Re: [PATCH] dmaengine: milbeaut-hdmac: Fix deadlock with the channel IRQ handler
flat view
From: Frank Li <hidden>
Date: 2026-09-23 15:23:46
Also in:
dmaengine, linux-mediatek, lkml
On Wed, Sep 23, 2026 at 05:44:26PM +0800, Ginger Li wrote:
[You don't often get email from ginger.jzllee@gmail.com. Learn why this is important at https://aka.ms/LearnAboutSenderIdentification ] milbeaut_hdmac_interrupt() is a hardirq handler and takes mc->vc.lock with a plain spin_lock() for the whole time it runs. interrupts are disabled locally in that context, so the handler itself is fine. milbeaut_hdmac_chan_config(), milbeaut_hdmac_chan_pause() and milbeaut_hdmac_chan_resume() are called from process context and take the same lock with a plain spin_lock() as well, so interrupts stay enabled while the lock is held. If a channel interrupt is delivered on the CPU that is inside one of those critical sections, milbeaut_hdmac_interrupt() spins on a lock that the interrupted code is holding and can never release, and the CPU hangs. Take mc->vc.lock with spin_lock_irqsave() in those three functions, as milbeaut_hdmac_issue_pending() and the other process context users of this lock already do. Fixes: 6c3214e698e4 ("dmaengine: milbeaut-hdmac: Add HDMAC driver for Milbeaut platforms") Signed-off-by: Ginger Li <redacted> ---
Reviewed-by: Frank Li <Frank.Li@nxp.com>
quoted hunk ↗ jump to hunk
drivers/dma/milbeaut-hdmac.c | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-)diff --git a/drivers/dma/milbeaut-hdmac.c b/drivers/dma/milbeaut-hdmac.c --- a/drivers/dma/milbeaut-hdmac.c +++ b/drivers/dma/milbeaut-hdmac.c@@ -214,10 +214,11 @@ milbeaut_hdmac_chan_config(struct dma_chan *chan, stru { struct virt_dma_chan *vc = to_virt_chan(chan); struct milbeaut_hdmac_chan *mc = to_milbeaut_hdmac_chan(vc); + unsigned long flags; - spin_lock(&mc->vc.lock); + spin_lock_irqsave(&mc->vc.lock, flags); mc->cfg = *cfg; - spin_unlock(&mc->vc.lock); + spin_unlock_irqrestore(&mc->vc.lock, flags); return 0; }@@ -226,13 +227,14 @@ static int milbeaut_hdmac_chan_pause(struct dma_chan * { struct virt_dma_chan *vc = to_virt_chan(chan); struct milbeaut_hdmac_chan *mc = to_milbeaut_hdmac_chan(vc); + unsigned long flags; u32 val; - spin_lock(&mc->vc.lock); + spin_lock_irqsave(&mc->vc.lock, flags); val = readl_relaxed(mc->reg_ch_base + MLB_HDMAC_DMACA); val |= MLB_HDMAC_PB; writel_relaxed(val, mc->reg_ch_base + MLB_HDMAC_DMACA); - spin_unlock(&mc->vc.lock); + spin_unlock_irqrestore(&mc->vc.lock, flags); return 0; }@@ -241,13 +243,14 @@ static int milbeaut_hdmac_chan_resume(struct dma_chan { struct virt_dma_chan *vc = to_virt_chan(chan); struct milbeaut_hdmac_chan *mc = to_milbeaut_hdmac_chan(vc); + unsigned long flags; u32 val; - spin_lock(&mc->vc.lock); + spin_lock_irqsave(&mc->vc.lock, flags); val = readl_relaxed(mc->reg_ch_base + MLB_HDMAC_DMACA); val &= ~MLB_HDMAC_PB; writel_relaxed(val, mc->reg_ch_base + MLB_HDMAC_DMACA); - spin_unlock(&mc->vc.lock); + spin_unlock_irqrestore(&mc->vc.lock, flags); return 0; } --2.43.0