linux-kernel - [PATCH] dma: fsl-edma: fix static checker warning of NULL dereference

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Date:	Fri, 21 Feb 2014 14:50:06 +0800
From:	Jingchang Lu <b35083@...escale.com>
To:	<vinod.koul@...el.com>
CC:	<dan.carpenter@...cle.com>, <linux-arm-kernel@...ts.infradead.org>,
	<dmaengine@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	Jingchang Lu <b35083@...escale.com>
Subject: [PATCH] dma: fsl-edma: fix static checker warning of NULL dereference

The static checker reports following warning:
	drivers/dma/fsl-edma.c:732 fsl_edma_xlate()
	error: we previously assumed 'chan' could be null (see line 737)
The changes of the loop cursor in the iteration may result in
NULL dereference when dma_get_slave_channel failed but loop
will continue. So use list_for_each_entry_safe() instead of
list_for_each_entry() to against this.

Reported-by: Dan Carpenter <dan.carpenter@...cle.com>
Signed-off-by: Jingchang Lu <b35083@...escale.com>
---
 drivers/dma/fsl-edma.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/dma/fsl-edma.c b/drivers/dma/fsl-edma.c
index 9025300..381e793 100644
--- a/drivers/dma/fsl-edma.c
+++ b/drivers/dma/fsl-edma.c
@@ -723,13 +723,13 @@ static struct dma_chan *fsl_edma_xlate(struct of_phandle_args *dma_spec,
 		struct of_dma *ofdma)
 {
 	struct fsl_edma_engine *fsl_edma = ofdma->of_dma_data;
-	struct dma_chan *chan;
+	struct dma_chan *chan, *_chan;
 
 	if (dma_spec->args_count != 2)
 		return NULL;
 
 	mutex_lock(&fsl_edma->fsl_edma_mutex);
-	list_for_each_entry(chan, &fsl_edma->dma_dev.channels, device_node) {
+	list_for_each_entry_safe(chan, _chan, &fsl_edma->dma_dev.channels, device_node) {
 		if (chan->client_count)
 			continue;
 		if ((chan->chan_id / DMAMUX_NR) == dma_spec->args[0]) {
-- 
1.8.0


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