lkml.org 
[lkml]   [2007]   [Aug]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH] ptrdiff_t is not uintptr_t, damnit
    On Mon, Aug 20, 2007 at 01:29:21AM +0100, Anton Altaparmakov wrote:
    > Hi,
    >
    > On 20 Aug 2007, at 01:19, David Brownell wrote:
    > >On Sunday 19 August 2007, Al Viro wrote:
    > >>is wrong; for one thing, it's a bad C (it's what uintptr_t is for;
    > >>in general
    > >>we are not even promised that ptrdiff_t is large enough to hold a
    > >>pointer,
    > >
    > >ISTR we don't *have* a uintptr_t on all architectures, or that would
    > >be the appropriate thing to use in these 32/64 bit ABI scenarios.
    > >
    > >
    > >>Use unsigned long or uintptr_t instead.
    > >
    > >I suspect you mean "unsigned long long"...
    >
    > No he doesn't. "unsigned long" is guaranteed to be large enough to
    > hold a pointer (at least on Linux anyway).
    >
    > On a 32-bit arch "unsigned long" is 32-bit and pointers are 32-bit.

    ... while unsigned long long is 64bit, which is definitely not what
    one wants. For sparse it's "unsigned long is special".

    FWIW, this patch puts it in linux/types.h as unsigned long. Eventually
    we might want to switch explicit casts to/from unsigned long in such contexts
    to uintptr_t, but for now we can't start complaining about unsigned long -
    too many places are using it. I'll see what can be done to get sane
    assistance from sparse in that kind of work...

    -
    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: 2007-08-20 03:02    [W:0.021 / U:0.376 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site