dmaengine: fix balance of privatecnt

dma_release_channel() decrements privatecnt counter and almost all dma_get*
function increments it with the exception of dma_get_slave_channel().
In most cases this does not cause issue since normally the channel is not
requested and released, but if a driver requests DMA channel via
dma_get_slave_channel() and releases the channel the privatecnt will be
unbalanced and this will prevent for example getting channel for memcpy.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
index 3ff284c8e3d5aef72f229017c883c73cbe13403f..09479d4be4db3d776fd1f3400724d13f26808428 100644 (file)
--- a/drivers/dma/dmaengine.c
+++ b/drivers/dma/dmaengine.c
@@ -554,10 +554,18 @@ struct dma_chan *dma_get_slave_channel(struct dma_chan *chan)
        mutex_lock(&dma_list_mutex);
 
        if (chan->client_count == 0) {
+               struct dma_device *device = chan->device;
+
+               dma_cap_set(DMA_PRIVATE, device->cap_mask);
+               device->privatecnt++;
                err = dma_chan_get(chan);
-               if (err)
+               if (err) {
                        pr_debug("%s: failed to get %s: (%d)\n",
                                __func__, dma_chan_name(chan), err);
+                       chan = NULL;
+                       if (--device->privatecnt == 0)
+                               dma_cap_clear(DMA_PRIVATE, device->cap_mask);
+               }
        } else
                chan = NULL;