Re: [PATCH v7 1/3] tcm_vhost: Introduce tcm_vhost_check_feature()

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

On Thu, Apr 18, 2013 at 09:05:52AM +0800, Asias He wrote:
> This helper is useful to check if a feature is supported.
> 
> Signed-off-by: Asias He <asias@redhat.com>
> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>

Why do we need the locking here by the way?
It seems features don't change while vhost
is running.

> ---
>  drivers/vhost/tcm_vhost.c | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 
> diff --git a/drivers/vhost/tcm_vhost.c b/drivers/vhost/tcm_vhost.c
> index 957a0b9..88ebb79 100644
> --- a/drivers/vhost/tcm_vhost.c
> +++ b/drivers/vhost/tcm_vhost.c
> @@ -99,6 +99,18 @@ static int iov_num_pages(struct iovec *iov)
>  	       ((unsigned long)iov->iov_base & PAGE_MASK)) >> PAGE_SHIFT;
>  }
>  
> +static bool tcm_vhost_check_feature(struct vhost_scsi *vs, int feature)
> +{
> +	bool ret = false;
> +
> +	mutex_lock(&vs->dev.mutex);
> +	if (vhost_has_feature(&vs->dev, feature))
> +		ret = true;
> +	mutex_unlock(&vs->dev.mutex);
> +
> +	return ret;
> +}
> +
>  static int tcm_vhost_check_true(struct se_portal_group *se_tpg)
>  {
>  	return 1;
> -- 
> 1.8.1.4