Now client_obd data structure includes fields exclusively used by MGC, MDC, and OSC specifically, which makes this structure huge and hard to understand. It's reasonable to split those fields and have individual data structure for MGC, MDC, and OSC.

In order to avoid excessive code changes, it's reasonable to have the following definition:

struct client_obd_osc {
    struct client_obd osc_cli;
    /* OSC fields */
};

struct client_obd_mgc {
    struct client_obd mgc_cli;
    /* mgc fields */
};

...

This way the common code to handle client_obd connecting or disconnecting are still usable.