re: dmaengine: add interface of dma_get_slave_channel

Dan Carpenter
2013-08-14T19:51:20Z

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