Re: [PATCH v13 17/17] net: stream: add QAPI events to report connection state

[Markus Armbruster <armbru@xxxxxxxxxx>]

Cc: Stefano Brivio

Laurent Vivier <lvivier@xxxxxxxxxx> writes:

> On 10/21/22 07:48, Markus Armbruster wrote:
>> Laurent Vivier <lvivier@xxxxxxxxxx> writes:
>> 
>>> The netdev reports NETDEV_STREAM_CONNECTED event when the backend
>>> is connected, and NETDEV_STREAM_DISCONNECTED when it is disconnected.
>>
>> Use cases?
>
> This is asked by Stefano Brivio to allow libvirt to detect if connection to 
> passt is lost and to restart passt.

Let's add something like this to the commit message:

    This lets libvirt notice when the connection is lost somehow, and
    restart the peer (such as passt).

Who's working on the libvirt part?

> I have also a patch to add a "reconnect=seconds" option, but I didn't want to 
> add it to this series.

It's okay to mention future work in commit messages, but not required.

>> Could similar event signalling be useful for other kinds of netdev
>> backends?
>
> I was wondering, but it becomes more complicated to be generic.

Making something complicated and generic where a simpler special
solution would do is the worst.

Not quite as bad (but still plenty bad) is making a few special
solutions first, then replace them all with a generic solution.

I believe we should have a good, hard think on possible applications of
a generic solution now.

There is no need to hold back this series for that.

If we conclude a generic solution is called for, we better replace this
special solution before it becomes ABI.  Either by replacing it before
we release it, or by keeping it unstable until we replace it.