From 18deddea9184b62941395889ff7659529c877326 Mon Sep 17 00:00:00 2001

From: Tudor Ambarus <tudor.ambarus@microchip.com>

Date: Wed, 15 Dec 2021 13:01:10 +0200

Subject: [PATCH] dmaengine: at_xdmac: Fix concurrency over xfers_list

Git-commit: 18deddea9184b62941395889ff7659529c877326

Patch-mainline: v5.17-rc1

References: git-fixes

Since tx_submit can be called from a hard IRQ, xfers_list must be

protected with a lock to avoid concurency on the list's elements.

Since at_xdmac_handle_cyclic() is called from a tasklet, spin_lock_irq

is enough to protect from a hard IRQ.

Fixes: e1f7c9eee707 ("dmaengine: at_xdmac: creation of the atmel eXtended DMA Controller driver")

Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>

Link: https://lore.kernel.org/r/20211215110115.191749-8-tudor.ambarus@microchip.com

Signed-off-by: Vinod Koul <vkoul@kernel.org>

Acked-by: Takashi Iwai <tiwai@suse.de>

---

 drivers/dma/at_xdmac.c | 17 ++++++++++-------

 1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/drivers/dma/at_xdmac.c b/drivers/dma/at_xdmac.c

index b6547f1b5645..eeb03065d484 100644

--- a/drivers/dma/at_xdmac.c

+++ b/drivers/dma/at_xdmac.c

@@ -1608,14 +1608,17 @@ static void at_xdmac_handle_cyclic(struct at_xdmac_chan *atchan)

 	struct at_xdmac_desc		*desc;

 	struct dma_async_tx_descriptor	*txd;

-	if (!list_empty(&atchan->xfers_list)) {

-		desc = list_first_entry(&atchan->xfers_list,

-					struct at_xdmac_desc, xfer_node);

-		txd = &desc->tx_dma_desc;

-

-		if (txd->flags & DMA_PREP_INTERRUPT)

-			dmaengine_desc_get_callback_invoke(txd, NULL);

+	spin_lock_irq(&atchan->lock);

+	if (list_empty(&atchan->xfers_list)) {

+		spin_unlock_irq(&atchan->lock);

+		return;

 	}

+	desc = list_first_entry(&atchan->xfers_list, struct at_xdmac_desc,

+				xfer_node);

+	spin_unlock_irq(&atchan->lock);

+	txd = &desc->tx_dma_desc;

+	if (txd->flags & DMA_PREP_INTERRUPT)

+		dmaengine_desc_get_callback_invoke(txd, NULL);

 }

 static void at_xdmac_handle_error(struct at_xdmac_chan *atchan)

-- 

2.31.1