[PATCH v3] dmaengine: sun6i-dma: Fix memory leak in sun6i_dma_terminate_all

[Hongling Zeng]

When terminating a non-cyclic DMA transfer, the active descriptor
is not properly reclaimed. The descriptor is removed from the
desc_issued list in sun6i_dma_start_desc(), but in
sun6i_dma_terminate_all(), only cyclic transfer descriptors are
added to the desc_completed list before cleanup.

For non-cyclic transfers, pchan->desc is set to NULL without first
adding the descriptor back to a list that vchan_get_all_descriptors()
can collect. This causes the descriptor and its associated LLI chain
to be permanently leaked.

Fix by ensuring both cyclic and non-cyclic active descriptors are
added to the desc_completed list before setting pchan->desc to NULL.

Fixes: 555859308723 ("dmaengine: sun6i: Add driver for the Allwinner A31 DMA controller")
Signed-off-by: Hongling Zeng <zenghongling at kylinos.cn>
Acked-by: Jernej Skrabec <jernej.skrabec at gmail.com>
Suggested-by: Frank Li <Frank.li at oss.nxp.com>

---
 Change in v2;
 -Add pchan->desc != pchan->done check to prevent race condition
  where completed descriptors could be double-added to desc_completed
  list, causing list corruption
---
 Change in v3:
 -Fix by using vchan_terminate_vdesc() as suggested by Frank Li
---
 drivers/dma/sun6i-dma.c | 13 +++++--------
 1 file changed, 5 insertions(+), 8 deletions(-)

diff --git a/drivers/dma/sun6i-dma.c b/drivers/dma/sun6i-dma.c
index 7a79f346250a..134ae840f176 100644
--- a/drivers/dma/sun6i-dma.c
+++ b/drivers/dma/sun6i-dma.c
@@ -946,16 +946,13 @@ static int sun6i_dma_terminate_all(struct dma_chan *chan)
 
 	spin_lock_irqsave(&vchan->vc.lock, flags);
 
-	if (vchan->cyclic) {
-		vchan->cyclic = false;
-		if (pchan && pchan->desc) {
-			struct virt_dma_desc *vd = &pchan->desc->vd;
-			struct virt_dma_chan *vc = &vchan->vc;
-
-			list_add_tail(&vd->node, &vc->desc_completed);
-		}
+	if (pchan && pchan->desc && pchan->desc != pchan->done) {
+		struct virt_dma_desc *vd = &pchan->desc->vd;
+		
+		vchan_terminate_vdesc(vd);
 	}
 
+	vchan->cyclic = false;
 	vchan_get_all_descriptors(&vchan->vc, &head);
 
 	if (pchan) {
-- 
2.25.1