linux-kernel - Re: [PATCH v2 1/3] Drivers: hv: vmbus: Introduce table of VMBus protocol versions

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Message-ID: <20191014095200.GA11206@andrea.guest.corp.microsoft.com>
Date:   Mon, 14 Oct 2019 11:52:00 +0200
From:   Andrea Parri <parri.andrea@...il.com>
To:     Michael Kelley <mikelley@...rosoft.com>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-hyperv@...r.kernel.org" <linux-hyperv@...r.kernel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        KY Srinivasan <kys@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        Sasha Levin <sashal@...nel.org>,
        "David S . Miller" <davem@...emloft.net>,
        vkuznets <vkuznets@...hat.com>, Dexuan Cui <decui@...rosoft.com>
Subject: Re: [PATCH v2 1/3] Drivers: hv: vmbus: Introduce table of VMBus
 protocol versions

> > @@ -244,20 +232,18 @@ int vmbus_connect(void)
> >  	 * version.
> >  	 */
> > 
> > -	version = VERSION_CURRENT;
> > +	for (i = 0; i < ARRAY_SIZE(vmbus_versions); i++) {
> > +		version = vmbus_versions[i];
> > 
> > -	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)
> > +	if (vmbus_connection.conn_state != CONNECTED)
> >  		goto cleanup;
> > 
> 
> This is a nit, but the loop exit path bugs me.  When a connection
> is established, the loop is exited by the "break", and then
> conn_state has to be tested again to decide whether the loop
> exited due to getting a connection vs. hitting the end of the list.
> Slightly cleaner in my mind would be:
> 
> 	for (i=0; ; i++) {
> 		if (i == ARRAY_SIZE(vmbus_versions))
> 			goto cleanup;
> 
> 		version  = vmbus_versions[i];
> 		ret = vmbus_negotiate_version(msginfo, version);
> 		if (ret == -ETIMEDOUT)
> 			goto cleanup;
> 
> 		if (vmbus_connection.conn_state == CONNECTED)
> 			break;
> 	}

Indeed.  I applied this locally, for the next iteration.  Thank you for
the review, Michael.

  Andrea