linux-kernel - Re: [PATCH 2/4] iommu: Consolitate ->add/remove

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Message-ID: <3ca13757-edf8-95cb-6316-73d202f97dbf@arm.com>
Date:   Wed, 5 Dec 2018 18:20:50 +0000
From:   Robin Murphy <robin.murphy@....com>
To:     Joerg Roedel <joro@...tes.org>, iommu@...ts.linux-foundation.org
Cc:     linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
        Joerg Roedel <jroedel@...e.de>
Subject: Re: [PATCH 2/4] iommu: Consolitate ->add/remove_device() calls

On 05/12/2018 14:36, Joerg Roedel wrote:
> From: Joerg Roedel <jroedel@...e.de>
> 
> Put them into separate functions and call those where the
> plain ops have been called before.
> 
> Signed-off-by: Joerg Roedel <jroedel@...e.de>
> ---
>   drivers/iommu/iommu.c | 54 ++++++++++++++++++++++---------------------
>   include/linux/iommu.h |  3 +++
>   2 files changed, 31 insertions(+), 26 deletions(-)
> 
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index edbdf5d6962c..ad4dc51eb69c 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -110,6 +110,26 @@ void iommu_device_unregister(struct iommu_device *iommu)
>   	spin_unlock(&iommu_device_lock);
>   }
>   
> +int iommu_probe_device(struct device *dev)
> +{
> +	const struct iommu_ops *ops = dev->bus->iommu_ops;
> +
> +	if (!ops->add_device)
> +		return 0;

Is there any good reason to let .add_device/.remove_device be optional 
still? Everyone's implemented them for a while now, and on a practical 
level I don't really see how else we could expect devices to be taken in 
and out of their appropriate groups correctly.

Robin.

> +
> +	WARN_ON(dev->iommu_group);
> +
> +	return ops->add_device(dev);
> +}
> +
> +void  iommu_release_device(struct device *dev)
> +{
> +	const struct iommu_ops *ops = dev->bus->iommu_ops;
> +
> +	if (ops->remove_device && dev->iommu_group)
> +		ops->remove_device(dev);
> +}
> +
>   static struct iommu_domain *__iommu_domain_alloc(struct bus_type *bus,
>   						 unsigned type);
>   static int __iommu_attach_device(struct iommu_domain *domain,
> @@ -1117,16 +1137,7 @@ struct iommu_domain *iommu_group_default_domain(struct iommu_group *group)
>   
>   static int add_iommu_group(struct device *dev, void *data)
>   {
> -	struct iommu_callback_data *cb = data;
> -	const struct iommu_ops *ops = cb->ops;
> -	int ret;
> -
> -	if (!ops->add_device)
> -		return 0;
> -
> -	WARN_ON(dev->iommu_group);
> -
> -	ret = ops->add_device(dev);
> +	int ret = iommu_probe_device(dev);
>   
>   	/*
>   	 * We ignore -ENODEV errors for now, as they just mean that the
> @@ -1141,11 +1152,7 @@ static int add_iommu_group(struct device *dev, void *data)
>   
>   static int remove_iommu_group(struct device *dev, void *data)
>   {
> -	struct iommu_callback_data *cb = data;
> -	const struct iommu_ops *ops = cb->ops;
> -
> -	if (ops->remove_device && dev->iommu_group)
> -		ops->remove_device(dev);
> +	iommu_release_device(dev);
>   
>   	return 0;
>   }
> @@ -1153,27 +1160,22 @@ static int remove_iommu_group(struct device *dev, void *data)
>   static int iommu_bus_notifier(struct notifier_block *nb,
>   			      unsigned long action, void *data)
>   {
> +	unsigned long group_action = 0;
>   	struct device *dev = data;
> -	const struct iommu_ops *ops = dev->bus->iommu_ops;
>   	struct iommu_group *group;
> -	unsigned long group_action = 0;
>   
>   	/*
>   	 * ADD/DEL call into iommu driver ops if provided, which may
>   	 * result in ADD/DEL notifiers to group->notifier
>   	 */
>   	if (action == BUS_NOTIFY_ADD_DEVICE) {
> -		if (ops->add_device) {
> -			int ret;
> +		int ret;
>   
> -			ret = ops->add_device(dev);
> -			return (ret) ? NOTIFY_DONE : NOTIFY_OK;
> -		}
> +		ret = iommu_probe_device(dev);
> +		return (ret) ? NOTIFY_DONE : NOTIFY_OK;
>   	} else if (action == BUS_NOTIFY_REMOVED_DEVICE) {
> -		if (ops->remove_device && dev->iommu_group) {
> -			ops->remove_device(dev);
> -			return 0;
> -		}
> +		iommu_release_device(dev);
> +		return NOTIFY_OK;
>   	}
>   
>   	/*
> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> index a1d28f42cb77..2357841845bb 100644
> --- a/include/linux/iommu.h
> +++ b/include/linux/iommu.h
> @@ -398,6 +398,9 @@ void iommu_fwspec_free(struct device *dev);
>   int iommu_fwspec_add_ids(struct device *dev, u32 *ids, int num_ids);
>   const struct iommu_ops *iommu_ops_from_fwnode(struct fwnode_handle *fwnode);
>   
> +int iommu_probe_device(struct device *dev);
> +void  iommu_release_device(struct device *dev);
> +
>   #else /* CONFIG_IOMMU_API */
>   
>   struct iommu_ops {};
>