On 5/19/17 7:25 PM, Ivan Vecera wrote:
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.
This really is a noop, but ok.
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.
Indeed, but the actual end result is almost as them being stopped because
in the timers there are specific checks if the STP == KERNEL_STP (see
br_transmit_config()) and the hold_timers will simply expire and not rearm
in any other mode. The only real problem is the hello_timer which continues
to rearm itself, but with Xin's earlier patch that is taken care of too.
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.
Same comment as for point 2.
The patch is a follow-up for "bridge: start hello_timer when enabling
KERNEL_STP in br_stp_start" patch from Xin Long.
I'd say this is more of a cleanup/improvement after Xin's patch and thus would
suggest targeting net-next. The only real issue is fixed by his patch.
Cc: davem@xxxxxxxxxxxxx
Cc: sashok@xxxxxxxxxxxxxxxxxxx
Cc: stephen@xxxxxxxxxxxxxxxxxx
Cc: bridge@xxxxxxxxxxxxxxxxxxxxxxxxxx
Cc: lucien.xin@xxxxxxxxx
Cc: nikolay@xxxxxxxxxxxxxxxxxxx
Signed-off-by: Ivan Vecera <cera@xxxxxxx>
---
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;
