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From:   Tudor Ambarus <tudor.ambarus@microchip.com>
To:     <ludovic.desroches@microchip.com>, <vkoul@kernel.org>,
        <richard.genoud@gmail.com>, <gregkh@linuxfoundation.org>,
        <jirislaby@kernel.org>
CC:     <nicolas.ferre@microchip.com>, <alexandre.belloni@bootlin.com>,
        <mripard@kernel.org>, <linux-arm-kernel@lists.infradead.org>,
        <dmaengine@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        <linux-serial@vger.kernel.org>,
        Tudor Ambarus <tudor.ambarus@microchip.com>
Subject: [PATCH 09/13] dmaengine: at_xdmac: Fix concurrency over xfers_list
Date:   Tue, 16 Nov 2021 13:20:32 +0200
Message-ID: <20211116112036.96349-10-tudor.ambarus@microchip.com>
In-Reply-To: <20211116112036.96349-1-tudor.ambarus@microchip.com>
References: <20211116112036.96349-1-tudor.ambarus@microchip.com>
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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@microchip.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