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From: Daniel Vetter <daniel@ffwll.ch>
To: Daniel Stone <daniel@fooishbar.org>
Cc: linux-rdma <linux-rdma@vger.kernel.org>,
	"Daniel Vetter" <daniel.vetter@ffwll.ch>,
	"Intel Graphics Development" <intel-gfx@lists.freedesktop.org>,
	"DRI Development" <dri-devel@lists.freedesktop.org>,
	"Chris Wilson" <chris@chris-wilson.co.uk>,
	"moderated list:DMA BUFFER SHARING FRAMEWORK"
	<linaro-mm-sig@lists.linaro.org>,
	"Thomas Hellström" <thomas.hellstrom@intel.com>,
	"amd-gfx list" <amd-gfx@lists.freedesktop.org>,
	"Felix Kuehling" <Felix.Kuehling@amd.com>,
	"Daniel Vetter" <daniel.vetter@intel.com>,
	"Mika Kuoppala" <mika.kuoppala@intel.com>,
	"Christian König" <christian.koenig@amd.com>,
	"open list:DMA BUFFER SHARING FRAMEWORK"
	<linux-media@vger.kernel.org>
Subject: Re: [Intel-gfx] [PATCH 01/25] dma-fence: basic lockdep annotations
Date: Thu, 9 Jul 2020 09:52:16 +0200	[thread overview]
Message-ID: <20200709075216.GM3278063@phenom.ffwll.local> (raw)
In-Reply-To: <CAPj87rNXneE+Vry4aSV11=Qv2mbUsFjCLmNzRmx-Oeqj=u9dyw@mail.gmail.com>

On Thu, Jul 09, 2020 at 08:32:41AM +0100, Daniel Stone wrote:
> Hi,
> 
> On Wed, 8 Jul 2020 at 16:13, Daniel Vetter <daniel.vetter@ffwll.ch> wrote:
> > On Wed, Jul 8, 2020 at 4:57 PM Christian König <christian.koenig@amd.com> wrote:
> > > Could we merge this controlled by a separate config option?
> > >
> > > This way we could have the checks upstream without having to fix all the
> > > stuff before we do this?
> >
> > Since it's fully opt-in annotations nothing blows up if we don't merge
> > any annotations. So we could start merging the first 3 patches. After
> > that the fun starts ...
> >
> > My rough idea was that first I'd try to tackle display, thus far
> > there's 2 actual issues in drivers:
> > - amdgpu has some dma_resv_lock in commit_tail, plus a kmalloc. I
> > think those should be fairly easy to fix (I'd try a stab at them even)
> > - vmwgfx has a full on locking inversion with dma_resv_lock in
> > commit_tail, and that one is functional. Not just reading something
> > which we can safely assume to be invariant anyway (like the tmz flag
> > for amdgpu, or whatever it was).
> >
> > I've done a pile more annotations patches for other atomic drivers
> > now, so hopefully that flushes out any remaining offenders here. Since
> > some of the annotations are in helper code worst case we might need a
> > dev->mode_config.broken_atomic_commit flag to disable them. At least
> > for now I have 0 plans to merge any of these while there's known
> > unsolved issues. Maybe if some drivers take forever to get fixed we
> > can then apply some duct-tape for the atomic helper annotation patch.
> > Instead of a flag we can also copypasta the atomic_commit_tail hook,
> > leaving the annotations out and adding a huge warning about that.
> 
> How about an opt-in drm_driver DRIVER_DEADLOCK_HAPPY flag? At first
> this could just disable the annotations and nothing else, but as we
> see the annotations gaining real-world testing and maturity, we could
> eventually make it taint the kernel.

You can do that pretty much per-driver, since the annotations are pretty
much per-driver. No annotations in your code, no lockdep splat. Only if
there's some dma_fence_begin/end_signalling() calls is there even the
chance of a problem.

E.g. this round has the i915 patch dropped and *traraaaa* intel-gfx-ci is
happy (or well at least a lot happier, there's some noise in there that's
probably not from my stuff).

