diff mbox series

[v3,3/9] dmaengine: sun6i: take the device lock before the virtual channel lock

Message ID 20261023-submit-sun6i-dma-lifetime-next-v1-v3-3-ef1acb0be768@gmail.com (mailing list archive)
State New
Headers
Series dmaengine: sun6i: fix interrupt routing and channel lifetime |

Commit Message

James Hilliard Oct. 23, 2026, 11:38 p.m. UTC 
The pending queue is protected by sdev->lock, while virt-dma uses vc.lock
for descriptor lists and cookies. issue_pending() and resume() currently
take the device lock inside the virtual-channel lock when queueing work.

Take sdev->lock first in both paths, and inspect the physical-channel
assignment after acquiring the locks. This establishes the nesting order
needed to keep allocation and descriptor startup in one critical section.
virt-dma preparation, submission and callback processing continue to use
vc.lock independently.

Signed-off-by: James Hilliard <james.hilliard1@gmail.com>
---
 drivers/dma/sun6i-dma.c | 21 ++++++++++-----------
 1 file changed, 10 insertions(+), 11 deletions(-)
diff mbox series

Patch

diff --git a/drivers/dma/sun6i-dma.c b/drivers/dma/sun6i-dma.c
index 3a6525dd3d32..435d7daa1c0f 100644
--- a/drivers/dma/sun6i-dma.c
+++ b/drivers/dma/sun6i-dma.c
@@ -952,23 +952,24 @@  static int sun6i_dma_resume(struct dma_chan *chan)
 {
 	struct sun6i_dma_dev *sdev = to_sun6i_dma_dev(chan->device);
 	struct sun6i_vchan *vchan = to_sun6i_vchan(chan);
-	struct sun6i_pchan *pchan = vchan->phy;
+	struct sun6i_pchan *pchan;
 	unsigned long flags;
 
 	dev_dbg(dmaengine_chan_dev(chan), "vchan %p: resume\n", &vchan->vc);
 
-	spin_lock_irqsave(&vchan->vc.lock, flags);
+	spin_lock_irqsave(&sdev->lock, flags);
+	spin_lock(&vchan->vc.lock);
+	pchan = vchan->phy;
 
 	if (pchan) {
 		writel(DMA_CHAN_PAUSE_RESUME,
 		       pchan->base + DMA_CHAN_PAUSE);
 	} else if (!list_empty(&vchan->vc.desc_issued)) {
-		spin_lock(&sdev->lock);
 		list_add_tail(&vchan->node, &sdev->pending);
-		spin_unlock(&sdev->lock);
 	}
 
-	spin_unlock_irqrestore(&vchan->vc.lock, flags);
+	spin_unlock(&vchan->vc.lock);
+	spin_unlock_irqrestore(&sdev->lock, flags);
 
 	return 0;
 }
@@ -1057,25 +1058,23 @@  static void sun6i_dma_issue_pending(struct dma_chan *chan)
 	struct sun6i_vchan *vchan = to_sun6i_vchan(chan);
 	unsigned long flags;
 
-	spin_lock_irqsave(&vchan->vc.lock, flags);
+	spin_lock_irqsave(&sdev->lock, flags);
+	spin_lock(&vchan->vc.lock);
 
 	if (vchan_issue_pending(&vchan->vc)) {
-		spin_lock(&sdev->lock);
-
 		if (!vchan->phy && list_empty(&vchan->node)) {
 			list_add_tail(&vchan->node, &sdev->pending);
 			tasklet_schedule(&sdev->task);
 			dev_dbg(dmaengine_chan_dev(chan), "vchan %p: issued\n",
 				&vchan->vc);
 		}
-
-		spin_unlock(&sdev->lock);
 	} else {
 		dev_dbg(dmaengine_chan_dev(chan), "vchan %p: nothing to issue\n",
 			&vchan->vc);
 	}
 
-	spin_unlock_irqrestore(&vchan->vc.lock, flags);
+	spin_unlock(&vchan->vc.lock);
+	spin_unlock_irqrestore(&sdev->lock, flags);
 }
 
 static void sun6i_dma_free_chan_resources(struct dma_chan *chan)