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From:   Tim van der Staaij | Zign <Tim.vanderstaaij@zigngroup.com>
To:     Shawn Guo <shawnguo@kernel.org>,
        Sascha Hauer <s.hauer@pengutronix.de>
CC:     Vinod Koul <vkoul@kernel.org>,
        Pengutronix Kernel Team <kernel@pengutronix.de>,
        Fabio Estevam <festevam@gmail.com>,
        "dmaengine@vger.kernel.org" <dmaengine@vger.kernel.org>,
        "linux-arm-kernel@lists.infradead.org" 
        <linux-arm-kernel@lists.infradead.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: [PATCH] dmaengine: imx-sdma: fix deadlock in interrupt handler
Thread-Topic: [PATCH] dmaengine: imx-sdma: fix deadlock in interrupt handler
Thread-Index: AQHZ7HFXCtmZOIdMP0ek3TzK7ZAfKw==
Date:   Thu, 21 Sep 2023 09:57:11 +0000
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dev_warn internally acquires the lock that is already held when=0A=
sdma_update_channel_loop is called. Therefore it is acquired twice and=0A=
this is detected as a deadlock. Temporarily release the lock while=0A=
logging to avoid this.=0A=
=0A=
Signed-off-by: Tim van der Staaij <tim.vanderstaaij@zigngroup.com>=0A=
Link: https://lore.kernel.org/all/AM0PR08MB308979EC3A8A53AE6E2D3408802CA@AM=
0PR08MB3089.eurprd08.prod.outlook.com/=0A=
---=0A=
 drivers/dma/imx-sdma.c | 3 +++=0A=
 1 file changed, 3 insertions(+)=0A=
=0A=
diff --git a/drivers/dma/imx-sdma.c b/drivers/dma/imx-sdma.c=0A=
index 51012bd39900..3a7cd783a567 100644=0A=
--- a/drivers/dma/imx-sdma.c=0A=
+++ b/drivers/dma/imx-sdma.c=0A=
@@ -904,7 +904,10 @@ static void sdma_update_channel_loop(struct sdma_chann=
el *sdmac)=0A=
 	 * owned buffer is available (i.e. BD_DONE was set too late).=0A=
 	 */=0A=
 	if (sdmac->desc && !is_sdma_channel_enabled(sdmac->sdma, sdmac->channel))=
 {=0A=
+		spin_unlock(&sdmac->vc.lock);=0A=
 		dev_warn(sdmac->sdma->dev, "restart cyclic channel %d\n", sdmac->channel=
);=0A=
+		spin_lock(&sdmac->vc.lock);=0A=
+=0A=
 		sdma_enable_channel(sdmac->sdma, sdmac->channel);=0A=
 	}=0A=
 }=0A=
-- =0A=
2.41.0=0A=