Subject: Re: [PATCH RFC 2/5] vringfd base/offset

From: Anthony Liguori <[email-masked]>
Date: Sat, 05 Apr 2008 12:18:59 -0500

Rusty Russell wrote:
> It turns out the lguest (and possibly kvm) want the addresses in the
> ring buffer to only cover a certain part of memory, and be offset.
> 
> It makes sense that this be an ioctl.
> 
> Signed-off-by: Rusty Russell <[email-masked]>
>

<snip>

> @@ -208,12 +232,15 @@ int vring_get_buffer(struct vring_info *
>  		out_len = &dummy;
>  
>  	*in_len = *out_len = 0;
> -	
> -	if (unlikely(get_user(head, &vr->ring.avail->ring[head]) != 0))
> +
> +	if (unlikely(get_user(head, &vr->ring.avail->ring[vr->last_avail
> +							  % vr->ring.num])))

Why not & with vr->mask for the sake of consistency with the rest of the 
code.

Regards,

Anthony Liguori