[PATCH v2] dmaengine: sun6i: Fix potential deadlock on sdev->lock
From: Hongling Zeng <hidden>
Date: 2026-07-06 03:17:30
Also in:
dmaengine, linux-sunxi, lkml, stable
Subsystem:
dma generic offload engine subsystem, the rest · Maintainers:
Vinod Koul, Linus Torvalds
sun6i_dma_terminate_all() and sun6i_dma_pause() acquire sdev->lock
with plain spin_lock() from process context. If a DMA interrupt fires
on the same CPU while the lock is held, the interrupt handler schedules
sun6i_dma_tasklet(), which runs in softirq context and attempts to
acquire the same lock with spin_lock_irq(), causing a deadlock.
Fix by using spin_lock_irq() to disable interrupts while holding
sdev->lock, consistent with other call sites.
Fixes: ba489fd46ab6 ("dmaengine: sun6i: Add support for Allwinner A31 DMA controller")
Cc: stable@vger.kernel.org
Signed-off-by: Hongling Zeng <redacted>
---
Change in v2:
-Fix by using spin_lock_irqsave() and spin_unlock_irqrestore() to
disable interrupts while holding sdev->lock and properly save/restore
interrupt state.
---
drivers/dma/sun6i-dma.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/drivers/dma/sun6i-dma.c b/drivers/dma/sun6i-dma.c
index a9a254dbf8cb..a6487971ad09 100644
--- a/drivers/dma/sun6i-dma.c
+++ b/drivers/dma/sun6i-dma.c@@ -891,6 +891,7 @@ static int sun6i_dma_pause(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; + unsigned long flags; dev_dbg(chan2dev(chan), "vchan %p: pause\n", &vchan->vc);
@@ -898,9 +899,9 @@ static int sun6i_dma_pause(struct dma_chan *chan) writel(DMA_CHAN_PAUSE_PAUSE, pchan->base + DMA_CHAN_PAUSE); } else { - spin_lock(&sdev->lock); + spin_lock_irqsave(&sdev->lock, flags); list_del_init(&vchan->node); - spin_unlock(&sdev->lock); + spin_unlock_irqrestore(&sdev->lock, flags); } return 0;
@@ -939,9 +940,9 @@ static int sun6i_dma_terminate_all(struct dma_chan *chan) unsigned long flags; LIST_HEAD(head); - spin_lock(&sdev->lock); + spin_lock_irqsave(&sdev->lock, flags); list_del_init(&vchan->node); - spin_unlock(&sdev->lock); + spin_unlock_irqrestore(&sdev->lock, flags); spin_lock_irqsave(&vchan->vc.lock, flags);
--
2.25.1