linux-kernel - Re: [PATCH v11 10/12] vduse: merge tree search logic of IOTLB_GET_FD and IOTLB_GET

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Message-ID: <20260110185423-mutt-send-email-mst@kernel.org>
Date: Sat, 10 Jan 2026 18:56:35 -0500
From: "Michael S. Tsirkin" <mst@...hat.com>
To: Eugenio Pérez <eperezma@...hat.com>
Cc: linux-kernel@...r.kernel.org, virtualization@...ts.linux.dev,
	Maxime Coquelin <mcoqueli@...hat.com>,
	Laurent Vivier <lvivier@...hat.com>, Cindy Lu <lulu@...hat.com>,
	jasowang@...hat.com, Xuan Zhuo <xuanzhuo@...ux.alibaba.com>,
	Stefano Garzarella <sgarzare@...hat.com>,
	Yongji Xie <xieyongji@...edance.com>
Subject: Re: [PATCH v11 10/12] vduse: merge tree search logic of IOTLB_GET_FD
 and IOTLB_GET_INFO ioctls

On Fri, Jan 09, 2026 at 04:24:28PM +0100, Eugenio Pérez wrote:
> The next patch adds new ioctl with the ASID member per entry.  Abstract
> these two so it can be build on top easily.
> 
> Signed-off-by: Eugenio Pérez <eperezma@...hat.com>
> ---
> v11: New in v11
> ---
>  drivers/vdpa/vdpa_user/vduse_dev.c | 101 ++++++++++++++++-------------
>  1 file changed, 55 insertions(+), 46 deletions(-)
> 
> diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c
> index 675da1465e0e..bf437816fd7d 100644
> --- a/drivers/vdpa/vdpa_user/vduse_dev.c
> +++ b/drivers/vdpa/vdpa_user/vduse_dev.c
> @@ -1247,6 +1247,50 @@ static void vduse_vq_update_effective_cpu(struct vduse_virtqueue *vq)
>  	vq->irq_effective_cpu = curr_cpu;
>  }
>  
> +static int vduse_dev_iotlb_entry(struct vduse_dev *dev,
> +				 struct vduse_iotlb_entry *entry,
> +				 struct file **f, uint64_t *capability)
> +{
> +	int r = -EINVAL;
> +	struct vhost_iotlb_map *map;
> +	const struct vdpa_map_file *map_file;
> +
> +	if (entry->start > entry->last)
> +		return -EINVAL;
> +
> +	mutex_lock(&dev->domain_lock);
> +	if (!dev->domain)
> +		goto out;
> +
> +	spin_lock(&dev->domain->iotlb_lock);
> +	map = vhost_iotlb_itree_first(dev->domain->iotlb, entry->start,
> +				      entry->last);
> +	if (map) {
> +		if (f) {
> +			map_file = (struct vdpa_map_file *)map->opaque;

map_file assigned value when f != NULL here ...

> +			*f = get_file(map_file->file);
> +		}
> +		entry->offset = map_file->offset;

but dereferenced unconditionally here.

> +		entry->start = map->start;
> +		entry->last = map->last;
> +		entry->perm = map->perm;
> +		if (capability) {
> +			*capability = 0;
> +
> +			if (dev->domain->bounce_map && map->start == 0 &&
> +			    map->last == dev->domain->bounce_size - 1)
> +				*capability |= VDUSE_IOVA_CAP_UMEM;
> +		}
> +
> +		r = 0;
> +	}
> +	spin_unlock(&dev->domain->iotlb_lock);
> +
> +out:
> +	mutex_unlock(&dev->domain_lock);
> +	return r;
> +}
> +
>  static long vduse_dev_ioctl(struct file *file, unsigned int cmd,
>  			    unsigned long arg)
>  {