From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: Re: [PATCH RFC 5/6] net: orphan frags on receive Date: Wed, 9 May 2012 18:12:02 +0300 Message-ID: <20120509151202.GB20474@redhat.com> References: <1336571692.25514.122.camel@zakaz.uk.xensource.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: David Miller , "netdev@vger.kernel.org" , "eric.dumazet@gmail.com" To: Ian Campbell Return-path: Received: from mx1.redhat.com ([209.132.183.28]:32653 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759850Ab2EIPMB (ORCPT ); Wed, 9 May 2012 11:12:01 -0400 Content-Disposition: inline In-Reply-To: <1336571692.25514.122.camel@zakaz.uk.xensource.com> Sender: netdev-owner@vger.kernel.org List-ID: On Wed, May 09, 2012 at 02:54:52PM +0100, Ian Campbell wrote: > On Mon, 2012-05-07 at 14:54 +0100, Michael S. Tsirkin wrote: > > zero copy packets are normally sent to the outside > > network, but bridging, tun etc might loop them > > back to host networking stack. If this happens > > destructors will never be called, so orphan > > the frags immediately on receive. > > I think this deceptively simply patch is actually the meat of the > series. > It's been a long time since I dug into the bridging code. Am I right > that this function is only reached when an SKB is going to be delivered > locally and not when forwarding to another port on the bridge? > > Ian. I think so - bridge uses netdev_rx_handler_unregister so it does not go through packet handlers. > > > > Signed-off-by: Michael S. Tsirkin > > --- > > net/core/dev.c | 2 ++ > > 1 files changed, 2 insertions(+), 0 deletions(-) > > > > diff --git a/net/core/dev.c b/net/core/dev.c > > index a2be59f..c0cdc00 100644 > > --- a/net/core/dev.c > > +++ b/net/core/dev.c > > @@ -1630,6 +1630,8 @@ static inline int deliver_skb(struct sk_buff *skb, > > struct packet_type *pt_prev, > > struct net_device *orig_dev) > > { > > + if (unlikely(skb_orphan_frags(skb, GFP_ATOMIC))) > > + return -ENOMEM; > > atomic_inc(&skb->users); > > return pt_prev->func(skb, skb->dev, pt_prev, orig_dev); > > } >