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[PATCH 2.6] Fix message age in bridge STP config packets

To: "Kishore A K" <kishoreak@xxxxxxxxxxxxxxx>
Subject: [PATCH 2.6] Fix message age in bridge STP config packets
From: Stephen Hemminger <shemminger@xxxxxxxx>
Date: Tue, 29 Jun 2004 15:35:03 -0700
Cc: <bridge@xxxxxxxxxxxxxx>, <davem@xxxxxxxxxx>, netdev@xxxxxxxxxxx
In-reply-to: <s0daed1b.003@EMAIL>
Organization: Open Source Development Lab
References: <s0daed1b.003@EMAIL>
Sender: netdev-bounce@xxxxxxxxxxx
This is a revised version of Kishore's patch to set message age appropriately
in STP configuration packets.

Signed-off-by: Kishore A K <KishoreAK@xxxxxxxxxxxxxxx>
Signed-off-by: Stephen Hemminger <shemminger@xxxxxxxx>

diff -Nru a/net/bridge/br_stp.c b/net/bridge/br_stp.c
--- a/net/bridge/br_stp.c       2004-06-29 14:45:50 -07:00
+++ b/net/bridge/br_stp.c       2004-06-29 14:45:50 -07:00
@@ -18,6 +18,11 @@
 #include "br_private.h"
 #include "br_private_stp.h"
 
+/* since time values in bpdu are in jiffies and then scaled (1/256)
+ * before sending, make sure that is at least one.
+ */
+#define MESSAGE_AGE_INCR       ((HZ < 256) ? 1 : (HZ/256))
+
 static const char *br_port_state_names[] = {
        [BR_STATE_DISABLED] = "disabled", 
        [BR_STATE_LISTENING] = "listening",
@@ -157,24 +162,25 @@
        bpdu.root_path_cost = br->root_path_cost;
        bpdu.bridge_id = br->bridge_id;
        bpdu.port_id = p->port_id;
-       bpdu.message_age = 0;
-       if (!br_is_root_bridge(br)) {
+       if (br_is_root_bridge(br))
+               bpdu.message_age = 0;
+       else {
                struct net_bridge_port *root
                        = br_get_port(br, br->root_port);
-               bpdu.max_age = root->message_age_timer.expires - jiffies;
-
-               if (bpdu.max_age <= 0) bpdu.max_age = 1;
+               bpdu.message_age = br->max_age
+                       - (root->message_age_timer.expires - jiffies)
+                       + MESSAGE_AGE_INCR;
        }
        bpdu.max_age = br->max_age;
        bpdu.hello_time = br->hello_time;
        bpdu.forward_delay = br->forward_delay;
 
-       br_send_config_bpdu(p, &bpdu);
-
-       p->topology_change_ack = 0;
-       p->config_pending = 0;
-       
-       mod_timer(&p->hold_timer, jiffies + BR_HOLD_TIME);
+       if (bpdu.message_age < br->max_age) {
+               br_send_config_bpdu(p, &bpdu);
+               p->topology_change_ack = 0;
+               p->config_pending = 0;
+               mod_timer(&p->hold_timer, jiffies + BR_HOLD_TIME);
+       }
 }
 
 /* called under bridge lock */

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