From: "Christian König" <ckoenig.leichtzumerken@gmail.com>
To: Daniel Vetter <daniel@ffwll.ch>
Cc: dri-devel@lists.freedesktop.org, chris@chris-wilson.co.uk,
daniel.vetter@ffwll.ch, sumit.semwal@linaro.org,
linux-media@vger.kernel.org, linaro-mm-sig@lists.linaro.org
Subject: Re: [PATCH 07/10] dma-buf/resv: add new fences container implementation
Date: Thu, 22 Aug 2019 10:23:29 +0200 [thread overview]
Message-ID: <c1ff88ef-0e49-fd7a-6317-de432a04ddf2@gmail.com> (raw)
In-Reply-To: <20190821160454.GN11147@phenom.ffwll.local>
Am 21.08.19 um 18:04 schrieb Daniel Vetter:
> On Wed, Aug 21, 2019 at 02:31:44PM +0200, Christian König wrote:
>> [SNIP]
>> + /* Try to drop the last reference */
>> + if (!dma_fence_array_recycle(staged))
> Without an rcu barrier here you're not syncing to new clients at all.
> I don't think this works, and I expect that once you've readded all the
> barriers and retry loops we're back to seqlocks.
The key difference is that RCU users now use dma_fence_get_rcu_safe() to
grab a reference to the current set of fences.
In other words the whole array is reference counted and RCU protected
instead of each individual entry in the array.
This way you don't need the sequence count any more because you grab a
reference to all of them at once and then can be sure that they don't
change.
Regards,
Christian.
> -Daniel
next prev parent reply other threads:[~2019-08-22 8:23 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-21 12:31 [RFC] replacing dma_resv API Christian König
2019-08-21 12:31 ` [PATCH 01/10] dma-buf: make to_dma_fence_array NULL safe Christian König
2019-08-21 12:31 ` [PATCH 02/10] dma-buf: add dma_fence_array_alloc/free Christian König
2019-08-21 12:31 ` [PATCH 03/10] dma-buf: add dma_fence_array_recycle Christian König
2019-08-21 16:24 ` Chris Wilson
2019-08-22 8:38 ` Christian König
2019-08-21 12:31 ` [PATCH 04/10] dma-buf: add dma_fence_array_for_each Christian König
2019-08-21 12:31 ` [PATCH 05/10] dma-buf/resv: add dma_resv_prune_fences Christian König
2019-08-21 14:55 ` Chris Wilson
2019-08-21 14:56 ` Chris Wilson
2019-08-21 12:31 ` [PATCH 06/10] dma-buf/resv: stop pruning shared fences when exclusive is added Christian König
2019-08-21 12:31 ` [PATCH 07/10] dma-buf/resv: add new fences container implementation Christian König
2019-08-21 16:04 ` Daniel Vetter
2019-08-22 8:23 ` Christian König [this message]
2019-08-22 13:02 ` Daniel Vetter
2019-08-22 13:53 ` Koenig, Christian
2019-08-21 12:31 ` [PATCH 08/10] dma-buf/resv: replace shared fence with new fences container Christian König
2019-08-21 15:24 ` Chris Wilson
2019-08-21 17:35 ` Chris Wilson
2019-08-22 8:37 ` Christian König
2019-08-22 9:16 ` Christian König
2019-08-21 16:21 ` Chris Wilson
2019-08-24 13:22 ` Chris Wilson
2019-08-21 12:31 ` [PATCH 09/10] dma-buf/resv: replace exclusive " Christian König
2019-08-21 12:31 ` [PATCH 10/10] dma-buf/resv: add other operations Christian König
2019-08-22 12:28 ` Ville Syrjälä
2019-08-21 16:13 ` [RFC] replacing dma_resv API Daniel Vetter
2019-08-21 20:05 ` Daniel Vetter
2019-08-22 9:27 ` Christian König
2019-08-21 20:11 ` Chris Wilson
2019-08-21 20:22 ` Daniel Vetter
2019-08-22 9:14 ` Christian König
2019-08-22 10:00 ` Daniel Vetter
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=c1ff88ef-0e49-fd7a-6317-de432a04ddf2@gmail.com \
--to=ckoenig.leichtzumerken@gmail.com \
--cc=chris@chris-wilson.co.uk \
--cc=christian.koenig@amd.com \
--cc=daniel.vetter@ffwll.ch \
--cc=daniel@ffwll.ch \
--cc=dri-devel@lists.freedesktop.org \
--cc=linaro-mm-sig@lists.linaro.org \
--cc=linux-media@vger.kernel.org \
--cc=sumit.semwal@linaro.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox