U:29.992 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site