On Thu, May 14, 2009 at 10:35 AM, Stephen Hemminger <[email protected]> wrote: > On Thu, 14 May 2009 12:01:44 +0100 > Ian Campbell <[email protected]> wrote: > >> I recently noticed that my bridges were flooding traffic for a period of time >> after a topology change. These bridges are part of a Xen host and therefore >> have spanning tree disabled and forward_delay of zero. In this situation >> there >> is no reason not to begin relearning immediately after a topology change. >> >> The existing code uses hold_time == 0 to suppress learning in br_fdb_update. >> hold_time() returns forward_delay if a topology change has recently occurred >> and ageing_time if not. Setting each of those to zero has slightly different >> semantics: Setting forward_delay to zero effectively means forward >> immediately >> while setting ageing_time to zero effectively means do not learn. >> >> The solution is to not learn after a topology change only if forward_delay is >> non-zero but to retain the existing behaviour based on ageing_time if a >> topology change has not occured. > > > Unless STP is enabled, br_topology_change is bogus. It looks like, > the following would avoid the problem? > > --- a/net/bridge/br_stp.c 2009-05-14 08:33:01.795909321 -0700 > +++ b/net/bridge/br_stp.c 2009-05-14 08:34:32.839883992 -0700 > @@ -375,7 +375,8 @@ static void br_make_forwarding(struct ne > > if (br->forward_delay == 0) { > p->state = BR_STATE_FORWARDING; > - br_topology_change_detection(br); > + if (p->br->stp_enable == BR_KERNEL_STP) > + br_topology_change_detection(br); > del_timer(&p->forward_delay_timer); > } > else if (p->br->stp_enabled == BR_KERNEL_STP)
Comparing the new line to the last line of the snippet, it looks like this change is wrong. Are there really two members "stp_enable" and "stp_enabled" of the same structure? > > > _______________________________________________ > Bridge mailing list > [email protected] > https://lists.linux-foundation.org/mailman/listinfo/bridge > _______________________________________________ Bridge mailing list [email protected] https://lists.linux-foundation.org/mailman/listinfo/bridge
