On Tue, 2006-07-25 at 17:39 +1000, Herbert Xu wrote:
> Steve Wise <[EMAIL PROTECTED]> wrote:
> >
> > Routing redirect events are broadcast as a pair of rtmsgs, RTM_DELROUTE
> > and RTM_NEWROUTE.
>
> This may confuse existing rtnetlink users since you're generating an
> RTM_DELROUTE message that's identical to one triggered by something
> like 'ip route del'.
>
Yea, I didn't really want to create a REDIRECT rtmsg, so I punted. :-)
But they really are seeing a delete followed by an add. That's what the
kernel is doing.
> As you're introducing a completely new RTM_ROUTEUPD type, it might
> be better to attach any information from the existing route that you
> need to the ROUTEUPD message.
Yea, the main change is the next hop ip address or gateway field.
>
> Actually, what was the reason you need the existing route here?
>
The rdma driver needs to update all established rdma connections that
are using the next-hop information of the existing route and make them
use the next-hop information of the new route. In addition, the rdma
driver might have a reference to the old dst entry. So it can release
that ref and add a ref to the new dst entry.
> > diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
> > index 5f87533..33d8a83 100644
> > --- a/net/ipv4/fib_semantics.c
> > +++ b/net/ipv4/fib_semantics.c
> > @@ -44,6 +44,7 @@ #include <net/tcp.h>
> > #include <net/sock.h>
> > #include <net/ip_fib.h>
> > #include <net/ip_mp_alg.h>
> > +#include <net/netevent.h>
> >
> > #include "fib_lookup.h"
> >
> > @@ -279,6 +280,14 @@ void rtmsg_fib(int event, u32 key, struc
> > struct sk_buff *skb;
> > u32 pid = req ? req->pid : n->nlmsg_pid;
> > int size = NLMSG_SPACE(sizeof(struct rtmsg)+256);
> > + struct netevent_route_info nri;
> > + int netevent;
> > +
> > + nri.family = AF_INET;
> > + nri.data = &fa->fa_info;
> > + netevent = event == RTM_NEWROUTE ? NETEVENT_ROUTE_ADD
> > + : NETEVENT_ROUTE_DEL;
> > + call_netevent_notifiers(netevent, &nri);
>
> Hmm, this is broken. These route events are meaningless without the
> corresponding IP rule events. Are you sure you really want to make
> your hardware/driver grok multiple routing tables?
>
> Perhaps you should simply stick to dst entries and flush all your
> tables when the routes are changed. This is what the Linux IP stack
> does.
>
I have to admit I'm a little fuzzy on the routing stuff. The main
netevents I've utilized in the the rdma driver I'm writing is the
neighbour update event and the redirect event. Route add/del was added
for completeness of "routing" netevents.
Can you expand further or point me to code where the IP stack "flushes
its tables" when routes are changed?
>From my experience, all the rdma driver needs is the dst entry. It
using the routing table to determine the dst_entry at connection
establish time. And it needs to know if the next-hop or PMTU ever
changes.
> > diff --git a/net/ipv4/route.c b/net/ipv4/route.c
> > index 2dc6dbb..18879e6 100644
> > --- a/net/ipv4/route.c
> > +++ b/net/ipv4/route.c
> > @@ -1117,6 +1120,52 @@ static void rt_del(unsigned hash, struct
> > spin_unlock_bh(rt_hash_lock_addr(hash));
> > }
> >
> > +static void rtm_redirect(struct rtable *old, struct rtable *new)
> > +{
> > + struct netevent_redirect netevent;
> > + struct sk_buff *skb;
> > + int err;
> > +
> > + netevent.old = &old->u.dst;
> > + netevent.new = &new->u.dst;
> > +
> > + /* notify netevent subscribers */
> > + call_netevent_notifiers(NETEVENT_REDIRECT, &netevent);
> > +
> > + /* Post NETLINK messages: RTM_DELROUTE for old route,
> > + RTM_NEWROUTE for new route */
> > + skb = alloc_skb(NLMSG_GOODSIZE, GFP_ATOMIC);
>
> Please use a better size estimate rather than NLMSG_GOODSIZE here since
> you're doing GFP_ATOMIC.
>
ok
> > @@ -1442,6 +1493,32 @@ unsigned short ip_rt_frag_needed(struct
> > return est_mtu ? : new_mtu;
> > }
> >
> > +static void rtm_pmtu_update(struct rtable *rt)
> > +{
> > + struct sk_buff *skb;
> > + int err;
> > +
> > + call_netevent_notifiers(NETEVENT_PMTU_UPDATE, &rt->u.dst);
> > +
> > + skb = alloc_skb(NLMSG_GOODSIZE, GFP_ATOMIC);
>
> Ditto.
>
ok
Thanks,
Steve.
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