diff options
| author | Duoming Zhou <duoming@zju.edu.cn> | 2023-08-06 06:25:11 +0300 |
|---|---|---|
| committer | Vinod Koul <vkoul@kernel.org> | 2023-10-04 16:56:36 +0300 |
| commit | 01f1ae2733e2bb4de92fefcea5fda847d92aede1 (patch) | |
| tree | bbe74fd11ee615dbf570fa24e15205867c3a3d59 | |
| parent | c0409dd3d151f661e7e57b901a81a02565df163c (diff) | |
| download | linux-01f1ae2733e2bb4de92fefcea5fda847d92aede1.tar.xz | |
dmaengine: mediatek: Fix deadlock caused by synchronize_irq()
The synchronize_irq(c->irq) will not return until the IRQ handler
mtk_uart_apdma_irq_handler() is completed. If the synchronize_irq()
holds a spin_lock and waits the IRQ handler to complete, but the
IRQ handler also needs the same spin_lock. The deadlock will happen.
The process is shown below:
cpu0 cpu1
mtk_uart_apdma_device_pause() | mtk_uart_apdma_irq_handler()
spin_lock_irqsave() |
| spin_lock_irqsave()
//hold the lock to wait |
synchronize_irq() |
This patch reorders the synchronize_irq(c->irq) outside the spin_lock
in order to mitigate the bug.
Fixes: 9135408c3ace ("dmaengine: mediatek: Add MediaTek UART APDMA support")
Signed-off-by: Duoming Zhou <duoming@zju.edu.cn>
Reviewed-by: Eugen Hristev <eugen.hristev@collabora.com>
Link: https://lore.kernel.org/r/20230806032511.45263-1-duoming@zju.edu.cn
Signed-off-by: Vinod Koul <vkoul@kernel.org>
| -rw-r--r-- | drivers/dma/mediatek/mtk-uart-apdma.c | 3 |
1 files changed, 1 insertions, 2 deletions
diff --git a/drivers/dma/mediatek/mtk-uart-apdma.c b/drivers/dma/mediatek/mtk-uart-apdma.c index c51dc017b48a..06d12ac39144 100644 --- a/drivers/dma/mediatek/mtk-uart-apdma.c +++ b/drivers/dma/mediatek/mtk-uart-apdma.c @@ -450,9 +450,8 @@ static int mtk_uart_apdma_device_pause(struct dma_chan *chan) mtk_uart_apdma_write(c, VFF_EN, VFF_EN_CLR_B); mtk_uart_apdma_write(c, VFF_INT_EN, VFF_INT_EN_CLR_B); - synchronize_irq(c->irq); - spin_unlock_irqrestore(&c->vc.lock, flags); + synchronize_irq(c->irq); return 0; } |