| Message ID | 1395922988-37702-4-git-send-email-paul.durrant@citrix.com |
|---|---|
| State | Superseded, archived |
| Delegated to: | David Miller |
| Headers | show |
On Thu, 2014-03-27 at 12:23 +0000, Paul Durrant wrote: > The BUG_ON to catch ring overflow in xenvif_rx_action() makes the assumption > that meta_slots_used == ring slots used. This is not the case for GSO > packets. Can you explain why not here please. > This patch changes the test to actually check ring slots. > > Signed-off-by: Paul Durrant <paul.durrant@citrix.com> > Cc: Ian Campbell <ian.campbell@citrix.com> > Cc: Wei Liu <wei.liu2@citrix.com> > Cc: Sander Eikelenboom <linux@eikelenboom.it> > --- > drivers/net/xen-netback/netback.c | 8 +++++++- > 1 file changed, 7 insertions(+), 1 deletion(-) > > diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c > index ac35489..ae7351f 100644 > --- a/drivers/net/xen-netback/netback.c > +++ b/drivers/net/xen-netback/netback.c > @@ -481,6 +481,8 @@ static void xenvif_rx_action(struct xenvif *vif) > > while ((skb = skb_dequeue(&vif->rx_queue)) != NULL) { > RING_IDX max_slots_needed; > + RING_IDX old_req_cons; > + RING_IDX ring_slots_used; > int i; > > /* We need a cheap worse case estimate for the number of > @@ -520,8 +522,12 @@ static void xenvif_rx_action(struct xenvif *vif) > vif->rx_last_skb_slots = 0; > > sco = (struct skb_cb_overlay *)skb->cb; > + > + old_req_cons = vif->rx.req_cons; > sco->meta_slots_used = xenvif_gop_skb(skb, &npo); > - BUG_ON(sco->meta_slots_used > max_slots_needed); > + ring_slots_used = vif->rx.req_cons - old_req_cons; > + > + BUG_ON(ring_slots_used > max_slots_needed); > > __skb_queue_tail(&rxq, skb); > } -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
> -----Original Message----- > From: Ian Campbell > Sent: 27 March 2014 12:28 > To: Paul Durrant > Cc: xen-devel@lists.xen.org; netdev@vger.kernel.org; Wei Liu; Sander > Eikelenboom > Subject: Re: [PATCH net 3/3] xen-netback: BUG_ON in xenvif_rx_action() > not catching overflow > > On Thu, 2014-03-27 at 12:23 +0000, Paul Durrant wrote: > > The BUG_ON to catch ring overflow in xenvif_rx_action() makes the > assumption > > that meta_slots_used == ring slots used. This is not the case for GSO > > packets. > > Can you explain why not here please. > Sure. I'll add an explanation. Paul > > This patch changes the test to actually check ring slots. > > > > Signed-off-by: Paul Durrant <paul.durrant@citrix.com> > > Cc: Ian Campbell <ian.campbell@citrix.com> > > Cc: Wei Liu <wei.liu2@citrix.com> > > Cc: Sander Eikelenboom <linux@eikelenboom.it> > > --- > > drivers/net/xen-netback/netback.c | 8 +++++++- > > 1 file changed, 7 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen- > netback/netback.c > > index ac35489..ae7351f 100644 > > --- a/drivers/net/xen-netback/netback.c > > +++ b/drivers/net/xen-netback/netback.c > > @@ -481,6 +481,8 @@ static void xenvif_rx_action(struct xenvif *vif) > > > > while ((skb = skb_dequeue(&vif->rx_queue)) != NULL) { > > RING_IDX max_slots_needed; > > + RING_IDX old_req_cons; > > + RING_IDX ring_slots_used; > > int i; > > > > /* We need a cheap worse case estimate for the number of > > @@ -520,8 +522,12 @@ static void xenvif_rx_action(struct xenvif *vif) > > vif->rx_last_skb_slots = 0; > > > > sco = (struct skb_cb_overlay *)skb->cb; > > + > > + old_req_cons = vif->rx.req_cons; > > sco->meta_slots_used = xenvif_gop_skb(skb, &npo); > > - BUG_ON(sco->meta_slots_used > max_slots_needed); > > + ring_slots_used = vif->rx.req_cons - old_req_cons; > > + > > + BUG_ON(ring_slots_used > max_slots_needed); > > > > __skb_queue_tail(&rxq, skb); > > } >
diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c index ac35489..ae7351f 100644 --- a/drivers/net/xen-netback/netback.c +++ b/drivers/net/xen-netback/netback.c @@ -481,6 +481,8 @@ static void xenvif_rx_action(struct xenvif *vif) while ((skb = skb_dequeue(&vif->rx_queue)) != NULL) { RING_IDX max_slots_needed; + RING_IDX old_req_cons; + RING_IDX ring_slots_used; int i; /* We need a cheap worse case estimate for the number of @@ -520,8 +522,12 @@ static void xenvif_rx_action(struct xenvif *vif) vif->rx_last_skb_slots = 0; sco = (struct skb_cb_overlay *)skb->cb; + + old_req_cons = vif->rx.req_cons; sco->meta_slots_used = xenvif_gop_skb(skb, &npo); - BUG_ON(sco->meta_slots_used > max_slots_needed); + ring_slots_used = vif->rx.req_cons - old_req_cons; + + BUG_ON(ring_slots_used > max_slots_needed); __skb_queue_tail(&rxq, skb); }
The BUG_ON to catch ring overflow in xenvif_rx_action() makes the assumption that meta_slots_used == ring slots used. This is not the case for GSO packets. This patch changes the test to actually check ring slots. Signed-off-by: Paul Durrant <paul.durrant@citrix.com> Cc: Ian Campbell <ian.campbell@citrix.com> Cc: Wei Liu <wei.liu2@citrix.com> Cc: Sander Eikelenboom <linux@eikelenboom.it> --- drivers/net/xen-netback/netback.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)