linux-kernel - Re: [PATCH 7/9] iommu/of: Use helper functions to access dev->iommu

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Date:   Wed, 5 Dec 2018 17:41:51 +0000
From:   Robin Murphy <robin.murphy@....com>
To:     Joerg Roedel <joro@...tes.org>, iommu@...ts.linux-foundation.org
Cc:     Joerg Roedel <jroedel@...e.de>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 7/9] iommu/of: Use helper functions to access
 dev->iommu_fwspec

On 04/12/2018 16:30, Joerg Roedel wrote:
> From: Joerg Roedel <jroedel@...e.de>
> 
> Use the new helpers dev_iommu_fwspec_get()/set() to access
> the dev->iommu_fwspec pointer. This makes it easier to move
> that pointer later into another struct.
> 
> Signed-off-by: Joerg Roedel <jroedel@...e.de>
> ---
>   drivers/iommu/of_iommu.c | 7 +++++--
>   1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/iommu/of_iommu.c b/drivers/iommu/of_iommu.c
> index c5dd63072529..38232250b5f4 100644
> --- a/drivers/iommu/of_iommu.c
> +++ b/drivers/iommu/of_iommu.c
> @@ -164,7 +164,7 @@ const struct iommu_ops *of_iommu_configure(struct device *dev,
>   					   struct device_node *master_np)
>   {
>   	const struct iommu_ops *ops = NULL;
> -	struct iommu_fwspec *fwspec = dev->iommu_fwspec;
> +	struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
>   	int err = NO_IOMMU;
>   
>   	if (!master_np)
> @@ -208,6 +208,9 @@ const struct iommu_ops *of_iommu_configure(struct device *dev,
>   		}
>   	}
>   
> +	/* The fwspec pointer changed, read it again */
> +	fwspec = dev_iommu_fwspec_get(dev);

Nit: I think it makes sense to put this inside the "if (!err)" condition 
below rather than out here where it may or may not be relevant. The 
comment for that case is already supposed to imply that it's dealing 
with a fresh fwspec.

Robin.

> +
>   	/*
>   	 * Two success conditions can be represented by non-negative err here:
>   	 * >0 : there is no IOMMU, or one was unavailable for non-fatal reasons
> @@ -215,7 +218,7 @@ const struct iommu_ops *of_iommu_configure(struct device *dev,
>   	 * <0 : any actual error
>   	 */
>   	if (!err)
> -		ops = dev->iommu_fwspec->ops;
> +		ops = fwspec->ops;
>   	/*
>   	 * If we have reason to believe the IOMMU driver missed the initial
>   	 * add_device callback for dev, replay it to get things in order.
>