So I guess if amd wants this, we could do an DRM_AMDGPU_MOAR_LOCKDEP
Kconfig or similar. I haven't tested, but I think as long as we don't
merge any of the amdgpu specific patches, there's no splat in amdgpu. So
with that I think that's plenty enough opt-in for each driver. The only
problem is a bit shared helper code like atomic helpers and drm scheduler.
There we might need some opt-out (I don't think merging makes sense when
most of the users are still broken).
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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  reply	other threads:[~2020-07-09  7:52 UTC|newest]

Thread overview: 119+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-07 20:12 [PATCH 00/25] dma-fence annotations, round 3 Daniel Vetter
2020-07-07 20:12 ` [PATCH 01/25] dma-fence: basic lockdep annotations Daniel Vetter
2020-07-08 14:57   ` Christian König
2020-07-08 15:12     ` Daniel Vetter
2020-07-08 15:19       ` Alex Deucher
2020-07-08 15:37         ` Daniel Vetter
2020-07-14 11:09           ` Daniel Vetter
2020-07-09  7:32       ` [Intel-gfx] " Daniel Stone
2020-07-09  7:52         ` Daniel Vetter [this message]
2020-07-13 16:26     ` Daniel Vetter
2020-07-13 16:39       ` Christian König
2020-07-13 20:31         ` Dave Airlie
2020-07-07 20:12 ` [PATCH 02/25] dma-fence: prime " Daniel Vetter
2020-07-09  8:09   ` Daniel Vetter
2020-07-10 12:43     ` Jason Gunthorpe
2020-07-10 12:48       ` Christian König
2020-07-10 12:54         ` Jason Gunthorpe
2020-07-10 13:01           ` Christian König
2020-07-10 13:48             ` Jason Gunthorpe
2020-07-10 14:02               ` Daniel Vetter
2020-07-10 14:23                 ` Jason Gunthorpe
2020-07-10 20:02                   ` Daniel Vetter
2020-07-07 20:12 ` [PATCH 03/25] dma-buf.rst: Document why idenfinite fences are a bad idea Daniel Vetter
2020-07-09  7:36   ` [Intel-gfx] " Daniel Stone
2020-07-09  8:04     ` Daniel Vetter
2020-07-09 12:11       ` Daniel Stone
2020-07-09 12:31         ` Daniel Vetter
2020-07-09 14:28           ` Christian König
2020-07-09 11:53   ` Christian König
2020-07-09 12:33   ` [PATCH 1/2] dma-buf.rst: Document why indefinite " Daniel Vetter
2020-07-09 12:33     ` [PATCH 2/2] drm/virtio: Remove open-coded commit-tail function Daniel Vetter
2020-07-09 12:48       ` Gerd Hoffmann
2020-07-09 14:05       ` Sam Ravnborg
2020-07-14  9:13         ` Daniel Vetter
2020-08-19 12:43       ` Jiri Slaby
2020-08-19 12:47         ` Jiri Slaby
2020-08-19 13:24         ` Gerd Hoffmann
2020-08-20  6:32           ` Jiri Slaby
2020-08-21  7:01             ` Gerd Hoffmann
2020-07-10 12:30     ` [PATCH 1/2] dma-buf.rst: Document why indefinite fences are a bad idea Maarten Lankhorst
2020-07-14 17:46     ` Jason Ekstrand
2020-07-20 11:15     ` [Linaro-mm-sig] " Thomas Hellström (Intel)
2020-07-21  7:41       ` Daniel Vetter
2020-07-21  7:45         ` Christian König
2020-07-21  8:47           ` Thomas Hellström (Intel)
2020-07-21  8:55             ` Christian König
2020-07-21  9:16               ` Daniel Vetter
2020-07-21  9:24                 ` Daniel Vetter
2020-07-21  9:37               ` Thomas Hellström (Intel)
2020-07-21  9:50                 ` Daniel Vetter
2020-07-21 10:47                   ` Thomas Hellström (Intel)
2020-07-21 13:59                     ` Christian König
2020-07-21 17:46                       ` Thomas Hellström (Intel)
2020-07-21 18:18                         ` Daniel Vetter
2020-07-21 21:42                       ` Dave Airlie
2020-07-21 22:45             ` Dave Airlie
2020-07-22  6:45               ` Thomas Hellström (Intel)
2020-07-22  7:11                 ` Daniel Vetter
2020-07-22  8:05                   ` Thomas Hellström (Intel)
2020-07-22  9:45                     ` Daniel Vetter
