[PATCH] teamd: use enabled option_changed to sync enabled to link_up for lb runner

[Xin Long]

LiLiang found an issue that after adding two ports into a team device with
lb mode their enabled option sometimes is false.

It was caused by the unexpected events order:

0. team_port_add() in kernel.
  1. port_change   event A1 sent to userspace.
  2. option_change event B1 sent to userspace.
  3. port_change   event A2 sent to userspace IF port is up now.
  4. process port_change event A1 and set port's enabled option 'false'.
  5. option_change event B2 sent to userspace.
  6. process option_change event B1 and sync enabled option (value = 1).
  7. process port_change event A2 and do nothing as enabled option is 1.
  8. process option_change event B2 and sync enabled option (value = 0).

In kernel, when the port is still down after dev_open(), which happens more
often since it changed to use netif_oper_up() to check the state instead of
netif_carrier_ok(), the event A2 in Step 3 can be sent at any moment. When
it's ahead of Step 4, Step 7 won't set enabled option to 1 as Step 8 comes
late.

As the port up event can be triggered by dev_watchdog at anytime in kernel,
the port_change and option_change events order can not be controlled. What
can only be done here is to correct it at Step 8, to sync enabled option to
link_up.

So this patch is to add enabled option_changed for lb mode to do this sync.

Reported-by: LiLiang 
Signed-off-by: Xin Long 
---
 teamd/teamd_runner_loadbalance.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/teamd/teamd_runner_loadbalance.c b/teamd/teamd_runner_loadbalance.c
index b9bfc13..a581472 100644
--- a/teamd/teamd_runner_loadbalance.c
+++ b/teamd/teamd_runner_loadbalance.c
@@ -109,12 +109,27 @@ static int lb_event_watch_port_hwaddr_changed(struct teamd_context *ctx,
    return err;
 }

+static int lb_event_watch_enabled_option_changed(struct teamd_context *ctx,
+						 struct team_option *option,
+						 void *priv)
+{
+	struct teamd_port *tdport;
+
+	tdport = teamd_get_port(ctx, team_get_option_port_ifindex(option));
+	if (!tdport)
+		return 0;
+
+	return lb_event_watch_port_link_changed(ctx, tdport, priv);
+}
+
 static const struct teamd_event_watch_ops lb_port_watch_ops = {
    .hwaddr_changed = lb_event_watch_hwaddr_changed,
    .port_hwaddr_changed = lb_event_watch_port_hwaddr_changed,
    .port_added = lb_event_watch_port_added,
    .port_removed = lb_event_watch_port_removed,
    .port_link_changed = lb_event_watch_port_link_changed,
+	.option_changed = lb_event_watch_enabled_option_changed,
+	.option_changed_match_name = "enabled",
 };

static int lb_init(struct teamd_context *ctx, void *priv)

[Jiri Pirko]

Mon, Apr 15, 2019 at 10:56:35AM CEST, [e-mail] wrote:
> LiLiang found an issue that after adding two ports into a team device with
> lb mode their enabled option sometimes is false.
>
> It was caused by the unexpected events order:
> team_port_add() in kernel.
> port_change   event A1 sent to userspace.
> option_change event B1 sent to userspace.
> port_change   event A2 sent to userspace IF port is up now.
> process port_change event A1 and set port's enabled option 'false'.
> option_change event B2 sent to userspace.
> process option_change event B1 and sync enabled option (value = 1).
> process port_change event A2 and do nothing as enabled option is 1.
> process option_change event B2 and sync enabled option (value = 0).
>
> In kernel, when the port is still down after dev_open(), which happens more
> often since it changed to use netif_oper_up() to check the state instead of
> netif_carrier_ok(), the event A2 in Step 3 can be sent at any moment. When
> it's ahead of Step 4, Step 7 won't set enabled option to 1 as Step 8 comes
> late.
>
> As the port up event can be triggered by dev_watchdog at anytime in kernel,
> the port_change and option_change events order can not be controlled. What
> can only be done here is to correct it at Step 8, to sync enabled option to
> link_up.
>
> So this patch is to add enabled option_changed for lb mode to do this sync.
>
> Reported-by: LiLiang 
> Signed-off-by: Xin Long

applied, thanks!