linux-kernel - Re: [PATCH v2 01/10] dmaengine: idxd: Fix lockdep warnings when calling idxd_device

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Message-ID: <bc336eeb-2456-4321-92fa-3be9eba15f4e@intel.com>
Date: Thu, 21 Aug 2025 16:05:34 -0700
From: Dave Jiang <dave.jiang@...el.com>
To: Vinicius Costa Gomes <vinicius.gomes@...el.com>,
 Vinod Koul <vkoul@...nel.org>, Fenghua Yu <fenghua.yu@...el.com>,
 Dan Williams <dan.j.williams@...el.com>
Cc: dmaengine@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 01/10] dmaengine: idxd: Fix lockdep warnings when
 calling idxd_device_config()



On 8/21/25 3:59 PM, Vinicius Costa Gomes wrote:
> Move the check for IDXD_FLAG_CONFIGURABLE and the locking to "inside"
> idxd_device_config(), as this is common to all callers, and the one
> that wasn't holding the lock was an error (that was causing the
> lockdep warning).
> 
> Suggested-by: Dave Jiang <dave.jiang@...el.com>
> Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@...el.com>
Reviewed-by: Dave Jiang <dave.jiang@...el.com>
> ---
>  drivers/dma/idxd/device.c | 17 +++++++----------
>  drivers/dma/idxd/init.c   | 10 ++++------
>  2 files changed, 11 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/dma/idxd/device.c b/drivers/dma/idxd/device.c
> index 5cf419fe6b46..ac41889e4fe1 100644
> --- a/drivers/dma/idxd/device.c
> +++ b/drivers/dma/idxd/device.c
> @@ -1107,7 +1107,11 @@ int idxd_device_config(struct idxd_device *idxd)
>  {
>  	int rc;
>  
> -	lockdep_assert_held(&idxd->dev_lock);
> +	guard(spinlock)(&idxd->dev_lock);
> +
> +	if (!test_bit(IDXD_FLAG_CONFIGURABLE, &idxd->flags))
> +		return 0;
> +
>  	rc = idxd_wqs_setup(idxd);
>  	if (rc < 0)
>  		return rc;
> @@ -1434,11 +1438,7 @@ int idxd_drv_enable_wq(struct idxd_wq *wq)
>  		}
>  	}
>  
> -	rc = 0;
> -	spin_lock(&idxd->dev_lock);
> -	if (test_bit(IDXD_FLAG_CONFIGURABLE, &idxd->flags))
> -		rc = idxd_device_config(idxd);
> -	spin_unlock(&idxd->dev_lock);
> +	rc = idxd_device_config(idxd);
>  	if (rc < 0) {
>  		dev_dbg(dev, "Writing wq %d config failed: %d\n", wq->id, rc);
>  		goto err;
> @@ -1534,10 +1534,7 @@ int idxd_device_drv_probe(struct idxd_dev *idxd_dev)
>  	}
>  
>  	/* Device configuration */
> -	spin_lock(&idxd->dev_lock);
> -	if (test_bit(IDXD_FLAG_CONFIGURABLE, &idxd->flags))
> -		rc = idxd_device_config(idxd);
> -	spin_unlock(&idxd->dev_lock);
> +	rc = idxd_device_config(idxd);
>  	if (rc < 0)
>  		return -ENXIO;
>  
> diff --git a/drivers/dma/idxd/init.c b/drivers/dma/idxd/init.c
> index f98aa41fa42e..c25bd0595561 100644
> --- a/drivers/dma/idxd/init.c
> +++ b/drivers/dma/idxd/init.c
> @@ -1092,12 +1092,10 @@ static void idxd_reset_done(struct pci_dev *pdev)
>  	idxd_device_config_restore(idxd, idxd->idxd_saved);
>  
>  	/* Re-configure IDXD device if allowed. */
> -	if (test_bit(IDXD_FLAG_CONFIGURABLE, &idxd->flags)) {
> -		rc = idxd_device_config(idxd);
> -		if (rc < 0) {
> -			dev_err(dev, "HALT: %s config fails\n", idxd_name);
> -			goto out;
> -		}
> +	rc = idxd_device_config(idxd);
> +	if (rc < 0) {
> +		dev_err(dev, "HALT: %s config fails\n", idxd_name);
> +		goto out;
>  	}
>  
>  	/* Bind IDXD device to driver. */
>