Re: [PATCH 1/2] Drivers: hv: vmbus: Introduce table of VMBus protocol versions

[Andrea Parri]

> > @@ -244,21 +234,18 @@ int vmbus_connect(void)
> >      * version.
> >      */
> >  
> > -   version = VERSION_CURRENT;
> > +   for (i = 0; ; i++) {
> > +           version = vmbus_versions[i];
> > +           if (version == VERSION_INVAL)
> > +                   goto cleanup;
> 
> If you use e.g. ARRAY_SIZE() you can get rid of VERSION_INVAL - and make
> this code look more natural.

Thank you for pointing this out, Vitaly.

IIUC, you're suggesting that I do:

        for (i = 0; i < ARRAY_SIZE(vmbus_versions); i++) {
                version = vmbus_versions[i];

                ret = vmbus_negotiate_version(msginfo, version);
                if (ret == -ETIMEDOUT)
                        goto cleanup;

                if (vmbus_connection.conn_state == CONNECTED)
                        break;
        }

        if (vmbus_connection.conn_state != CONNECTED)
                break;

and that I remove VERSION_INVAL from vmbus_versions, yes?

Looking at the uses of VERSION_INVAL, I find one remaining occurrence
of this macro in vmbus_bus_resume(), which does:

        if (vmbus_proto_version == VERSION_INVAL ||
            vmbus_proto_version == 0) {
                ...
        }

TBH I'm looking at vmbus_bus_resume() and vmbus_bus_suspend() for the
first time and I'm not sure about how to change such check yet... any
suggestions?

Mmh, I see that vmbus_bus_resume() and vmbus_bus_suspend() can access
vmbus_connection.conn_state: can such accesses race with a concurrent
vmbus_connect()?

Thanks,
  Andrea


> >  
> > -   do {
> >             ret = vmbus_negotiate_version(msginfo, version);
> >             if (ret == -ETIMEDOUT)
> >                     goto cleanup;
> >  
> >             if (vmbus_connection.conn_state == CONNECTED)
> >                     break;
> > -
> > -           version = vmbus_get_next_version(version);
> > -   } while (version != VERSION_INVAL);
> > -
> > -   if (version == VERSION_INVAL)
> > -           goto cleanup;
> > +   }
> >  
> >     vmbus_proto_version = version;
> >     pr_info("Vmbus version:%d.%d\n",