From mboxrd@z Thu Jan 1 00:00:00 1970 From: Fan Du Subject: Re: [RFC PATCH] sctp: Don't lookup dst if transport dst is still valid Date: Wed, 3 Jul 2013 10:39:16 +0800 Message-ID: <51D38ED4.1000000@windriver.com> References: <1372747174-23580-1-git-send-email-fan.du@windriver.com> <51D2E3C8.5050100@gmail.com> <20130702155545.GB324@hmsreliant.think-freely.org> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Vlad Yasevich , , , To: Neil Horman Return-path: Received: from mail.windriver.com ([147.11.1.11]:60883 "EHLO mail.windriver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751691Ab3GCClL (ORCPT ); Tue, 2 Jul 2013 22:41:11 -0400 In-Reply-To: <20130702155545.GB324@hmsreliant.think-freely.org> Sender: netdev-owner@vger.kernel.org List-ID: On 2013=E5=B9=B407=E6=9C=8802=E6=97=A5 23:55, Neil Horman wrote: > On Tue, Jul 02, 2013 at 10:29:28AM -0400, Vlad Yasevich wrote: >> On 07/02/2013 02:39 AM, Fan Du wrote: >>> When sctp sits on IPv6, sctp_transport_dst_check pass cookie as ZER= O, >>> as a result ip6_dst_check always fail out. This behaviour makes >>> transport->dst useless, because every sctp_packet_transmit must loo= k >>> for valid dst(Is this what supposed to be?) >>> >>> One aggressive way is to call rt_genid_bump which invalid all dst t= o >>> make new dst for transport, apparently it also hurts others. >>> I'm sure this may not be the best for all, so any commnets? >>> >>> Signed-off-by: Fan Du >>> --- >>> include/net/sctp/sctp.h | 18 ++++++++++++------ >>> net/sctp/ipv6.c | 2 ++ >>> 2 files changed, 14 insertions(+), 6 deletions(-) >>> >>> diff --git a/include/net/sctp/sctp.h b/include/net/sctp/sctp.h >>> index cd89510..f05af01 100644 >>> --- a/include/net/sctp/sctp.h >>> +++ b/include/net/sctp/sctp.h >>> @@ -719,14 +719,20 @@ static inline void sctp_v4_map_v6(union sctp_= addr *addr) >>> addr->v6.sin6_addr.s6_addr32[2] =3D htonl(0x0000ffff); >>> } >>> >>> -/* The cookie is always 0 since this is how it's used in the >>> - * pmtu code. >>> - */ >>> +/* Set cookie with the right one for IPv6 and zero for others */ >>> static inline struct dst_entry *sctp_transport_dst_check(struct s= ctp_transport *t) >>> { >>> - if (t->dst&& !dst_check(t->dst, 0)) { >>> - dst_release(t->dst); >>> - t->dst =3D NULL; >>> + >>> + if (t->dst) { >>> + struct rt6_info *rt =3D (struct rt6_info *)t->dst; >>> + u32 cookie =3D 0; >>> + >>> + if ((t->af_specific->sa_family =3D=3D AF_INET6)&& rt->rt6i_node= )=09 >>> + cookie =3D rt->rt6i_node->fn_sernum;=09 >>> + if (!dst_check(t->dst, cookie)) { >>> + dst_release(t->dst); >>> + t->dst =3D NULL; >>> + } >>> } >> >> I think it would be better if we stored the dst_cookie in the >> transport structure and initialized it at lookup time. If you do >> that, then if the route table changes, we'd correctly detect it >> without artificially bumping rt_genid (and hurting ipv4). >> > Agreed, thats how we do it for ipv4, IIRC ^^^^ Hello Neil I'm sorry I didn't find such things about IPv4. sctp_transport_dst_check -> ipv4_dst_check -> rt_is_expired ^^^^^^^^^ By "expired", currently we *do* check rt->rt_genid against net->rt_geni= d, and for IPv4, every adding/deleting an IPv4 address will bump net->rt_g= enid, (this does impact IPv6 dst checking as well) so when I delete an IPv4 a= ddress, ipv4_dst_check failed as expected to look for new dst, basically that's= what I find after checking the code for IPv4 cookie things as mentioned abov= e. Am I missing something here? > Neil > >> -vlad >> >>> >>> return t->dst; >>> diff --git a/net/sctp/ipv6.c b/net/sctp/ipv6.c >>> index 8ee553b..cfae77e 100644 >>> --- a/net/sctp/ipv6.c >>> +++ b/net/sctp/ipv6.c >>> @@ -137,6 +137,8 @@ static int sctp_inet6addr_event(struct notifier= _block *this, unsigned long ev, >>> break; >>> } >>> >>> + /* invalid all transport dst forcing to look up new dst */ >>> + rt_genid_bump(net); >>> return NOTIFY_DONE; >>> } >>> >>> >> >> > --=20 =E6=B5=AE=E6=B2=89=E9=9A=8F=E6=B5=AA=E5=8F=AA=E8=AE=B0=E4=BB=8A=E6=9C=9D= =E7=AC=91 --fan