linux-kernel - [PATCH v2 09/13] dmaengine: at_xdmac: Fix concurrency over xfers

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Message-ID: <20211125090028.786832-10-tudor.ambarus@microchip.com>
Date:   Thu, 25 Nov 2021 11:00:24 +0200
From:   Tudor Ambarus <tudor.ambarus@...rochip.com>
To:     <ludovic.desroches@...rochip.com>, <vkoul@...nel.org>,
        <richard.genoud@...il.com>, <gregkh@...uxfoundation.org>,
        <jirislaby@...nel.org>
CC:     <nicolas.ferre@...rochip.com>, <alexandre.belloni@...tlin.com>,
        <mripard@...nel.org>, <linux-arm-kernel@...ts.infradead.org>,
        <dmaengine@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-serial@...r.kernel.org>,
        Tudor Ambarus <tudor.ambarus@...rochip.com>
Subject: [PATCH v2 09/13] dmaengine: at_xdmac: Fix concurrency over xfers_list

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.

Fixes: e1f7c9eee707 ("dmaengine: at_xdmac: creation of the atmel eXtended DMA Controller driver")
Signed-off-by: Tudor Ambarus <tudor.ambarus@...rochip.com>
---
 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 8804a86a9bcc..81f6f1357dcb 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)
-- 
2.25.1