From: Simon Ser <contact@emersion.fr>
To: Emil Velikov <emil.l.velikov@gmail.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>,
Will Drewry <wad@chromium.org>, Kees Cook <keescook@chromium.org>,
Daniel Vetter <daniel.vetter@ffwll.ch>,
Intel Graphics Development <intel-gfx@lists.freedesktop.org>,
Rasmus Villemoes <linux@rasmusvillemoes.dk>,
"Linux-Kernel@Vger. Kernel. Org" <linux-kernel@vger.kernel.org>,
ML dri-devel <dri-devel@lists.freedesktop.org>,
Andy Lutomirski <luto@amacapital.net>,
Cyrill Gorcunov <gorcunov@gmail.com>,
"# 3.13+" <stable@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH v3] kcmp: Support selection of SYS_kcmp without CHECKPOINT_RESTORE
Date: Fri, 12 Feb 2021 13:14:19 +0000 [thread overview]
Message-ID: <pIyZ-Jj7O2MYk1vKeyghnFmiFWk_5ZWm-Ze1gUqdDaXzImOVjVdjPh2uyHa-sxOPovRk1ApSKk_5zKBvOrzoSwXeXUu0LbZ75Q1D3gIK2Kk=@emersion.fr> (raw)
In-Reply-To: <CACvgo52u1ASWXOuWuDwoXvbZhoq+RHn_GTxD5y9k+kO_dzmT7w@mail.gmail.com>
On Friday, February 12th, 2021 at 1:57 PM, Emil Velikov <emil.l.velikov@gmail.com> wrote:
> On Fri, 5 Feb 2021 at 22:01, Chris Wilson <chris@chris-wilson.co.uk> 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.
Comparing two DMA-BUFs can be done with their inode number, I think.
Comparing two device FDs is more subtle, because of GEM handle
ref'counting. You sometimes really want to check whether two FDs are
backed by the same file *description*. See [1] for details.
[1]: https://gitlab.freedesktop.org/mesa/drm/-/merge_requests/110
WARNING: multiple messages have this Message-ID (diff)
From: Simon Ser <contact@emersion.fr>
To: Emil Velikov <emil.l.velikov@gmail.com>
Cc: Will Drewry <wad@chromium.org>, Kees Cook <keescook@chromium.org>,
Daniel Vetter <daniel.vetter@ffwll.ch>,
Intel Graphics Development <intel-gfx@lists.freedesktop.org>,
Rasmus Villemoes <linux@rasmusvillemoes.dk>,
"Linux-Kernel@Vger. Kernel. Org" <linux-kernel@vger.kernel.org>,
ML dri-devel <dri-devel@lists.freedesktop.org>,
Chris Wilson <chris@chris-wilson.co.uk>,
Cyrill Gorcunov <gorcunov@gmail.com>,
"# 3.13+" <stable@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Andy Lutomirski <luto@amacapital.net>
Subject: Re: [PATCH v3] kcmp: Support selection of SYS_kcmp without CHECKPOINT_RESTORE
Date: Fri, 12 Feb 2021 13:14:19 +0000 [thread overview]
Message-ID: <pIyZ-Jj7O2MYk1vKeyghnFmiFWk_5ZWm-Ze1gUqdDaXzImOVjVdjPh2uyHa-sxOPovRk1ApSKk_5zKBvOrzoSwXeXUu0LbZ75Q1D3gIK2Kk=@emersion.fr> (raw)
In-Reply-To: <CACvgo52u1ASWXOuWuDwoXvbZhoq+RHn_GTxD5y9k+kO_dzmT7w@mail.gmail.com>
On Friday, February 12th, 2021 at 1:57 PM, Emil Velikov <emil.l.velikov@gmail.com> wrote:
> On Fri, 5 Feb 2021 at 22:01, Chris Wilson <chris@chris-wilson.co.uk> 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.
Comparing two DMA-BUFs can be done with their inode number, I think.
Comparing two device FDs is more subtle, because of GEM handle
ref'counting. You sometimes really want to check whether two FDs are
backed by the same file *description*. See [1] for details.
