On 13-08-15 03:51 AM, Dan Carpenter wrote:
Hello Zhangfei Gao,
The patch 7bb587f4eef8: "dmaengine: add interface of
dma_get_slave_channel" from Jun 28, 2013, leads to the following
warning: "drivers/dma/dmaengine.c:531 dma_get_slave_channel()
error: potential NULL dereference 'chan'."
drivers/dma/dmaengine.c
516 struct dma_chan *dma_get_slave_channel(struct dma_chan *chan)
517 {
518 int err = -EBUSY;
519
520 /* lock against __dma_request_channel */
521 mutex_lock(&dma_list_mutex);
522
523 if (chan->client_count == 0)
524 err = dma_chan_get(chan);
525 else
526 chan = NULL;
^^^^^^^^^^^
527
528 mutex_unlock(&dma_list_mutex);
529
530 if (err)
531 pr_debug("%s: failed to get %s: (%d)\n",
532 __func__, dma_chan_name(chan), err);
^^^^
Dereferenced here.
533
534 return chan;
regards,
dan carpenter
Thanks Dan for point out.
I am sorry, make does not report such error here, is it config related.
Dear Vinod
Could I update this patch and resend to you?
Change to:
struct dma_chan *dma_get_slave_channel(struct dma_chan *chan)
{
int err = -EBUSY;
/* lock against __dma_request_channel */
mutex_lock(&dma_list_mutex);
if (chan->client_count == 0) {
err = dma_chan_get(chan);
if (err)
pr_debug("%s: failed to get %s: (%d)\n",
__func__, dma_chan_name(chan), err);
} else
chan = NULL;
mutex_unlock(&dma_list_mutex);
return chan;
}
Sorry for inconvenience.
Thanks
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