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

[Andy Shevchenko]

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