linux-kernel - Re: [PATCH 06/15] iommu: Move iommu_fwspec to struct dev

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Date:   Mon, 16 Mar 2020 16:46:54 +0100
From:   Jean-Philippe Brucker <jean-philippe@...aro.org>
To:     Joerg Roedel <joro@...tes.org>
Cc:     iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, linux-mediatek@...ts.infradead.org,
        virtualization@...ts.linux-foundation.org,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Hanjun Guo <guohanjun@...wei.com>,
        Sudeep Holla <sudeep.holla@....com>,
        Rob Clark <robdclark@...il.com>, Sean Paul <sean@...rly.run>,
        Will Deacon <will@...nel.org>,
        Robin Murphy <robin.murphy@....com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Thierry Reding <thierry.reding@...il.com>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Joerg Roedel <jroedel@...e.de>
Subject: Re: [PATCH 06/15] iommu: Move iommu_fwspec to struct dev_iommu

On Tue, Mar 10, 2020 at 10:12:20AM +0100, Joerg Roedel wrote:
> From: Joerg Roedel <jroedel@...e.de>
> 
> Move the iommu_fwspec pointer in struct device into struct dev_iommu.
> This is a step in the effort to reduce the iommu related pointers in
> struct device to one.
> 
> Tested-by: Will Deacon <will@...nel.org> # arm-smmu
> Signed-off-by: Joerg Roedel <jroedel@...e.de>
> ---
>  drivers/iommu/iommu.c  |  3 +++
>  include/linux/device.h |  1 -
>  include/linux/iommu.h  | 12 ++++++++----
>  3 files changed, 11 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index beac2ef063dd..826a67ba247f 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -2405,6 +2405,9 @@ int iommu_fwspec_init(struct device *dev, struct fwnode_handle *iommu_fwnode,
>  	if (fwspec)
>  		return ops == fwspec->ops ? 0 : -EINVAL;
>  
> +	if (!dev_iommu_get(dev))
> +		return -ENOMEM;
> +
>  	fwspec = kzalloc(sizeof(*fwspec), GFP_KERNEL);
>  	if (!fwspec)
>  		return -ENOMEM;
> diff --git a/include/linux/device.h b/include/linux/device.h
> index 405a8f11bec1..ca29c39a6480 100644
> --- a/include/linux/device.h
> +++ b/include/linux/device.h
> @@ -613,7 +613,6 @@ struct device {
>  
>  	void	(*release)(struct device *dev);
>  	struct iommu_group	*iommu_group;
> -	struct iommu_fwspec	*iommu_fwspec;
>  	struct dev_iommu	*iommu;
>  
>  	bool			offline_disabled:1;
> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> index 1c9fa5c1174b..f5edc21a644d 100644
> --- a/include/linux/iommu.h
> +++ b/include/linux/iommu.h
> @@ -368,14 +368,15 @@ struct iommu_fault_param {
>   * struct dev_iommu - Collection of per-device IOMMU data
>   *
>   * @fault_param: IOMMU detected device fault reporting data
> + * @fwspec:	 IOMMU fwspec data
>   *
>   * TODO: migrate other per device data pointers under iommu_dev_data, e.g.
>   *	struct iommu_group	*iommu_group;
> - *	struct iommu_fwspec	*iommu_fwspec;
>   */
>  struct dev_iommu {
>  	struct mutex lock;
> -	struct iommu_fault_param *fault_param;
> +	struct iommu_fault_param	*fault_param;
> +	struct iommu_fwspec		*fwspec;
>  };
>  
>  int  iommu_device_register(struct iommu_device *iommu);
> @@ -614,13 +615,16 @@ const struct iommu_ops *iommu_ops_from_fwnode(struct fwnode_handle *fwnode);
>  
>  static inline struct iommu_fwspec *dev_iommu_fwspec_get(struct device *dev)
>  {
> -	return dev->iommu_fwspec;
> +	if (dev->iommu)
> +		return dev->iommu->fwspec;
> +	else
> +		return NULL;
>  }
>  
>  static inline void dev_iommu_fwspec_set(struct device *dev,
>  					struct iommu_fwspec *fwspec)
>  {
> -	dev->iommu_fwspec = fwspec;
> +	dev->iommu->fwspec = fwspec;

It may be worth moving the set() to iommu.c and prevent any misuse.
Regardless:

Reviewed-by: Jean-Philippe Brucker <jean-philippe@...aro.org>

>  }
>  
>  int iommu_probe_device(struct device *dev);
> -- 
> 2.17.1
>