netdev - Re: [PATCH 3/5] NET: IPV4: ARP: allow to invalidate specific ARP entries

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Date:	Fri, 07 Jan 2011 15:15:43 +0200
From:	Maxim Levitsky <maximlevitsky@...il.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	linux1394-devel <linux1394-devel@...ts.sourceforge.net>,
	Stefan Richter <stefanr@...6.in-berlin.de>,
	netdev@...r.kernel.org, "David S. Miller" <davem@...emloft.net>,
	Alexey Kuznetsov <kuznet@....inr.ac.ru>,
	James Morris <jmorris@...ei.org>,
	Patrick McHardy <kaber@...sh.net>
Subject: Re: [PATCH 3/5] NET: IPV4: ARP: allow to invalidate specific ARP
 entries

On Fri, 2011-01-07 at 13:57 +0100, Eric Dumazet wrote:
> Le vendredi 07 janvier 2011 à 14:47 +0200, Maxim Levitsky a écrit :
> > On Mon, 2010-11-29 at 04:09 +0200, Maxim Levitsky wrote:
> > > IPv4 over firewire needs to be able to remove ARP entries
> > > from the ARP cache that belong to nodes that are removed, because
> > > IPv4 over firewire uses ARP packets for private information
> > > about nodes.
> > > 
> > > This information becomes invalid as soon as node drops
> > > off the bus and when it reconnects, its only possible
> > > to start takling to is after it responded to an ARP packet.
> > > But ARP cache prevents such packets from being sent.
> > > 
> > > CC: netdev@...r.kernel.org
> > > CC: "David S. Miller" <davem@...emloft.net>
> > > CC: Alexey Kuznetsov <kuznet@....inr.ac.ru>
> > > CC: James Morris <jmorris@...ei.org>
> > > CC: Patrick McHardy <kaber@...sh.net>
> > 
> > Anybody?
> > 
> > Best regards,
> > 	Maxim Levitsky
> > 
> > > 
> > > 
> > > Signed-off-by: Maxim Levitsky <maximlevitsky@...il.com>
> > > ---
> > >  include/net/arp.h |    1 +
> > >  net/ipv4/arp.c    |   29 ++++++++++++++++++-----------
> > >  2 files changed, 19 insertions(+), 11 deletions(-)
> > > 
> > > diff --git a/include/net/arp.h b/include/net/arp.h
> > > index f4cf6ce..91f0568 100644
> > > --- a/include/net/arp.h
> > > +++ b/include/net/arp.h
> > > @@ -25,5 +25,6 @@ extern struct sk_buff *arp_create(int type, int ptype, __be32 dest_ip,
> > >  				  const unsigned char *src_hw,
> > >  				  const unsigned char *target_hw);
> > >  extern void arp_xmit(struct sk_buff *skb);
> > > +int arp_invalidate(struct net_device *dev, __be32 ip);
> > >  
> > >  #endif	/* _ARP_H */
> > > diff --git a/net/ipv4/arp.c b/net/ipv4/arp.c
> > > index d8e540c..35b1272 100644
> > > --- a/net/ipv4/arp.c
> > > +++ b/net/ipv4/arp.c
> > > @@ -1142,6 +1142,23 @@ static int arp_req_get(struct arpreq *r, struct net_device *dev)
> > >  	return err;
> > >  }
> > >  
> > > +int arp_invalidate(struct net_device *dev, __be32 ip)
> > > +{
> > > +	int err = -ENXIO;
> > > +	struct neighbour *neigh = neigh_lookup(&arp_tbl, &ip, dev);
> > > +
> > > +	if (neigh) {
> > > +		if (neigh->nud_state & ~NUD_NOARP)
> > > +			err = neigh_update(neigh, NULL, NUD_FAILED,
> > > +					   NEIGH_UPDATE_F_OVERRIDE|
> > > +					   NEIGH_UPDATE_F_ADMIN);
> > > +		neigh_release(neigh);
> > > +	}
> > > +
> > > +	return err;
> > > +}
> > > +EXPORT_SYMBOL(arp_invalidate);
> > > +
> > >  static int arp_req_delete_public(struct net *net, struct arpreq *r,
> > >  		struct net_device *dev)
> > >  {
> > > @@ -1162,7 +1179,6 @@ static int arp_req_delete(struct net *net, struct arpreq *r,
> > >  {
> > >  	int err;
> > >  	__be32 ip;
> > > -	struct neighbour *neigh;
> > >  
> > >  	if (r->arp_flags & ATF_PUBL)
> > >  		return arp_req_delete_public(net, r, dev);
> > > @@ -1180,16 +1196,7 @@ static int arp_req_delete(struct net *net, struct arpreq *r,
> > >  		if (!dev)
> > >  			return -EINVAL;
> > >  	}
> > > -	err = -ENXIO;
> > > -	neigh = neigh_lookup(&arp_tbl, &ip, dev);
> > > -	if (neigh) {
> > > -		if (neigh->nud_state & ~NUD_NOARP)
> > > -			err = neigh_update(neigh, NULL, NUD_FAILED,
> > > -					   NEIGH_UPDATE_F_OVERRIDE|
> > > -					   NEIGH_UPDATE_F_ADMIN);
> > > -		neigh_release(neigh);
> > > -	}
> > > -	return err;
> > > +	return arp_invalidate(dev, ip);
> > >  }
> > >  
> > >  /*
> > 
> 
> Hi Maxim
> 
> You were supposed to respin your patch after my commit :
> 
> (941666c2e3e0f9f6a1 net: RCU conversion of dev_getbyhwaddr() and
> arp_ioctl())
> 
> Thanks


Will do very soon.

Best regards,
	Maxim Levitsky

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