On Tue, Jul 24, 2012 at 12:55:38PM -0700, Linus Torvalds wrote:
> On Tue, Jul 24, 2012 at 12:43 PM, Josh Boyer <[email protected]> wrote:
> >+ ({ long int __d = (d); \
> > (__builtin_constant_p (__d) \
> >- ? (__d >= __FD_SETSIZE \
> >- ? __fdelt_warn (__d) : (__d / __NFDBITS)) \
> >+ ? (0 <= __d && __d < __FD_SETSIZE
> > \
> >+ ? (__d / __NFDBITS) \
> >+ : __fdelt_warn (__d)) \
> > : __fdelt_chk (__d)); })
>
> Ugh. This depends intimately on gcc doing the whole value range
> propagation thing, and probably generates horrible code when not
> optimizing, but whatever. It's irrelevant.
>
> I vote we get rid of the crap. We'll force-redefine __FD_SETSIZE,
> because that's the one we really care about. And then just use our
> internal names for anything else.
Your vote counts more than mine ;). I just want the problem solved in a
reasonable fasion since it's causing build failures now and the bug was
stalled.
> IOW, just something like this (whitespace-damaged on purpose, because
> it won't even compile as-is: we'll also need to replace the few uses
> of __NFDBITS in the kernel with BITS_PER_LONG).
>
> diff --git a/include/linux/posix_types.h b/include/linux/posix_types.h
> index f04c98cf44f3..8a79a5021dc1 100644
> --- a/include/linux/posix_types.h
> +++ b/include/linux/posix_types.h
> @@ -15,26 +15,14 @@
> */
>
> /*
> - * Those macros may have been defined in <gnu/types.h>. But we always
> - * use the ones here.
> + * This macro may have been defined in <gnu/types.h>. But we always
> + * use the one here.
> */
> -#undef __NFDBITS
> -#define __NFDBITS (8 * sizeof(unsigned long))
> -
> #undef __FD_SETSIZE
> #define __FD_SETSIZE 1024
>
> -#undef __FDSET_LONGS
> -#define __FDSET_LONGS (__FD_SETSIZE/__NFDBITS)
> -
> -#undef __FDELT
> -#define __FDELT(d) ((d) / __NFDBITS)
> -
> -#undef __FDMASK
> -#define __FDMASK(d) (1UL << ((d) % __NFDBITS))
> -
> typedef struct {
> - unsigned long fds_bits [__FDSET_LONGS];
> + unsigned long fds_bits [__FD_SETSIZE / (8*sizeof(long))];
> } __kernel_fd_set;
>
> /* Type of a signal handler. */
>
> Hmm?
Seems fine to me. In addition to the s/__NFDBITS/BITS_PER_LONG change,
I'm guessing you'll want the odd FD_ISSET/CLR/ZERO/etc macros in
linux/time.h killed as well?
If you don't get to it before me, I'll try whipping something up either
later this evening or first thing in the morning.
josh
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