Re: [PATCH v2 02/11] dmaengine: switchtec-dma: fix resource leak in alloc_chan_resources

[sashiko-bot@kernel.org]

> switchtec_dma_alloc_chan_resources() returns directly on any later
> failure, without ever freeing the descriptor rings and coherent DMA
> memory it just allocated. The dmaengine core does not call
> device_free_chan_resources() when device_alloc_chan_resources() fails,
> so the driver has to unwind its own partial state.
> 
> The device-removed check also runs after ring_active and
> comp_ring_active have already been set true, so a failure there left
> the channel marked active despite alloc_chan_resources() reporting
> failure.
> 
> Add an error-unwind path that disables the channel and frees the
> descriptor rings on every failure after allocation. ring_active and
> comp_ring_active are cleared under the same locks
> switchtec_dma_free_chan_resources() already uses, since the completion
> tasklet checks comp_ring_active under complete_lock before touching
> the completion ring, and a stale IRQ can still be in flight when this
> unwind path runs.
> 
> Reported-by: Sashiko <sashiko-bot@kernel.org>
> Link: https://lore.kernel.org/dmaengine/20260707165555.350951F000E9@smtp.kernel.org
> Fixes: 30eba9df76ad ("dmaengine: switchtec-dma: Implement hardware initialization and cleanup")
> Signed-off-by: Logan Gunthorpe <logang@deltatee.com>

Sashiko has reviewed this patch and found no issues. It looks great!

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