Re: [PATCH] Use __kernel_long_t in struct mq_attr

From: H.J. Lu
Date: Thu Dec 26 2013 - 12:59:59 EST

On Thu, Dec 26, 2013 at 9:53 AM, H. Peter Anvin <hpa@xxxxxxxxx> wrote:
> On 12/26/2013 07:54 AM, H.J. Lu wrote:
>> On Wed, Dec 25, 2013 at 08:58:34AM -0800, H.J. Lu wrote:
>>> Both x32 and x86-64 use the same struct mq_attr for system calls. But
>>> x32 long is 32-bit. This patch replaces long with __kernel_long_t in
>>> struct mq_attr.
>> Here is the updated patch which uses __kernel_long_t only if
>> __BITS_PER_LONG == 64.
> That seems wrong in multiple ways... not only does it add more clutter,

It is true for more clutter.

> but it would seem to give the wrong types when __BITS_PER_LONG in
> userspace is 32.

For x32, __BITS_PER_LONG is 64, not 32. If __BITS_PER_LONG
is 32, my patch doesn't change anything. If it works before,
it still works. If it is broken before, it remains broken.

I prefer my first patch, which is less clutter. But I can't guarantee
it is correct for all x3-like ABIs. My second patch has more
clutter, but it has no impact on other ABIs.

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