Current bridge code incorrectly handles starting/stopping of hello and
hold timers during STP enable/disable.

1. Timers are stopped in br_stp_start() during NO_STP->USER_STP
   transition. This is not correct as the timers are stopped in NO_STP
   case.

2. Timers are started in br_stp_stop() during USER_STP->NO_STP transition.
   This is not also correct as the timers should be stopped in NO_STP
   state.

3. Timers are NOT stopped in br_stp_stop() during KERNEL_STP->NO_STP
   transition. They should be stopped as they are running in KERNEL_STP
   state and should not run in NO_STP case.

The patch is a follow-up for "bridge: start hello_timer when enabling
KERNEL_STP in br_stp_start" patch from Xin Long.

Cc: da...@davemloft.net
Cc: sas...@cumulusnetworks.com
Cc: step...@networkplumber.org
Cc: bri...@lists.linux-foundation.org
Cc: lucien....@gmail.com
Cc: niko...@cumulusnetworks.com
Signed-off-by: Ivan Vecera <c...@cera.cz>
---
 net/bridge/br_stp_if.c | 15 +++++----------
 1 file changed, 5 insertions(+), 10 deletions(-)

diff --git a/net/bridge/br_stp_if.c b/net/bridge/br_stp_if.c
index 0db8102995a5..f137ebf27755 100644
--- a/net/bridge/br_stp_if.c
+++ b/net/bridge/br_stp_if.c
@@ -150,7 +150,6 @@ static int br_stp_call_user(struct net_bridge *br, char 
*arg)
 
 static void br_stp_start(struct net_bridge *br)
 {
-       struct net_bridge_port *p;
        int err = -ENOENT;
 
        if (net_eq(dev_net(br->dev), &init_net))
@@ -169,11 +168,6 @@ static void br_stp_start(struct net_bridge *br)
        if (!err) {
                br->stp_enabled = BR_USER_STP;
                br_debug(br, "userspace STP started\n");
-
-               /* Stop hello and hold timers */
-               del_timer(&br->hello_timer);
-               list_for_each_entry(p, &br->port_list, list)
-                       del_timer(&p->hold_timer);
        } else {
                br->stp_enabled = BR_KERNEL_STP;
                br_debug(br, "using kernel STP\n");
@@ -197,13 +191,14 @@ static void br_stp_stop(struct net_bridge *br)
                        br_err(br, "failed to stop userspace STP (%d)\n", err);
 
                /* To start timers on any ports left in blocking */
-               mod_timer(&br->hello_timer, jiffies + br->hello_time);
-               list_for_each_entry(p, &br->port_list, list)
-                       mod_timer(&p->hold_timer,
-                                 round_jiffies(jiffies + BR_HOLD_TIME));
                spin_lock_bh(&br->lock);
                br_port_state_selection(br);
                spin_unlock_bh(&br->lock);
+       } else {
+               /* BR_KERNEL_STP - stop hello and hold timers */
+               del_timer(&br->hello_timer);
+               list_for_each_entry(p, &br->port_list, list)
+                       del_timer(&p->hold_timer);
        }
 
        br->stp_enabled = BR_NO_STP;
-- 
2.13.0

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