Re: [PATCH V2 3/3] dmaengine: zynqmp_dma: Guard IRQ handler against spurious interrupts

[Frank Li <Frank.li@oss.nxp.com>]

On Thu, Jun 18, 2026 at 12:40:56PM +0530, Golla Nagendra wrote:
> [You don't often get email from nagendra.golla@amd.com. Learn why this is important at https://aka.ms/LearnAboutSenderIdentification ]
>
> Add pm_runtime_get_if_active() check in zynqmp_dma_irq_handler() to
> safely handle spurious interrupts that may arrive while the device is
> runtime-suspended. Without this guard, a spurious interrupt could cause
> the handler to access hardware registers (ISR, IMR) with clocks gated,
> potentially leading to a synchronous external abort and kernel crash.
>
> When the device is not runtime-active, pm_runtime_get_if_active()
> returns false without incrementing the usage counter, and the handler
> returns IRQ_NONE immediately. When the device is active, it increments
> the usage counter to prevent a concurrent runtime suspend during
> register access, and pm_runtime_put() releases the reference afterward.
>
> Signed-off-by: Golla Nagendra <nagendra.golla@amd.com>
> ---
>  drivers/dma/xilinx/zynqmp_dma.c | 5 +++++
>  1 file changed, 5 insertions(+)
>
> diff --git a/drivers/dma/xilinx/zynqmp_dma.c b/drivers/dma/xilinx/zynqmp_dma.c
> index a9dfec3c0ca3..ce9163138be7 100644
> --- a/drivers/dma/xilinx/zynqmp_dma.c
> +++ b/drivers/dma/xilinx/zynqmp_dma.c
> @@ -730,6 +730,9 @@ static irqreturn_t zynqmp_dma_irq_handler(int irq, void *data)
>         u32 isr, imr, status;
>         irqreturn_t ret = IRQ_NONE;
>
> +       if (pm_runtime_get_if_active(chan->dev) <= 0)
> +               return IRQ_NONE;
> +

Can you add AQUIRE macro in include/linux/pm_runtime.h
so here can use PM_RUNTIME_ACQUIRE_IF_ACITVE

Other person can get benefit for auto clean up especially if there are some
difference return path.

Frank

>         isr = readl(chan->regs + ZYNQMP_DMA_ISR);
>         imr = readl(chan->regs + ZYNQMP_DMA_IMR);
>         status = isr & ~imr;
> @@ -756,6 +759,8 @@ static irqreturn_t zynqmp_dma_irq_handler(int irq, void *data)
>                 ret = IRQ_HANDLED;
>         }
>
> +       pm_runtime_put(chan->dev);
> +
>         return ret;
>  }
>
> --
> 2.34.1
>