'port forced close' after failed ppp

[Aleksander Morgado]

On Fri, Mar 10, 2017 at 8:36 AM, Colin Helliwell
<colin.helliwell at ln-systems.com> wrote:
>> > > > But this brings me back (in a round-the-houses way!) to my
>> > > > original question: when the PPP fails, for example with the ports
>> > > > assigned the right way round, but on 'faulty' SIM1, why is the
>> > > > PPP port getting "forced closed" and then unable to be retried?
>> > > > My concern being if PPP fails for an external reason e.g. at the
>> > > > remote end, then it can't retry?
>> > >
>> > > Forgive my bad memory here. I think the HUP that triggers the
>> > > "forced
>> > > close" in the TTY shouldn't be received by ModemManager, it should
>> > > be
>> > > processed by pppd, which is the one that handles that
>> > > disconnection.
>> > > pppd resets all modem control lines on exit, IIRC. I recall a
>> > > similar
>> > > problem when playing with the NetworkManager integration, which is
>> > > the
>> > > one that would call pppd to establish the connection; I think I
>> > > solved
>> > > it just by making sure pppd is completely closed before
>> > > Disconnect()
>> > > is called for the modem in ModemManager (i.e. so that pppd could
>> > > recover the original state of the control lines before passing the
>> > > control of the TTY to MM through the Disconnect() call). Does that
>> > > make any sense at all?
>> >
>> > Ermmm, some...!
>> > However I've found that the same thing is happening even when the PPP
>> > is successful - MM is getting the "unexpected port hangup!" when I
>> > close PPP. I'm doing:
>> >  mmcli -m 0 --enable
>> >  mmcli -m 0 --simple-connect="apn=wap.vodafone.co.uk"
>> >  pon
>> >  ... success ...
>> >  poff
>> >  mmcli -m 0 --simple-disconnect
>> >
>> > Then trying again to connect fails with 'forced close'
>>
>> I'd consider this an MM bug then. But as a workaround, try passing the
>> "local" option to pppd, which disables its munging of modem control
>> lines and thus prevents a port hangup. Does that help?
>>
>
> No, changing 'modem' to 'local' doesn't help.
> I'm not sure where this hangup is coming from - is it being signalled from the pppd process to MM, or is it that MM is seeing a change on the port lines via the driver? (Would it help if I tried to find out?)

Just to confirm it, could you trace pppd to see if it re-sets CLOCAL
before exiting?

-- 
Aleksander
https://aleksander.es