[PATCH] huawei: retry connect/disconnect attempt upon NDISSTATQRY failures

[Ben Chan]

>
>> BTW, should we use the "^NDISSTAT" unsolicited message to determine the
>> connection status, instead of polling via "^NDISSTATQRY?" ?
>>
>
> Definitely. If NDISSTAT unsolicited messages give us this information
> without needing to poll, and they are more reliable, then we should use
> them, as we do e.g. in the option/hso plugin.
>

I'm not sure if ^NDISSTAT unsolicited messages is always available or
reliable. Franko can probably provide more details on that.

I'm working on a patch to handle network-initiated disconnections in
the huawei plugin, which requires handling the ^NDISSTAT unsolicited
messages. As I don't know whether the ^NDISSTAT unsolicited message
can fully replace the ^NDISSTATQRY? poll, I'll probably keep both (at
least in the first patch).  That leaves a question whether it's safe
to call mm_bearer_report_disconnection() while connect_3gpp /
disconnect_3gpp is in progress. If not, I'll need to temporarily
disable the ^NDISSTAT handler while connect_3gpp / disconnect_3gpp is
polling ^NDISSTATQRY?.