[Bridge] [PATCH] net, bridge: print log message after state changed

Holger Brunck holger.brunck at keymile.com
Fri Nov 18 09:30:31 UTC 2011

On 11/17/2011 08:23 PM, David Lamparter wrote:
> On Mon, Nov 14, 2011 at 02:07:49AM -0500, David Miller wrote:
>>>> The message is therefore appropriately timed as far as I'm concerned.
>>> It's not.
>>> Please test: create a bridge with STP disabled, add an interface to the
>>> bridge and set that interface down. You get the message "... entering
>>> forwarding state". That's wrong because it's "about to enter" disabled
>>> state some lines later.
>>> All other (4) calls to br_log_state are located after the state change,
>>> see for example br_stp_enable_port() just some lines above the patch.
>> I would never expect an "entering" message to print out after the event
>> happens, and in fact I'd _always_ want to see it beforehand so that if
>> the state change caused a crash or similar it'd be that much easier
>> to pinpoint the proper location.
> There seems to be a misunderstanding here. The patch effectively does:
> -       br_log_state(p);
>         p->state = BR_STATE_DISABLED;
> +       br_log_state(p);
> and the issue it is trying to fix is not the timing but rather the code
> printing the wrong (old, now-left) state.

Yes exactly this is the problem. We got confusing state messages in the current

> I do agree that the log message should be printed before anything
> happens, so, Holger, can you brew a patch that does that?

This can't be changed easily. Because in some situations we don't know which
state we will enter at the entry point of the function.

For example  br_make_forwarding does something like
if ..
  p->state = STATE_A
else if ...
  p->state = STATE_B

So my approach would be to change the log message from "port entering state" to
"port entered state" and print it out after the state changed.


More information about the Bridge mailing list