[1]: https://gitlab.freedesktop.org/mesa/drm/-/merge_requests/110
_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel
WARNING: multiple messages have this Message-ID (diff)
From: Simon Ser <contact@emersion.fr>
To: Emil Velikov <emil.l.velikov@gmail.com>
Cc: Will Drewry <wad@chromium.org>, Kees Cook <keescook@chromium.org>,
Daniel Vetter <daniel.vetter@ffwll.ch>,
Intel Graphics Development <intel-gfx@lists.freedesktop.org>,
Rasmus Villemoes <linux@rasmusvillemoes.dk>,
"Linux-Kernel@Vger. Kernel. Org" <linux-kernel@vger.kernel.org>,
ML dri-devel <dri-devel@lists.freedesktop.org>,
Chris Wilson <chris@chris-wilson.co.uk>,
Cyrill Gorcunov <gorcunov@gmail.com>,
"# 3.13+" <stable@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Andy Lutomirski <luto@amacapital.net>
Subject: Re: [Intel-gfx] [PATCH v3] kcmp: Support selection of SYS_kcmp without CHECKPOINT_RESTORE
Date: Fri, 12 Feb 2021 13:14:19 +0000 [thread overview]
Message-ID: <pIyZ-Jj7O2MYk1vKeyghnFmiFWk_5ZWm-Ze1gUqdDaXzImOVjVdjPh2uyHa-sxOPovRk1ApSKk_5zKBvOrzoSwXeXUu0LbZ75Q1D3gIK2Kk=@emersion.fr> (raw)
In-Reply-To: <CACvgo52u1ASWXOuWuDwoXvbZhoq+RHn_GTxD5y9k+kO_dzmT7w@mail.gmail.com>
On Friday, February 12th, 2021 at 1:57 PM, Emil Velikov <emil.l.velikov@gmail.com> wrote:
> On Fri, 5 Feb 2021 at 22:01, Chris Wilson <chris@chris-wilson.co.uk> 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.
Comparing two DMA-BUFs can be done with their inode number, I think.
Comparing two device FDs is more subtle, because of GEM handle
ref'counting. You sometimes really want to check whether two FDs are
backed by the same file *description*. See [1] for details.
[1]: https://gitlab.freedesktop.org/mesa/drm/-/merge_requests/110
_______________________________________________
Intel-gfx mailing list
Intel-gfx@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/intel-gfx
next prev parent reply other threads:[~2021-02-12 13:17 UTC|newest]
Thread overview: 88+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-05 16:37 [PATCH] kernel: Expose SYS_kcmp by default Chris Wilson
2021-02-05 16:37 ` [Intel-gfx] " Chris Wilson
2021-02-05 16:37 ` Chris Wilson
2021-02-05 17:02 ` Lucas Stach
2021-02-05 17:02 ` [Intel-gfx] " Lucas Stach
2021-02-05 17:02 ` Lucas Stach
2021-02-05 18:37 ` Kees Cook
2021-02-05 18:37 ` [Intel-gfx] " Kees Cook
2021-02-05 18:37 ` Kees Cook
2021-02-05 20:53 ` Daniel Vetter
2021-02-05 20:53 ` [Intel-gfx] " Daniel Vetter
2021-02-05 20:53 ` Daniel Vetter
2021-02-08 11:49 ` Michel Dänzer
2021-02-08 11:49 ` [Intel-gfx] " Michel Dänzer
2021-02-08 11:49 ` Michel Dänzer
2021-02-08 13:11 ` Michel Dänzer
2021-02-08 13:11 ` [Intel-gfx] " Michel Dänzer
2021-02-08 13:11 ` Michel Dänzer
2021-02-08 13:34 ` Daniel Vetter
2021-02-08 13:34 ` [Intel-gfx] " Daniel Vetter
2021-02-08 13:34 ` Daniel Vetter
