Commit 03ed9ba3 authored by Tudor Ambarus's avatar Tudor Ambarus Committed by Vinod Koul
Browse files

dmaengine: at_hdmac: Fix concurrency over the active list 



The tasklet (atc_advance_work()) did not held the channel lock when
retrieving the first active descriptor, causing concurrency problems if
issue_pending() was called in between. If issue_pending() was called
exactly after the lock was released in the tasklet (atc_advance_work()),
atc_chain_complete() could complete a descriptor for which the controller
has not yet raised an interrupt.

Fixes: dc78baa2 ("dmaengine: at_hdmac: new driver for the Atmel AHB DMA Controller")
Reported-by: default avatarPeter Rosin <peda@axentia.se>
Signed-off-by: default avatarTudor 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: default avatarNicolas Ferre <nicolas.ferre@microchip.com>
Link: https://lore.kernel.org/r/20221025090306.297886-1-tudor.ambarus@microchip.com
Link: https://lore.kernel.org/r/20221025090306.297886-11-tudor.ambarus@microchip.com


Signed-off-by: default avatarVinod Koul <vkoul@kernel.org>
parent 6ba826cb

drivers/dma/at_hdmac.c

+6 −4
Original line number Diff line number Diff line
@@ -462,8 +462,6 @@ atc_chain_complete(struct at_dma_chan *atchan, struct at_desc *desc) 
	if (!atc_chan_is_cyclic(atchan))

		dma_cookie_complete(txd);



	/* Remove transfer node from the active list. */

	list_del_init(&desc->desc_node);

	spin_unlock_irqrestore(&atchan->lock, flags);



	dma_descriptor_unmap(txd);
@@ -495,6 +493,7 @@ atc_chain_complete(struct at_dma_chan *atchan, struct at_desc *desc) 
 */

static void atc_advance_work(struct at_dma_chan *atchan)

{

	struct at_desc *desc;

	unsigned long flags;



	dev_vdbg(chan2dev(&atchan->chan_common), "advance_work\n");
@@ -502,9 +501,12 @@ static void atc_advance_work(struct at_dma_chan *atchan) 
	spin_lock_irqsave(&atchan->lock, flags);

	if (atc_chan_is_enabled(atchan) || list_empty(&atchan->active_list))

		return spin_unlock_irqrestore(&atchan->lock, flags);

	spin_unlock_irqrestore(&atchan->lock, flags);



	atc_chain_complete(atchan, atc_first_active(atchan));

	desc = atc_first_active(atchan);

	/* Remove the transfer node from the active list. */

	list_del_init(&desc->desc_node);

	spin_unlock_irqrestore(&atchan->lock, flags);

	atc_chain_complete(atchan, desc);



	/* advance work */

	spin_lock_irqsave(&atchan->lock, flags);