dmaengine: sprd: Fix the possible memory leak issue

If we terminate the channel to free all descriptors associated with this
channel, we will leak the memory of current descriptor if the current
descriptor is not completed, since it had been deteled from the desc_issued
list and have not been added into the desc_completed list.

Thus we should check if current descriptor is completed or not, when freeing
the descriptors associated with one channel, if not, we should free it to
avoid this issue.

Fixes: 9b3b817 ("dmaengine: sprd: Add Spreadtrum DMA driver")
Reported-by: Zhenfang Wang <zhenfang.wang@unisoc.com>
Tested-by: Zhenfang Wang <zhenfang.wang@unisoc.com>
Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
Link: https://lore.kernel.org/r/170dbbc6d5366b6fa974ce2d366652e23a334251.1570609788.git.baolin.wang@linaro.org
Signed-off-by: Vinod Koul <vkoul@kernel.org>

drivers/dma/sprd-dma.c

@@ -212,6 +212,7 @@ struct sprd_dma_dev {
 	struct sprd_dma_chn	channels[0];
 };
 
+static void sprd_dma_free_desc(struct virt_dma_desc *vd);
 static bool sprd_dma_filter_fn(struct dma_chan *chan, void *param);
 static struct of_dma_filter_info sprd_dma_info = {
 	.filter_fn = sprd_dma_filter_fn,
@@ -613,12 +614,19 @@ static int sprd_dma_alloc_chan_resources(struct dma_chan *chan)
 static void sprd_dma_free_chan_resources(struct dma_chan *chan)
 {
 	struct sprd_dma_chn *schan = to_sprd_dma_chan(chan);
+	struct virt_dma_desc *cur_vd = NULL;
 	unsigned long flags;
 
 	spin_lock_irqsave(&schan->vc.lock, flags);
+	if (schan->cur_desc)
+		cur_vd = &schan->cur_desc->vd;
+
 	sprd_dma_stop(schan);
 	spin_unlock_irqrestore(&schan->vc.lock, flags);
 
+	if (cur_vd)
+		sprd_dma_free_desc(cur_vd);
+
 	vchan_free_chan_resources(&schan->vc);
 	pm_runtime_put(chan->device->dev);
 }
@@ -1031,15 +1039,22 @@ static int sprd_dma_resume(struct dma_chan *chan)
 static int sprd_dma_terminate_all(struct dma_chan *chan)
 {
 	struct sprd_dma_chn *schan = to_sprd_dma_chan(chan);
+	struct virt_dma_desc *cur_vd = NULL;
 	unsigned long flags;
 	LIST_HEAD(head);
 
 	spin_lock_irqsave(&schan->vc.lock, flags);
+	if (schan->cur_desc)
+		cur_vd = &schan->cur_desc->vd;
+
 	sprd_dma_stop(schan);
 
 	vchan_get_all_descriptors(&schan->vc, &head);
 	spin_unlock_irqrestore(&schan->vc.lock, flags);
 
+	if (cur_vd)
+		sprd_dma_free_desc(cur_vd);
+
 	vchan_dma_desc_free_list(&schan->vc, &head);
 	return 0;
 }