linux-kernel - Re: [PATCH v2] dmaengine: idxd: avoid deadlock in process_misc

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Date:   Tue, 23 Aug 2022 09:46:19 -0700
From:   Dave Jiang <dave.jiang@...el.com>
To:     Jerry Snitselaar <jsnitsel@...hat.com>,
        linux-kernel@...r.kernel.org
Cc:     Fenghua Yu <fenghua.yu@...el.com>, Vinod Koul <vkoul@...nel.org>,
        dmaengine@...r.kernel.org
Subject: Re: [PATCH v2] dmaengine: idxd: avoid deadlock in
 process_misc_interrupts()


On 8/23/2022 9:37 AM, Jerry Snitselaar wrote:
> idxd_device_clear_state() now grabs the idxd->dev_lock
> itself, so don't grab the lock prior to calling it.
>
> This was seen in testing after dmar fault occurred on system,
> resulting in lockup stack traces.
>
> Cc: Fenghua Yu <fenghua.yu@...el.com>
> Cc: Dave Jiang <dave.jiang@...el.com>
> Cc: Vinod Koul <vkoul@...nel.org>
> Cc: dmaengine@...r.kernel.org
> Fixes: cf4ac3fef338 ("dmaengine: idxd: fix lockdep warning on device driver removal")
> Signed-off-by: Jerry Snitselaar <jsnitsel@...hat.com>

Thanks Jerry!

Reviewed-by: Dave Jiang <dave.jiang@...el.com>

> ---
> v2: add Fixes tag, and add subsystem to summary
>
>   drivers/dma/idxd/irq.c | 2 --
>   1 file changed, 2 deletions(-)
>
> diff --git a/drivers/dma/idxd/irq.c b/drivers/dma/idxd/irq.c
> index 743ead5ebc57..5b9921475be6 100644
> --- a/drivers/dma/idxd/irq.c
> +++ b/drivers/dma/idxd/irq.c
> @@ -324,13 +324,11 @@ static int process_misc_interrupts(struct idxd_device *idxd, u32 cause)
>   			idxd->state = IDXD_DEV_HALTED;
>   			idxd_wqs_quiesce(idxd);
>   			idxd_wqs_unmap_portal(idxd);
> -			spin_lock(&idxd->dev_lock);
>   			idxd_device_clear_state(idxd);
>   			dev_err(&idxd->pdev->dev,
>   				"idxd halted, need %s.\n",
>   				gensts.reset_type == IDXD_DEVICE_RESET_FLR ?
>   				"FLR" : "system reset");
> -			spin_unlock(&idxd->dev_lock);
>   			return -ENXIO;
>   		}
>   	}