Re: [PATCH v5 09/17] dmaengine: sh: rz-dmac: Use virt-dma APIs for channel descriptor processing

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] Active descriptor (`channel->desc`) is leaked in `rz_dmac_free_chan_resources()` if the channel is not explicitly terminated.
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commit 215fec8fbe90c070b8a33e790b492a28153d2d70
Author: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>

dmaengine: sh: rz-dmac: Use virt-dma APIs for channel descriptor processing

This commit refactors the rz-dmac driver to fully utilize virt-dma APIs for
descriptor management. It replaces the internal ld_queue and ld_active lists
with virt-dma equivalents, and introduces channel->desc to track the currently
processing descriptor.

> diff --git a/drivers/dma/sh/rz-dmac.c b/drivers/dma/sh/rz-dmac.c
> index 042f85e58a799..53ee9fe652614 100644
> --- a/drivers/dma/sh/rz-dmac.c
> +++ b/drivers/dma/sh/rz-dmac.c
[ ... ]
> @@ -494,8 +485,6 @@ static void rz_dmac_free_chan_resources(struct dma_chan *chan)
>  	rz_lmdesc_setup(channel, channel->lmdesc.base);
>  
>  	rz_dmac_disable_hw(channel);
> -	list_splice_tail_init(&channel->ld_active, &channel->ld_free);
> -	list_splice_tail_init(&channel->ld_queue, &channel->ld_free);

Does this leak the active descriptor if the channel is freed without being
explicitly terminated?

The original code moved the active descriptors back to ld_free for cleanup.
With the new code using channel->desc for the active transfer, if a client
releases the channel without calling dmaengine_terminate_sync(),
channel->desc could remain non-NULL.

Since channel->desc is detached from all virt-dma lists and the driver's
ld_free list, neither vchan_free_chan_resources() nor the subsequent kfree
loop over ld_free will free it, preventing channel->descs_allocated from
decrementing correctly.

>  
>  	if (channel->mid_rid >= 0) {
>  		clear_bit(channel->mid_rid, dmac->modules);

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Sashiko AI review · https://sashiko.dev/#/patchset/20260512121219.216159-1-claudiu.beznea.uj@bp.renesas.com?part=9