2021-02-08 13:49 ` Michel Dänzer
2021-02-08 13:49 ` [Intel-gfx] " Michel Dänzer
2021-02-08 13:49 ` Michel Dänzer
2021-02-05 19:25 ` kernel test robot
2021-02-05 19:25 ` kernel test robot
2021-02-05 19:25 ` [Intel-gfx] " kernel test robot
2021-02-05 19:25 ` kernel test robot
2021-02-05 19:46 ` kernel test robot
2021-02-05 19:46 ` kernel test robot
2021-02-05 19:46 ` [Intel-gfx] " kernel test robot
2021-02-05 19:46 ` kernel test robot
2021-02-05 21:06 ` [PATCH v2] " Chris Wilson
2021-02-05 21:06 ` [Intel-gfx] " Chris Wilson
2021-02-05 21:06 ` Chris Wilson
2021-02-05 21:16 ` Chris Wilson
2021-02-05 21:16 ` [Intel-gfx] " Chris Wilson
2021-02-05 21:16 ` Chris Wilson
2021-02-05 21:20 ` Kees Cook
2021-02-05 21:20 ` [Intel-gfx] " Kees Cook
2021-02-05 21:20 ` Kees Cook
2021-02-05 21:28 ` Chris Wilson
2021-02-05 21:28 ` [Intel-gfx] " Chris Wilson
2021-02-05 21:28 ` Chris Wilson
2021-02-05 21:48 ` Daniel Vetter
2021-02-05 21:48 ` [Intel-gfx] " Daniel Vetter
2021-02-05 21:48 ` Daniel Vetter
2021-02-05 21:47 ` Rasmus Villemoes
2021-02-05 21:47 ` [Intel-gfx] " Rasmus Villemoes
2021-02-05 21:47 ` Rasmus Villemoes
2021-02-05 22:00 ` [PATCH v3] kcmp: Support selection of SYS_kcmp without CHECKPOINT_RESTORE Chris Wilson
2021-02-05 22:00 ` [Intel-gfx] " Chris Wilson
2021-02-05 22:00 ` Chris Wilson
2021-02-06 12:47 ` Cyrill Gorcunov
2021-02-06 12:47 ` [Intel-gfx] " Cyrill Gorcunov
2021-02-06 12:47 ` Cyrill Gorcunov
2021-02-08 22:12 ` Kees Cook
2021-02-08 22:12 ` [Intel-gfx] " Kees Cook
2021-02-08 22:12 ` Kees Cook
2021-02-16 9:02 ` Daniel Vetter
2021-02-16 9:02 ` [Intel-gfx] " Daniel Vetter
2021-02-16 9:02 ` Daniel Vetter
2021-02-12 12:57 ` Emil Velikov
2021-02-12 12:57 ` [Intel-gfx] " Emil Velikov
2021-02-12 12:57 ` Emil Velikov
2021-02-12 13:14 ` Simon Ser [this message]
2021-02-12 13:14 ` [Intel-gfx] " Simon Ser
2021-02-12 13:14 ` Simon Ser
2021-02-12 14:07 ` Emil Velikov
2021-02-12 14:07 ` [Intel-gfx] " Emil Velikov
2021-02-12 14:07 ` Emil Velikov
2021-02-12 14:01 ` Michel Dänzer
2021-02-12 14:01 ` [Intel-gfx] " Michel Dänzer
2021-02-12 14:01 ` Michel Dänzer
2021-02-12 14:09 ` Emil Velikov
2021-02-12 14:09 ` [Intel-gfx] " Emil Velikov
2021-02-12 14:09 ` Emil Velikov
2021-02-15 8:56 ` Thomas Zimmermann
2021-02-15 8:56 ` [Intel-gfx] " Thomas Zimmermann
2021-02-15 8:56 ` Thomas Zimmermann
2021-02-06 2:01 ` [Intel-gfx] ✓ Fi.CI.BAT: success for kernel: Expose SYS_kcmp by default (rev3) Patchwork
2021-02-06 14:21 ` [Intel-gfx] ✓ Fi.CI.IGT: " Patchwork
2021-02-13 17:40 ` [PATCH] kernel: Expose SYS_kcmp by default Pavel Machek
2021-02-13 17:40 ` [Intel-gfx] " Pavel Machek
2021-02-13 17:40 ` Pavel Machek
2021-02-15 10:23 ` Lucas Stach
2021-02-15 10:23 ` [Intel-gfx] " Lucas Stach
2021-02-15 10:23 ` Lucas Stach
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