From 0c03150e7ea8f7fcd03cfef29385e0010b22ee92 Mon Sep 17 00:00:00 2001 From: stephen hemminger Date: Fri, 22 Jul 2011 07:47:06 +0000 Subject: [PATCH] bridge: send proper message_age in config BPDU A bridge topology with three systems: +------+ +------+ | A(2) |--| B(1) | +------+ +------+ \ / +------+ | C(3) | +------+ What is supposed to happen: * bridge with the lowest ID is elected root (for example: B) * C detects that A->C is higher cost path and puts in blocking state What happens. Bridge with lowest id (B) is elected correctly as root and things start out fine initially. But then config BPDU doesn't get transmitted from A -> C. Because of that the link from A-C is transistioned to the forwarding state. The root cause of this is that the configuration messages is generated with bogus message age, and dropped before sending. In the standardmessage_age is supposed to be: the time since the generation of the Configuration BPDU by the Root that instigated the generation of this Configuration BPDU. Reimplement this by recording the timestamp (age + jiffies) when recording config information. The old code incorrectly used the time elapsed on the ageing timer which was incorrect. See also: https://bugzilla.vyatta.com/show_bug.cgi?id=7164 Signed-off-by: Stephen Hemminger Signed-off-by: David S. Miller --- net/bridge/br_private.h | 1 + net/bridge/br_stp.c | 4 ++-- 2 files changed, 3 insertions(+), 2 deletions(-) diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h index 54578f2..78cc364 100644 --- a/net/bridge/br_private.h +++ b/net/bridge/br_private.h @@ -124,6 +124,7 @@ struct net_bridge_port bridge_id designated_bridge; u32 path_cost; u32 designated_cost; + unsigned long designated_age; struct timer_list forward_delay_timer; struct timer_list hold_timer; diff --git a/net/bridge/br_stp.c b/net/bridge/br_stp.c index bb4383e..fcff622 100644 --- a/net/bridge/br_stp.c +++ b/net/bridge/br_stp.c @@ -164,8 +164,7 @@ void br_transmit_config(struct net_bridge_port *p) else { struct net_bridge_port *root = br_get_port(br, br->root_port); - bpdu.message_age = br->max_age - - (root->message_age_timer.expires - jiffies) + bpdu.message_age = (jiffies - root->designated_age) + MESSAGE_AGE_INCR; } bpdu.max_age = br->max_age; @@ -189,6 +188,7 @@ static inline void br_record_config_information(struct net_bridge_port *p, p->designated_cost = bpdu->root_path_cost; p->designated_bridge = bpdu->bridge_id; p->designated_port = bpdu->port_id; + p->designated_age = jiffies + bpdu->message_age; mod_timer(&p->message_age_timer, jiffies + (p->br->max_age - bpdu->message_age)); -- 2.7.4