Shared usage of a CID via qmi-proxy?

[James Tavares]

Hello libqmi-devel,

Back in March 2021, Aleksander Morgado wrote on a thread:

> Using the proxy or not doesn't have a direct relationship with the
> actual data connection setup. A key point to consider when setting up
> the data connection using qmicli is that you MUST make sure the WDS
> client is not released after the Start Network, i.e. you must run
> --wds-start-network always with --client-no-release-cid, and then
> reuse the WDS client cid (with --client-cid=CID) in every other qmicli
> WDS command for that connection setup, even in the --wds-stop-network.

My question is, given that a data call instance is tied to a particular WDS CID, can two clients going through the qmi-proxy share the same CID? One client would setup and tear-down the data call, as needed, as well as query data call status. This client would allocate, but never release, the CID. The second client would only query data call status, using the CID allocated by the first (the first client passes the CID to the second client via an out-of-band mechanism). Both clients would be long-lived.

Is this use case supported by the QMI protocol, generally, and the qmi-proxy, specifically? (Are there any race conditions to worry about?)  Or does each client to the proxy need to have a unique CID allocated?

(If CID cannot be shared, I don't see how two different clients could have the same "view" of the active data call status.)

Thanks in advance,
James Tavares