[PATCH v3 3/9] dmaengine: dw-edma: Serialize abort state updates

[Koichiro Den]

dw_edma_abort_interrupt() drops vc.lock before changing request and
status. issue_pending() can acquire the lock in that small window,
observe the old busy state, and skip starting queued descriptors. Then
the abort handler overwrites the channel status as idle, leaving the new
descriptors stranded for good.

Keep descriptor completion and the state transition in the same critical
section.

Fixes: e63d79d1ffcd ("dmaengine: Add Synopsys eDMA IP core driver")
Signed-off-by: Koichiro Den <den@xxxxxxxxxxxxx>
---
Changes in v3:
  - New patch for a pre-existing abort state race. (Sashiko)

 drivers/dma/dw-edma/dw-edma-core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/dma/dw-edma/dw-edma-core.c b/drivers/dma/dw-edma/dw-edma-core.c
index 44ef5fbe3fd4..272b03405746 100644
--- a/drivers/dma/dw-edma/dw-edma-core.c
+++ b/drivers/dma/dw-edma/dw-edma-core.c
@@ -740,9 +740,9 @@ static void dw_edma_abort_interrupt(struct dw_edma_chan *chan)
 		list_del(&vd->node);
 		vchan_cookie_complete(vd);
 	}
-	spin_unlock_irqrestore(&chan->vc.lock, flags);
 	chan->request = EDMA_REQ_NONE;
 	chan->status = EDMA_ST_IDLE;
+	spin_unlock_irqrestore(&chan->vc.lock, flags);
 }
 
 static void dw_edma_emul_irq_ack(struct irq_data *d)
-- 
2.51.0