[net-next,v2] bridge: fix hello and hold timers starting/stopping

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. The timers are already stopped in NO_STP state so
   this is confusing no-op.

2. During USER_STP->NO_STP transition the timers are started. This
   does not make sense and is confusion because the timer should not be
   active in NO_STP state.

Cc: davem@davemloft.net
Cc: sashok@cumulusnetworks.com
Cc: stephen@networkplumber.org
Cc: bridge@lists.linux-foundation.org
Cc: lucien.xin@gmail.com
Cc: nikolay@cumulusnetworks.com
Signed-off-by: Ivan Vecera <cera@cera.cz>
---
 net/bridge/br_stp_if.c | 11 -----------
 1 file changed, 11 deletions(-)

On Sat, May 20, 2017 at 1:30 AM, Ivan Vecera <cera@cera.cz> 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. The timers are already stopped in NO_STP state so
>    this is confusing no-op.
>
> 2. During USER_STP->NO_STP transition the timers are started. This
>    does not make sense and is confusion because the timer should not be
>    active in NO_STP state.
>
> Cc: davem@davemloft.net
> Cc: sashok@cumulusnetworks.com
> Cc: stephen@networkplumber.org
> Cc: bridge@lists.linux-foundation.org
> Cc: lucien.xin@gmail.com
> Cc: nikolay@cumulusnetworks.com
> Signed-off-by: Ivan Vecera <cera@cera.cz>
Reviewed-by: Xin Long <lucien.xin@gmail.com>

> ---
>  net/bridge/br_stp_if.c | 11 -----------
>  1 file changed, 11 deletions(-)
>
> diff --git a/net/bridge/br_stp_if.c b/net/bridge/br_stp_if.c
> index 08341d2aa9c9..a05027027513 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");
> @@ -187,7 +181,6 @@ static void br_stp_start(struct net_bridge *br)
>
>  static void br_stp_stop(struct net_bridge *br)
>  {
> -       struct net_bridge_port *p;
>         int err;
>
>         if (br->stp_enabled == BR_USER_STP) {
> @@ -196,10 +189,6 @@ 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);
> --
> 2.13.0
>

On 5/19/17 8:30 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. The timers are already stopped in NO_STP state so
>     this is confusing no-op.
> 
> 2. During USER_STP->NO_STP transition the timers are started. This
>     does not make sense and is confusion because the timer should not be
>     active in NO_STP state.
> 
> Cc: davem@davemloft.net
> Cc: sashok@cumulusnetworks.com
> Cc: stephen@networkplumber.org
> Cc: bridge@lists.linux-foundation.org
> Cc: lucien.xin@gmail.com
> Cc: nikolay@cumulusnetworks.com
> Signed-off-by: Ivan Vecera <cera@cera.cz>
> ---
>   net/bridge/br_stp_if.c | 11 -----------
>   1 file changed, 11 deletions(-)
> 

LGTM, thanks!

Acked-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>

From: Ivan Vecera <cera@cera.cz>
Date: Fri, 19 May 2017 19:30:43 +0200

> 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. The timers are already stopped in NO_STP state so
>    this is confusing no-op.
> 
> 2. During USER_STP->NO_STP transition the timers are started. This
>    does not make sense and is confusion because the timer should not be
>    active in NO_STP state.
> 
> Cc: davem@davemloft.net
> Cc: sashok@cumulusnetworks.com
> Cc: stephen@networkplumber.org
> Cc: bridge@lists.linux-foundation.org
> Cc: lucien.xin@gmail.com
> Cc: nikolay@cumulusnetworks.com
> Signed-off-by: Ivan Vecera <cera@cera.cz>

Applied.