RE: [PATCH 06/10] vfio: Remove vfio_external_group_match_file()

["Tian, Kevin" <kevin.tian@intel.com>]

> From: Jason Gunthorpe <jgg@nvidia.com>
> Sent: Friday, April 15, 2022 2:46 AM
> 
> vfio_group_fops_open() ensures there is only ever one struct file open for
> any struct vfio_group at any time:
> 
> 	/* Do we need multiple instances of the group open?  Seems not. */
> 	opened = atomic_cmpxchg(&group->opened, 0, 1);
> 	if (opened) {
> 		vfio_group_put(group);
> 		return -EBUSY;
> 
> Therefor the struct file * can be used directly to search the list of VFIO
> groups that KVM keeps instead of using the
> vfio_external_group_match_file() callback to try to figure out if the
> passed in FD matches the list or not.
> 
> Delete vfio_external_group_match_file().
> 
> Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

Reviewed-by: Kevin Tian <kevin.tian@intel.com>

> ---
>  drivers/vfio/vfio.c  |  9 ---------
>  include/linux/vfio.h |  2 --
>  virt/kvm/vfio.c      | 19 +------------------
>  3 files changed, 1 insertion(+), 29 deletions(-)
> 
> diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
> index 4d62de69705573..eb65b4c80ece64 100644
> --- a/drivers/vfio/vfio.c
> +++ b/drivers/vfio/vfio.c
> @@ -1989,15 +1989,6 @@ void vfio_group_put_external_user(struct
> vfio_group *group)
>  }
>  EXPORT_SYMBOL_GPL(vfio_group_put_external_user);
> 
> -bool vfio_external_group_match_file(struct vfio_group *test_group,
> -				    struct file *filep)
> -{
> -	struct vfio_group *group = filep->private_data;
> -
> -	return (filep->f_op == &vfio_group_fops) && (group == test_group);
> -}
> -EXPORT_SYMBOL_GPL(vfio_external_group_match_file);
> -
>  /**
>   * vfio_file_iommu_group - Return the struct iommu_group for the vfio file
>   * @filep: VFIO file
> diff --git a/include/linux/vfio.h b/include/linux/vfio.h
> index e5ca7d5a0f1584..d09a1856d4e5ea 100644
> --- a/include/linux/vfio.h
> +++ b/include/linux/vfio.h
> @@ -145,8 +145,6 @@ extern struct vfio_group
> *vfio_group_get_external_user(struct file *filep);
>  extern void vfio_group_put_external_user(struct vfio_group *group);
>  extern struct vfio_group *vfio_group_get_external_user_from_dev(struct
> device
>  								*dev);
> -extern bool vfio_external_group_match_file(struct vfio_group *group,
> -					   struct file *filep);
>  extern long vfio_external_check_extension(struct vfio_group *group,
>  					  unsigned long arg);
>  const struct vfio_file_ops *vfio_file_get_ops(struct file *filep);
> diff --git a/virt/kvm/vfio.c b/virt/kvm/vfio.c
> index 743e4870fa1825..955cabc0683b29 100644
> --- a/virt/kvm/vfio.c
> +++ b/virt/kvm/vfio.c
> @@ -60,22 +60,6 @@ static struct vfio_group
> *kvm_vfio_group_get_external_user(struct file *filep)
>  	return vfio_group;
>  }
> 
> -static bool kvm_vfio_external_group_match_file(struct vfio_group *group,
> -					       struct file *filep)
> -{
> -	bool ret, (*fn)(struct vfio_group *, struct file *);
> -
> -	fn = symbol_get(vfio_external_group_match_file);
> -	if (!fn)
> -		return false;
> -
> -	ret = fn(group, filep);
> -
> -	symbol_put(vfio_external_group_match_file);
> -
> -	return ret;
> -}
> -
>  static void kvm_vfio_group_put_external_user(struct vfio_group
> *vfio_group)
>  {
>  	void (*fn)(struct vfio_group *);
> @@ -244,8 +228,7 @@ static int kvm_vfio_group_del(struct kvm_device
> *dev, unsigned int fd)
>  	mutex_lock(&kv->lock);
> 
>  	list_for_each_entry(kvg, &kv->group_list, node) {
> -		if (!kvm_vfio_external_group_match_file(kvg->vfio_group,
> -							f.file))
> +		if (kvg->filp != f.file)
>  			continue;
> 
>  		list_del(&kvg->node);
> --
> 2.35.1