mbim-proxy vs mbimcli --no-open/--no-close

[Aleksander Morgado]

Hey Greg & others.

One thing we didn't think about is how the mbim-proxy should handle
--no-open or --no-close actions performed by the mbimcli command line
interface.

 * When the --no-close option is used by mbimcli, it won't send a last
MBIM Close request to the modem before exiting.

 * When the --no-open is used by mbimcli, it won't send an initial
MBIM Open request to the modem when starting (e.g. if --no-close was
used in the previous action).

Now, when using the proxy, it will send an explicit MBIM Close request
to the device when all clients have been disconnected from the proxy,
which prevents the usage of --no-close. How can we best handle this
situation?

One option would be to let the proxy keep an 'open count' value,
depending on the open/close requests coming from the clients, and only
if the open count drops to zero it will send the MBIM close. One
problem with this approach is that if e.g. we get ModemManager
segfault unexpectedly it won't send the MBIM close, so an
open-reference will be lost. Not sure if this is a big issue, though.

What do people think?

-- 
Aleksander
https://aleksander.es