2020-07-22 10:31                       ` Thomas Hellström (Intel)
2020-07-22 11:39                         ` Daniel Vetter
2020-07-22 12:22                           ` Thomas Hellström (Intel)
2020-07-22 12:41                             ` Daniel Vetter
2020-07-22 13:12                               ` Thomas Hellström (Intel)
2020-07-22 14:07                                 ` Daniel Vetter
2020-07-22 14:23                                   ` Christian König
2020-07-22 14:30                                     ` Thomas Hellström (Intel)
2020-07-22 14:35                                       ` Christian König
2020-07-07 20:12 ` [PATCH 04/25] drm/vkms: Annotate vblank timer Daniel Vetter
2020-07-12 22:27   ` Rodrigo Siqueira
2020-07-14  9:57     ` Melissa Wen
2020-07-14  9:59       ` Daniel Vetter
2020-07-14 14:55         ` Melissa Wen
2020-07-14 15:23           ` Daniel Vetter
2020-07-07 20:12 ` [PATCH 05/25] drm/vblank: Annotate with dma-fence signalling section Daniel Vetter
2020-07-07 20:12 ` [PATCH 06/25] drm/amdgpu: add dma-fence annotations to atomic commit path Daniel Vetter
2020-07-07 20:12 ` [PATCH 07/25] drm/komdea: Annotate dma-fence critical section in " Daniel Vetter
2020-07-08  5:17   ` james qian wang (Arm Technology China)
2020-07-14  8:34     ` Daniel Vetter
2020-07-07 20:12 ` [PATCH 08/25] drm/malidp: " Daniel Vetter
2020-07-15 12:53   ` Liviu Dudau
2020-07-15 13:51     ` Daniel Vetter
2020-07-07 20:12 ` [PATCH 09/25] drm/atmel: Use drm_atomic_helper_commit Daniel Vetter
2020-07-07 20:37   ` Sam Ravnborg
2020-07-07 21:31   ` [PATCH] " Daniel Vetter
2020-07-14  9:55     ` Sam Ravnborg
2020-07-07 20:12 ` [PATCH 10/25] drm/imx: Annotate dma-fence critical section in commit path Daniel Vetter
2020-07-07 20:12 ` [PATCH 11/25] drm/omapdrm: " Daniel Vetter
2020-07-07 20:12 ` [PATCH 12/25] drm/rcar-du: " Daniel Vetter
2020-07-07 23:32   ` Laurent Pinchart
2020-07-14  8:39     ` Daniel Vetter
2020-07-07 20:12 ` [PATCH 13/25] drm/tegra: " Daniel Vetter
2020-07-07 20:12 ` [PATCH 14/25] drm/tidss: " Daniel Vetter
2020-07-08  9:01   ` Jyri Sarha
2020-07-07 20:12 ` [PATCH 15/25] drm/tilcdc: Use standard drm_atomic_helper_commit Daniel Vetter
2020-07-08  9:17   ` Jyri Sarha
2020-07-08  9:27     ` Daniel Vetter
2020-07-08  9:44   ` [PATCH] " Daniel Vetter
2020-07-08 10:21     ` Jyri Sarha
2020-07-08 14:20   ` Daniel Vetter
2020-07-10 11:16     ` Jyri Sarha
2020-07-14  8:32       ` Daniel Vetter
2020-07-07 20:12 ` [PATCH 16/25] drm/atomic-helper: Add dma-fence annotations Daniel Vetter
2020-07-07 20:12 ` [PATCH 17/25] drm/scheduler: use dma-fence annotations in main thread Daniel Vetter
2020-07-07 20:12 ` [PATCH 18/25] drm/amdgpu: use dma-fence annotations in cs_submit() Daniel Vetter
2020-07-07 20:12 ` [PATCH 19/25] drm/amdgpu: s/GFP_KERNEL/GFP_ATOMIC in scheduler code Daniel Vetter
2020-07-14 10:49   ` Daniel Vetter
2020-07-14 11:40     ` Christian König
2020-07-14 14:31       ` Daniel Vetter
2020-07-15  9:17         ` Christian König
2020-07-15 11:53           ` Daniel Vetter
2020-07-07 20:12 ` [PATCH 20/25] drm/amdgpu: DC also loves to allocate stuff where it shouldn't Daniel Vetter
2020-07-14 11:12   ` Daniel Vetter
2020-07-07 20:12 ` [PATCH 21/25] drm/amdgpu/dc: Stop dma_resv_lock inversion in commit_tail Daniel Vetter
2020-07-07 20:12 ` [PATCH 22/25] drm/scheduler: use dma-fence annotations in tdr work Daniel Vetter
2020-07-07 20:12 ` [PATCH 23/25] drm/amdgpu: use dma-fence annotations for gpu reset code Daniel Vetter
2020-07-07 20:12 ` [PATCH 24/25] Revert "drm/amdgpu: add fbdev suspend/resume on gpu reset" Daniel Vetter
2020-07-07 20:12 ` [PATCH 25/25] drm/amdgpu: gpu recovery does full modesets Daniel Vetter

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