Re: [PATCH v3 1/2] x86_64,signal: Fix SS handling for signals delivered to 64-bit programs

Denys Vlasenko
2015-03-20T11:43:39Z

On Thu, Mar 19, 2015 at 8:35 AM, Cyrill Gorcunov <gorcunov@gmail.com> wrote:
> On Wed, Mar 18, 2015 at 03:03:27PM -0700, Andy Lutomirski wrote:
>> I don't have a great idea for how to work around this, unfortunately.
>> Ideally we'd increment some kind of version counter or use an
>> extension mechanism rather than shoving ss into a field that used to
>> be padding.
>
> fwiw currently we're passing zero in this __pad0 (replying to your
> previous email, so we can workaround in the kernel assuming zero
> as a special case, not that good but better than nothing).

Special-casing zero sounds not that bad to me.
It can be removed after a few years - just don't forget
to document it in a good comment: why we have special
case? What software required it?
In which version of that software the need to have this hack
was eliminated?