bridge: make user modified path cost sticky

Keep a STP port path cost value if it was set by a user.
Don't replace it with the link-speed based path cost
whenever the link goes down and comes back up.

Reported-by: Roopa Prabhu <roopa@cumulusnetworks.com>
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 4 insertions, 1 deletions

diff --git a/net/bridge/br_if.c b/net/bridge/br_if.c
index ef1b91431c6b..459dab22b3f6 100644
--- a/net/bridge/br_if.c
+++ b/net/bridge/br_if.c
@@ -67,7 +67,8 @@ void br_port_carrier_check(struct net_bridge_port *p)
         struct net_device *dev = p->dev;
         struct net_bridge *br = p->br;
 
-        if (netif_running(dev) && netif_oper_up(dev))
+        if (!(p->flags & BR_ADMIN_COST) &&
+            netif_running(dev) && netif_oper_up(dev))
                 p->path_cost = port_cost(dev);
 
         if (!netif_running(br->dev))
diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
index 3cbf5beb3d4b..d2c043a857b6 100644
--- a/net/bridge/br_private.h
+++ b/net/bridge/br_private.h
@@ -156,6 +156,7 @@ struct net_bridge_port
 #define BR_BPDU_GUARD           0x00000002
 #define BR_ROOT_BLOCK           0x00000004
 #define BR_MULTICAST_FAST_LEAVE 0x00000008
+#define BR_ADMIN_COST           0x00000010
 
 #ifdef CONFIG_BRIDGE_IGMP_SNOOPING
         u32                             multicast_startup_queries_sent;
diff --git a/net/bridge/br_stp_if.c b/net/bridge/br_stp_if.c
index 0bdb4ebd362b..d45e760141bb 100644
--- a/net/bridge/br_stp_if.c
+++ b/net/bridge/br_stp_if.c
@@ -288,6 +288,7 @@ int br_stp_set_path_cost(struct net_bridge_port *p, unsigned long path_cost)
             path_cost > BR_MAX_PATH_COST)
                 return -ERANGE;
 
+        p->flags |= BR_ADMIN_COST;
         p->path_cost = path_cost;
         br_configuration_update(p->br);
         br_port_state_selection(p->br);