From: "Michel Dänzer" <michel@daenzer.net>
To: "Christian König" <ckoenig.leichtzumerken@gmail.com>
Cc: daniel.vetter@ffwll.ch, dri-devel@lists.freedesktop.org
Subject: Re: [PATCH] dma-buf: fix and rework dma_buf_poll v7
Date: Fri, 23 Jul 2021 10:04:17 +0200 [thread overview]
Message-ID: <97ea61fb-aa20-5220-8304-e71145cc7587@daenzer.net> (raw)
In-Reply-To: <20210720131110.88512-1-christian.koenig@amd.com>
On 2021-07-20 3:11 p.m., Christian König wrote:
> Daniel pointed me towards this function and there are multiple obvious problems
> in the implementation.
>
> First of all the retry loop is not working as intended. In general the retry
> makes only sense if you grab the reference first and then check the sequence
> values.
>
> Then we should always also wait for the exclusive fence.
>
> It's also good practice to keep the reference around when installing callbacks
> to fences you don't own.
>
> And last the whole implementation was unnecessary complex and rather hard to
> understand which could lead to probably unexpected behavior of the IOCTL.
>
> Fix all this by reworking the implementation from scratch. Dropping the
> whole RCU approach and taking the lock instead.
>
> Only mildly tested and needs a thoughtful review of the code.
>
> v2: fix the reference counting as well
> v3: keep the excl fence handling as is for stable
> v4: back to testing all fences, drop RCU
> v5: handle in and out separately
> v6: add missing clear of events
> v7: change coding style as suggested by Michel, drop unused variables
>
> Signed-off-by: Christian König <christian.koenig@amd.com>
> CC: stable@vger.kernel.org
Working fine with https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1880
Tested-by: Michel Dänzer <mdaenzer@redhat.com>
--
Earthling Michel Dänzer | https://redhat.com
Libre software enthusiast | Mesa and X developer
next prev parent reply other threads:[~2021-07-23 8:04 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-20 13:11 [PATCH] dma-buf: fix and rework dma_buf_poll v7 Christian König
2021-07-23 8:04 ` Michel Dänzer [this message]
2021-09-22 11:08 ` Christian König
2021-09-30 9:00 ` Daniel Vetter
2021-09-30 9:48 ` Christian König
2021-09-30 10:26 ` Daniel Vetter
2021-09-30 11:32 ` Christian König
2021-09-30 14:13 ` Daniel Vetter
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