netdev - Re: [PATCH 08/12] vfio: use __anon_inode

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Date:   Fri, 8 May 2020 09:55:07 -0600
From:   Alex Williamson <alex.williamson@...hat.com>
To:     Christoph Hellwig <hch@....de>
Cc:     Alexander Viro <viro@...iv.linux.org.uk>,
        linux-integrity@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-gpio@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        linux-rdma@...r.kernel.org, kvm@...r.kernel.org,
        linux-fsdevel@...r.kernel.org, io-uring@...r.kernel.org,
        netdev@...r.kernel.org, bpf@...r.kernel.org
Subject: Re: [PATCH 08/12] vfio: use __anon_inode_getfd

On Fri,  8 May 2020 17:36:30 +0200
Christoph Hellwig <hch@....de> wrote:

> Use __anon_inode_getfd instead of opencoding the logic using
> get_unused_fd_flags + anon_inode_getfile.
> 
> Signed-off-by: Christoph Hellwig <hch@....de>
> ---
>  drivers/vfio/vfio.c | 37 ++++++++-----------------------------
>  1 file changed, 8 insertions(+), 29 deletions(-)


Thanks!

Acked-by: Alex Williamson <alex.williamson@...hat.com>

> diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
> index 765e0e5d83ed9..33a88103f857f 100644
> --- a/drivers/vfio/vfio.c
> +++ b/drivers/vfio/vfio.c
> @@ -1451,42 +1451,21 @@ static int vfio_group_get_device_fd(struct vfio_group *group, char *buf)
>  		return ret;
>  	}
>  
> -	/*
> -	 * We can't use anon_inode_getfd() because we need to modify
> -	 * the f_mode flags directly to allow more than just ioctls
> -	 */
> -	ret = get_unused_fd_flags(O_CLOEXEC);
> -	if (ret < 0) {
> -		device->ops->release(device->device_data);
> -		vfio_device_put(device);
> -		return ret;
> -	}
> -
> -	filep = anon_inode_getfile("[vfio-device]", &vfio_device_fops,
> -				   device, O_RDWR);
> -	if (IS_ERR(filep)) {
> -		put_unused_fd(ret);
> -		ret = PTR_ERR(filep);
> -		device->ops->release(device->device_data);
> -		vfio_device_put(device);
> -		return ret;
> -	}
> -
> -	/*
> -	 * TODO: add an anon_inode interface to do this.
> -	 * Appears to be missing by lack of need rather than
> -	 * explicitly prevented.  Now there's need.
> -	 */
> +	ret = __anon_inode_getfd("[vfio-device]", &vfio_device_fops,
> +				   device, O_CLOEXEC | O_RDWR, &filep);
> +	if (ret < 0)
> +		goto release;
>  	filep->f_mode |= (FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE);
> -
>  	atomic_inc(&group->container_users);
> -
>  	fd_install(ret, filep);
>  
>  	if (group->noiommu)
>  		dev_warn(device->dev, "vfio-noiommu device opened by user "
>  			 "(%s:%d)\n", current->comm, task_pid_nr(current));
> -
> +	return ret;
> +release:
> +	device->ops->release(device->device_data);
> +	vfio_device_put(device);
>  	return ret;
>  }
>