dmaengine: at_hdmac: Fix concurrency over descriptor

The descriptor was added to the free_list before calling the callback,
which could result in reissuing of the same descriptor and calling of a
single callback for both. Move the decriptor to the free list after the
callback is invoked.

Fixes: dc78baa2b90b ("dmaengine: at_hdmac: new driver for the Atmel AHB DMA Controller")
Reported-by: Peter Rosin <peda@axentia.se>
Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/lkml/13c6c9a2-6db5-c3bf-349b-4c127ad3496a@axentia.se/
Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Link: https://lore.kernel.org/r/20221025090306.297886-1-tudor.ambarus@microchip.com
Link: https://lore.kernel.org/r/20221025090306.297886-9-tudor.ambarus@microchip.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

diff --git a/drivers/dma/at_hdmac.c b/drivers/dma/at_hdmac.c
index f1e6fa6af6c25f5e991561f2ffee426b5600ef00..2012ecc578262fcbf193a3eeb8b161fcfb85d13c 100644 (file)
--- a/drivers/dma/at_hdmac.c
+++ b/drivers/dma/at_hdmac.c
@@ -469,11 +469,8 @@ atc_chain_complete(struct at_dma_chan *atchan, struct at_desc *desc)
                desc->memset_buffer = false;
        }
 
-       /* move children to free_list */
-       list_splice_init(&desc->tx_list, &atchan->free_list);
-       /* move myself to free_list */
-       list_move(&desc->desc_node, &atchan->free_list);
-
+       /* Remove transfer node from the active list. */
+       list_del_init(&desc->desc_node);
        spin_unlock_irqrestore(&atchan->lock, flags);
 
        dma_descriptor_unmap(txd);
@@ -483,6 +480,13 @@ atc_chain_complete(struct at_dma_chan *atchan, struct at_desc *desc)
                dmaengine_desc_get_callback_invoke(txd, NULL);
 
        dma_run_dependencies(txd);
+
+       spin_lock_irqsave(&atchan->lock, flags);
+       /* move children to free_list */
+       list_splice_init(&desc->tx_list, &atchan->free_list);
+       /* add myself to free_list */
+       list_add(&desc->desc_node, &atchan->free_list);
+       spin_unlock_irqrestore(&atchan->lock, flags);
 }
 
 /**