dmaengine: dw-axi-dmac: ignore interrupt if no descriptor

[ Upstream commit 820f5ce999d2f99961e88c16d65cd26764df0590 ]

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>
Link: https://lore.kernel.org/r/20220708170153.269991-4-ben.dooks@sifive.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

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 8f765e2..48de8d2 100644 (file)
--- a/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c
+++ b/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c
@@ -1016,6 +1016,11 @@ 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);
@@ -1045,6 +1050,7 @@ 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);
 }