Re: [RFC 3/4] vduse: grab the module's references until there is no vduse device

["Michael S. Tsirkin" <mst@redhat.com>]

On Mon, Oct 19, 2020 at 10:56:22PM +0800, Xie Yongji wrote:
> The module should not be unloaded if any vduse device exists.
> So increase the module's reference count when creating vduse
> device. And the reference count is kept until the device is
> destroyed.
> 
> Signed-off-by: Xie Yongji <xieyongji@bytedance.com>
> ---
>  drivers/vdpa/vdpa_user/vduse_dev.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c
> index 6787ba66725c..f04aa02de8c1 100644
> --- a/drivers/vdpa/vdpa_user/vduse_dev.c
> +++ b/drivers/vdpa/vdpa_user/vduse_dev.c
> @@ -887,6 +887,7 @@ static int vduse_destroy_dev(u32 id)
>  	kfree(dev->vqs);
>  	vduse_iova_domain_destroy(dev->domain);
>  	vduse_dev_destroy(dev);
> +	module_put(THIS_MODULE);
>  
>  	return 0;
>  }
> @@ -931,6 +932,7 @@ static int vduse_create_dev(struct vduse_dev_config *config)
>  
>  	dev->connected = true;
>  	list_add(&dev->list, &vduse_devs);
> +	__module_get(THIS_MODULE);
>  
>  	return fd;
>  err_fd:

This kind of thing is usually an indicator of a bug. E.g.
if the refcount drops to 0 on module_put(THIS_MODULE) it
will be unloaded and the following return will not run.



> -- 
> 2.25.1