On Fri, May 04, 2007 at 02:33:45PM +0100, David Howells ([EMAIL PROTECTED])
wrote:
> Evgeniy Polyakov <[EMAIL PROTECTED]> wrote:
>
> > That is the same, dst is dereferenced as rtable.
> > Cloned dst is returned, so it must be put back at the ned of the usage.
>
> If that's the case, then why do you bother to clone it in route_get_raw()?
> Surely that'll give you *two* clones...
>
> BTW, it seems to work. The attached function gives me:
>
> [0mount ] <== rxrpc_assess_MTU_size() [if_mtu 1500]
>
> Thanks!
>
> David
>
> ---
> static void rxrpc_assess_MTU_size(struct rxrpc_peer *peer)
> {
> struct rtable *rt;
> struct flowi fl;
> int ret;
>
> peer->if_mtu = 1500;
>
> memset(&fl, 0, sizeof(fl));
>
> switch (peer->srx.transport.family) {
> case AF_INET:
> fl.oif = 0;
> fl.proto = IPPROTO_UDP,
> fl.nl_u.ip4_u.saddr = 0;
> fl.nl_u.ip4_u.daddr = peer->srx.transport.sin.sin_addr.s_addr;
> fl.nl_u.ip4_u.tos = 0;
> /* assume AFS.CM talking to AFS.FS */
> fl.uli_u.ports.sport = htonl(7001);
> fl.uli_u.ports.dport = htonl(7000);
> break;
> default:
> BUG();
> }
>
> ret = ip_route_output_key(&rt, &fl);
This one is quite slow compared to atomic reference increase, so yes,
there are two clones - one for main 'route', which then is being cloned
for each used in fast path. When it is not needed anymore (netchannel is
removed), the first one is dropped.
> if (ret < 0) {
> kleave(" [route err %d]", ret);
> return;
> }
>
> peer->if_mtu = dst_mtu(&rt->u.dst);
> kleave(" [if_mtu %u]", peer->if_mtu);
> }
--
Evgeniy Polyakov
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