linux-kernel - RE: [PATCH v14 12/12] dmaengine: imx-sdma: add terminated list for freed descriptor in worker

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Message-ID: <VE1PR04MB663877142BA90AADDF9B3AB3894F9@VE1PR04MB6638.eurprd04.prod.outlook.com>
Date:   Tue, 13 Apr 2021 05:05:20 +0000
From:   Robin Gong <yibin.gong@....com>
To:     Vinod Koul <vkoul@...nel.org>
CC:     "mark.rutland@....com" <mark.rutland@....com>,
        "broonie@...nel.org" <broonie@...nel.org>,
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Subject: RE: [PATCH v14 12/12] dmaengine: imx-sdma: add terminated list for
 freed descriptor in worker

On 2021/04/12 17:39,  Vinod Koul <vkoul@...nel.org>  wrote: 
> On 07-04-21, 23:30, Robin Gong wrote:
> > Add terminated list for keeping descriptor so that it could be freed
> > in worker without any potential involving next descriptor raised up
> > before this descriptor freed, because vchan_get_all_descriptors get
> > all descriptors including the last terminated descriptor and the next
> > descriptor, hence, the next descriptor maybe freed unexpectly when
> > it's done in worker without this patch.
> > https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.
> >
> spinics.net%2Flists%2Fdmaengine%2Fmsg23367.html&amp;data=04%7C01%
> 7Cyib
> >
> in.gong%40nxp.com%7Cf255f329c8de459ffbaf08d8fd96d6c5%7C686ea1d3bc
> 2b4c6
> >
> fa92cd99c5c301635%7C0%7C0%7C637538171591949442%7CUnknown%7CT
> WFpbGZsb3d
> >
> 8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3
> D%7C
> >
> 1000&amp;sdata=3YFgzHFDNwRnogvxZpNcwVKOKpk4GHrgScdrbuMKjwE%3D
> &amp;rese
> > rved=0
> 
> Sound like you should implement .device_synchronize() and do the actual
> work there..?
Yes,  I believe no issue here if call dmaengine_terminate_sync() always since
flush_work(&sdmac->terminate_worker) has already been in  .device_synchronize() of
sdma driver. But unfortunately, have to use dmaengine_terminate_all() instead in some
non-atomic case like ALSA.