[PATCH 3/3] dmaengine: dw-axi-dmac: ignore interrupt if no descriptor

[Ben Dooks <ben.dooks@sifive.com>]

If the channel has no descriptor and the interrupt is raised then the
kernel will OOPS. Check the result of vchan_next_desc() in the handler
axi_chan_block_xfer_complete() to avoid the error happening.

Signed-off-by: Ben Dooks <ben.dooks@sifive.com>
---
 drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c b/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c
index d6ef5f49f281..1fedf4376678 100644
--- a/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c
+++ b/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c
@@ -1082,6 +1082,11 @@ static void axi_chan_block_xfer_complete(struct axi_dma_chan *chan)
 
 	/* The completed descriptor currently is in the head of vc list */
 	vd = vchan_next_desc(&chan->vc);
+	if (!vd) {
+		dev_err(chan2dev(chan), "BUG: %s, IRQ with no descriptors\n",
+			axi_chan_name(chan));
+		goto out;
+	}
 
 	if (chan->cyclic) {
 		desc = vd_to_axi_desc(vd);
@@ -1111,6 +1116,7 @@ static void axi_chan_block_xfer_complete(struct axi_dma_chan *chan)
 		axi_chan_start_first_queued(chan);
 	}
 
+out:
 	spin_unlock_irqrestore(&chan->vc.lock, flags);
 }
 
-- 
2.35.1