linux-kernel - Re: [PATCH 1/4 v2] dmaengine: add a tx_free method to struct dma_async_tx

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <e9c3a7c20812101158h3de9c604i1c88bb7c412ccf02@mail.gmail.com>
Date:	Wed, 10 Dec 2008 12:58:09 -0700
From:	"Dan Williams" <dan.j.williams@...el.com>
To:	"Guennadi Liakhovetski" <g.liakhovetski@....de>
Cc:	linux-kernel@...r.kernel.org,
	linux-fbdev-devel@...ts.sourceforge.net, adaplas@...il.com,
	"Sascha Hauer" <s.hauer@...gutronix.de>,
	linux-arm-kernel@...ts.arm.linux.org.uk
Subject: Re: [PATCH 1/4 v2] dmaengine: add a tx_free method to struct dma_async_tx_descriptor

On Wed, Dec 10, 2008 at 3:36 AM, Guennadi Liakhovetski
<g.liakhovetski@....de> wrote:
> From: Guennadi Liakhovetski <lg@...x.de>
>
> Some users reuse DMA transaction descriptors multiple times and need an
> explicit call to release them. An example of such a user is Video4Linux, which
> has to be able to release descriptors on ioctl(VIDIOC_DQBUF).
>
> Signed-off-by: Guennadi Liakhovetski <lg@...x.de>


Hi Guennadi,

Other dmaengine drivers have tasklets that scan the list of completed
descriptors and free the "acked" ones.  This happens in the cleanup
tasklet...
/me looks
...hmm this driver does not have a cleanup routine?  Ideally support
for ioctl(VIDIOC_DQBUF) could be achieved through this mechanism
without needing to increase the size of dma_async_tx_descriptor (which
has cache utilization impacts on other drivers).

--
Dan
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/