diff options
| author | Duoming Zhou <duoming@zju.edu.cn> | 2023-08-06 11:25:11 +0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-10-19 23:08:58 +0200 |
| commit | 9a995e11b23f4afb4fe50e7d4d420e3ddcaa35a1 (patch) | |
| tree | 7628fef2858409df0873047cd43dfaeba61a06bf | |
| parent | 01b19fc6621d2b10d2433b1f0259f5745e403cd9 (diff) | |
dmaengine: mediatek: Fix deadlock caused by synchronize_irq()
[ Upstream commit 01f1ae2733e2bb4de92fefcea5fda847d92aede1 ]
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>
Signed-off-by: Sasha Levin <sashal@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 a1517ef1f4a0..0acf6a92a4ad 100644 --- a/drivers/dma/mediatek/mtk-uart-apdma.c +++ b/drivers/dma/mediatek/mtk-uart-apdma.c @@ -451,9 +451,8 @@ 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; } |