linux-kernel - [PATCH] dmaengine: at_hdmac: fix module unloading

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Message-Id: <20181127160635.11836-2-richard.genoud@gmail.com>
Date:   Tue, 27 Nov 2018 17:06:35 +0100
From:   Richard Genoud <richard.genoud@...il.com>
To:     Ludovic Desroches <ludovic.desroches@...rochip.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Vinod Koul <vkoul@...nel.org>
Cc:     Alexandre Belloni <alexandre.belloni@...tlin.com>,
        Nicolas Ferre <nicolas.ferre@...rochip.com>,
        Maxime Ripard <maxime.ripard@...tlin.com>,
        Mario Forner <m.forner@...energy.com>,
        linux-arm-kernel@...ts.infradead.org, dmaengine@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-serial@...r.kernel.org,
        Richard Genoud <richard.genoud@...il.com>,
        stable@...r.kernel.org
Subject: [PATCH] dmaengine: at_hdmac: fix module unloading

of_dma_controller_free() was not called on module onloading.
This lead to a soft lockup:
watchdog: BUG: soft lockup - CPU#0 stuck for 23s!
Modules linked in: at_hdmac [last unloaded: at_hdmac]
when of_dma_request_slave_channel() tried to call ofdma->of_dma_xlate().

Cc: stable@...r.kernel.org
Fixes: bbe89c8e3d59 ("at_hdmac: move to generic DMA binding")
Signed-off-by: Richard Genoud <richard.genoud@...il.com>
---
 drivers/dma/at_hdmac.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/dma/at_hdmac.c b/drivers/dma/at_hdmac.c
index 1b7f0ca0d5cd..01d936c9fe89 100644
--- a/drivers/dma/at_hdmac.c
+++ b/drivers/dma/at_hdmac.c
@@ -2006,6 +2006,8 @@ static int at_dma_remove(struct platform_device *pdev)
 	struct resource		*io;
 
 	at_dma_off(atdma);
+	if (pdev->dev.of_node)
+		of_dma_controller_free(pdev->dev.of_node);
 	dma_async_device_unregister(&atdma->dma_common);
 
 	dma_pool_destroy(atdma->memset_pool);