Re: 2.6.17-rc1 core_sys_select incompatible pointer types

From: Keith Owens
Date: Mon Apr 03 2006 - 05:18:39 EST


Andrew Morton (on Mon, 3 Apr 2006 02:09:16 -0700) wrote:
>Mitchell Blank Jr <mitch@xxxxxxxxxx> wrote:
>> I posted a patch to fix this and another problem with the recent select
>> changes a couple days ago.
>>
>> Original version, with description:
>> http://lkml.org/lkml/2006/3/31/308
>> Slightly updated:
>> http://lkml.org/lkml/2006/3/31/316
>>
>> I'm hoping that Andrew picked it up.
>
>Nope. I queued up the below. If anything additional is needed, please
>resend.
>
>
>diff -puN fs/select.c~select-warning-fixes fs/select.c
>--- devel/fs/select.c~select-warning-fixes 2006-04-01 22:27:14.000000000 -0800
>+++ devel-akpm/fs/select.c 2006-04-01 22:28:50.000000000 -0800
>@@ -310,7 +310,7 @@ static int core_sys_select(int n, fd_set
> fd_set __user *exp, s64 *timeout)
> {
> fd_set_bits fds;
>- char *bits;
>+ void *bits;
> int ret, size, max_fdset;
> struct fdtable *fdt;
> /* Allocate small arguments on the stack to save memory and be faster */
>@@ -341,12 +341,12 @@ static int core_sys_select(int n, fd_set
> bits = kmalloc(6 * size, GFP_KERNEL);
> if (!bits)
> goto out_nofds;
>- fds.in = (unsigned long *) bits;
>- fds.out = (unsigned long *) (bits + size);
>- fds.ex = (unsigned long *) (bits + 2*size);
>- fds.res_in = (unsigned long *) (bits + 3*size);
>- fds.res_out = (unsigned long *) (bits + 4*size);
>- fds.res_ex = (unsigned long *) (bits + 5*size);
>+ fds.in = bits;
>+ fds.out = bits + size;
>+ fds.ex = bits + 2*size;
>+ fds.res_in = bits + 3*size;
>+ fds.res_out = bits + 4*size;
>+ fds.res_ex = bits + 5*size;
>
> if ((ret = get_fd_set(n, inp, fds.in)) ||
> (ret = get_fd_set(n, outp, fds.out)) ||

When did arithmetic on void pointers become acceptable? I know that it
is a gcc extension but AFAIK its use is discouraged. Or am I in the
wrong parallel universe again?

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