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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        Ludovic Desroches <ludovic.desroches@microchip.com>,
        Richard Genoud <richard.genoud@gmail.com>,
        Vinod Koul <vkoul@kernel.org>
Subject: [PATCH 4.4 16/91] dmaengine: at_hdmac: fix module unloading
Date:   Tue, 11 Dec 2018 16:40:35 +0100
Message-Id: <20181211151607.203912382@linuxfoundation.org>
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4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Richard Genoud <richard.genoud@gmail.com>

commit 77e75fda94d2ebb86aa9d35fb1860f6395bf95de upstream.

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@vger.kernel.org
Fixes: bbe89c8e3d59 ("at_hdmac: move to generic DMA binding")
Acked-by: Ludovic Desroches <ludovic.desroches@microchip.com>
Signed-off-by: Richard Genoud <richard.genoud@gmail.com>
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/dma/at_hdmac.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/drivers/dma/at_hdmac.c
+++ b/drivers/dma/at_hdmac.c
@@ -2152,6 +2152,8 @@ static int at_dma_remove(struct platform
 	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);