[BRIDGE]: fix crash in STP

Bridge would crash because of uninitailized timer if STP is used and
device was inserted into a bridge before bridge was up. This got
introduced when the delayed port checking was added.  Fix is to not
enable STP on port unless bridge is up.

Bugzilla: http://bugzilla.kernel.org/show_bug.cgi?id=6140
Dup:      http://bugzilla.kernel.org/show_bug.cgi?id=6156

Signed-off-by: Stephen Hemminger <shemminger@osdl.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 15 insertions, 14 deletions

diff --git a/net/bridge/br_if.c b/net/bridge/br_if.c
index 7fa3a5a9971f..8b38c839d539 100644
--- a/net/bridge/br_if.c
+++ b/net/bridge/br_if.c
@@ -81,26 +81,27 @@ static void port_carrier_check(void *arg)
 {
         struct net_device *dev = arg;
         struct net_bridge_port *p;
+        struct net_bridge *br;
 
         rtnl_lock();
         p = dev->br_port;
         if (!p)
                 goto done;
-
-        if (netif_carrier_ok(p->dev)) {
-                u32 cost = port_cost(p->dev);
-
-                spin_lock_bh(&p->br->lock);
-                if (p->state == BR_STATE_DISABLED) {
-                        p->path_cost = cost;
-                        br_stp_enable_port(p);
+        br = p->br;
+
+        if (netif_carrier_ok(dev))
+                p->path_cost = port_cost(dev);
+
+        if (br->dev->flags & IFF_UP) {
+                spin_lock_bh(&br->lock);
+                if (netif_carrier_ok(dev)) {
+                        if (p->state == BR_STATE_DISABLED)
+                                br_stp_enable_port(p);
+                } else {
+                        if (p->state != BR_STATE_DISABLED)
+                                br_stp_disable_port(p);
                 }
-                spin_unlock_bh(&p->br->lock);
-        } else {
-                spin_lock_bh(&p->br->lock);
-                if (p->state != BR_STATE_DISABLED)
-                        br_stp_disable_port(p);
-                spin_unlock_bh(&p->br->lock);
+                spin_unlock_bh(&br->lock);
         }
 done:
         rtnl_unlock();