Re: [PATCH 01/15] dmaengine: at_hdmac: fix device leak on of_dma_xlate()

Andy Shevchenko
2025-11-17T17:08:57Z

On Mon, Nov 17, 2025 at 05:12:43PM +0100, Johan Hovold wrote:
> Make sure to drop the reference taken when looking up the DMA platform
> device during of_dma_xlate() when releasing channel resources.
>
> Note that commit 3832b78b3ec2 ("dmaengine: at_hdmac: add missing
> put_device() call in at_dma_xlate()") fixed the leak in a couple of
> error paths but the reference is still leaking on successful allocation.

...

> - kfree(chan->private);
> - chan->private = NULL;
> + atslave = chan->private;
> + if (atslave) {
> + put_device(atslave->dma_dev);
> + kfree(atslave);
> + chan->private = NULL;
> + }

It can also be

atslave = chan->private;
if (atslave)
put_device(atslave->dma_dev);
kfree(chan->private);
chan->private = NULL;

which makes patch shorter.

In any case I'm wondering if the asynchronous nature of put_device() can
collide with chan->private = NULL assignment. I think as long as it's not
used inside ->release() of the device, we are fine.

--
With Best Regards,
Andy Shevchenko