linux-kernel - [PATCH] dmaengine: at_hdmac: do exception handling appropriately in at_dma

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Date:   Wed, 29 Jul 2020 20:29:03 +0800
From:   Yu Kuai <yukuai3@...wei.com>
To:     <ludovic.desroches@...rochip.com>, <tudor.ambarus@...rochip.com>,
        <vkoul@...nel.org>, <dan.j.williams@...el.com>, <arnd@...db.de>,
        <nicolas.ferre@...rochip.com>, <plagnioj@...osoft.com>
CC:     <linux-arm-kernel@...ts.infradead.org>,
        <dmaengine@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <yi.zhang@...wei.com>, <yukuai3@...wei.com>
Subject: [PATCH] dmaengine: at_hdmac: do exception handling appropriately in at_dma_xlate()

Do several things for exception handing:

a. check return value of of_find_device_by_node().
b. call put_device() if memory allocation for 'atslave' failed.
c. if dma_request_channel() failed, call put_device() and kfree().

Fixes: bbe89c8e3d59 ("at_hdmac: move to generic DMA binding")
Signed-off-by: Yu Kuai <yukuai3@...wei.com>
---
 drivers/dma/at_hdmac.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/dma/at_hdmac.c b/drivers/dma/at_hdmac.c
index 45bbcd6146fd..a2cf25c6e3b3 100644
--- a/drivers/dma/at_hdmac.c
+++ b/drivers/dma/at_hdmac.c
@@ -1650,13 +1650,17 @@ static struct dma_chan *at_dma_xlate(struct of_phandle_args *dma_spec,
 		return NULL;
 
 	dmac_pdev = of_find_device_by_node(dma_spec->np);
+	if (!dmac_pdev)
+		return NULL;
 
 	dma_cap_zero(mask);
 	dma_cap_set(DMA_SLAVE, mask);
 
 	atslave = kmalloc(sizeof(*atslave), GFP_KERNEL);
-	if (!atslave)
+	if (!atslave) {
+		put_device(&dmac_pdev->dev);
 		return NULL;
+	}
 
 	atslave->cfg = ATC_DST_H2SEL_HW | ATC_SRC_H2SEL_HW;
 	/*
@@ -1685,8 +1689,11 @@ static struct dma_chan *at_dma_xlate(struct of_phandle_args *dma_spec,
 	atslave->dma_dev = &dmac_pdev->dev;
 
 	chan = dma_request_channel(mask, at_dma_filter, atslave);
-	if (!chan)
+	if (!chan) {
+		put_device(&dmac_pdev->dev);
+		kfree(atslave);
 		return NULL;
+	}
 
 	atchan = to_at_dma_chan(chan);
 	atchan->per_if = dma_spec->args[0] & 0xff;
-- 
2.25.4