On Sat, May 20, 2017 at 12:25 AM, Ivan Vecera <cera@xxxxxxx> 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.
>
> 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: 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);
I'm thinking, what if the timers are running when deleting them ?
del_timer may not be going to delete it, and still have to stop itself
next time when br->stp_enabled = BR_NO_STP.
So do you think it's better to do nothing here and just leave it to be
stopped by itself when checking br->stp_enabled in
br_hello_timer_expired ?
> }
>
> br->stp_enabled = BR_NO_STP;
> --
> 2.13.0
>
