Re: [PATCH v3] kcmp: Support selection of SYS_kcmp without CHECKPOINT_RESTORE

[Michel Dänzer]

On 2021-02-12 1:57 p.m., Emil Velikov wrote:
> On Fri, 5 Feb 2021 at 22:01, Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> wrote:
> > Userspace has discovered the functionality offered by SYS_kcmp and has
> > started to depend upon it. In particular, Mesa uses SYS_kcmp for
> > os_same_file_description() in order to identify when two fd (e.g. device
> > or dmabuf)
>
> As you rightfully point out, SYS_kcmp is a bit of a two edged sword.
> While you mention the CONFIG issue, there is also a portability aspect
> (mesa runs on more than just linux) and as well as sandbox filtering
> of the extra syscall.
>
> Last time I looked, the latter was still an issue and mesa was using
> SYS_kcmp to compare device node fds.
> A far shorter and more portable solution is possible, so let me
> prepare a Mesa patch.

Make sure to read my comments on 
https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6881 first. :)


--
Earthling Michel Dänzer               |               https://redhat.com
Libre software enthusiast             |             Mesa and X developer