dmaengine: switchtec-dma: fix resource leak in alloc_chan_resources

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")
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Link: https://lore.kernel.org/dmaengine/20260707165555.350951F000E9@smtp.kernel.org/T/#u
Link: https://patch.msgid.link/20260902062153.31048-3-logang@deltatee.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

0 files changed, 0 insertions, 0 deletions