Re: [Xen-users] kernel 3.9.2 - xen 4.2.2/4.3rc1 => BUG unable to handle kernel paging request netif_poll+0x49c/0xe8

[Wei Liu <wei.liu2@citrix.com>]

On Fri, May 31, 2013 at 05:00:32PM +0100, Jan Beulich wrote:
> >>> On 31.05.13 at 17:47, Wei Liu <wei.liu2@citrix.com> wrote:
> > --- a/drivers/xen/netfront/netfront.c
> > +++ b/drivers/xen/netfront/netfront.c
> > @@ -1319,6 +1319,7 @@ static RING_IDX xennet_fill_frags(struct netfront_info *np,
> >  		kfree_skb(nskb);
> >  
> >  		nr_frags++;
> > +		BUG_ON(nr_frags >= MAX_SKB_FRAGS);
> 
> Isn't this going to see false positives? I would have thought such a
> check would need to go at the top of the loop body.
> 
> Jan
> 

Ha, yes.

Please use this one.


Wei.

-----
diff --git a/drivers/xen/netfront/netfront.c b/drivers/xen/netfront/netfront.c
index 6e5d233..9583011 100644
--- a/drivers/xen/netfront/netfront.c
+++ b/drivers/xen/netfront/netfront.c
@@ -1306,6 +1306,7 @@ static RING_IDX xennet_fill_frags(struct netfront_info *np,
 	struct sk_buff *nskb;
 
 	while ((nskb = __skb_dequeue(list))) {
+		BUG_ON(nr_frags >= MAX_SKB_FRAGS);
 		struct netif_rx_response *rx =
 			RING_GET_RESPONSE(&np->rx, ++cons);