linux-kernel - Re: [PATCH] dmaengine: idxd: Check for driver name match before sva user feature

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Date: Wed, 3 Apr 2024 08:23:20 -0700
From: Dave Jiang <dave.jiang@...el.com>
To: Jerry Snitselaar <jsnitsel@...hat.com>, Fenghua Yu <fenghua.yu@...el.com>
Cc: Vinod Koul <vkoul@...nel.org>, dmaengine@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH] dmaengine: idxd: Check for driver name match before sva
 user feature



On 4/2/24 10:07 PM, Jerry Snitselaar wrote:
> Currenty if the user driver is probed on a workqueue configured for
> another driver with SVA not enabled on the system, it will print
> out a number of probe failing messages like the following:
> 
>     [   264.831140] user: probe of wq13.0 failed with error -95
> 
> On some systems, such as GNR, the number of messages can
> reach over 100.
> 
> Move the SVA feature check to be after the driver name match
> check.
> 
> Cc: Vinod Koul <vkoul@...nel.org>
> Cc: dmaengine@...r.kernel.org
> Cc: linux-kernel@...r.kernel.org
> Signed-off-by: Jerry Snitselaar <jsnitsel@...hat.com>

Seems reasonable. Thanks!

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

> ---
>  drivers/dma/idxd/cdev.c | 17 +++++++++--------
>  1 file changed, 9 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/dma/idxd/cdev.c b/drivers/dma/idxd/cdev.c
> index 8078ab9acfbc..a4b771781afc 100644
> --- a/drivers/dma/idxd/cdev.c
> +++ b/drivers/dma/idxd/cdev.c
> @@ -517,6 +517,14 @@ static int idxd_user_drv_probe(struct idxd_dev *idxd_dev)
>  	if (idxd->state != IDXD_DEV_ENABLED)
>  		return -ENXIO;
>  
> +	mutex_lock(&wq->wq_lock);
> +
> +	if (!idxd_wq_driver_name_match(wq, dev)) {
> +		idxd->cmd_status = IDXD_SCMD_WQ_NO_DRV_NAME;
> +		rc = -ENODEV;
> +		goto wq_err;
> +	}
> +
>  	/*
>  	 * User type WQ is enabled only when SVA is enabled for two reasons:
>  	 *   - If no IOMMU or IOMMU Passthrough without SVA, userspace
> @@ -532,14 +540,7 @@ static int idxd_user_drv_probe(struct idxd_dev *idxd_dev)
>  		dev_dbg(&idxd->pdev->dev,
>  			"User type WQ cannot be enabled without SVA.\n");
>  
> -		return -EOPNOTSUPP;
> -	}
> -
> -	mutex_lock(&wq->wq_lock);
> -
> -	if (!idxd_wq_driver_name_match(wq, dev)) {
> -		idxd->cmd_status = IDXD_SCMD_WQ_NO_DRV_NAME;
> -		rc = -ENODEV;
> +		rc = -EOPNOTSUPP;
>  		goto wq_err;
>  	}
>