netdev - RE: [EXT] Re: [PATCH net-next v2] net: mvpp2: add ethtool GOP statistics

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Date:   Tue, 7 Nov 2017 08:22:09 +0000
From:   Stefan Chulski <stefanc@...vell.com>
To:     Miquel RAYNAL <miquel.raynal@...e-electrons.com>
CC:     Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>,
        Antoine Tenart <antoine.tenart@...e-electrons.com>,
        "David S. Miller" <davem@...emloft.net>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: RE: [EXT] Re: [PATCH net-next v2] net: mvpp2: add ethtool GOP
 statistics



> -----Original Message-----
> From: Miquel RAYNAL [mailto:miquel.raynal@...e-electrons.com]
> Sent: Tuesday, November 07, 2017 12:45 AM
> To: Stefan Chulski <stefanc@...vell.com>
> Cc: Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>; Antoine Tenart
> <antoine.tenart@...e-electrons.com>; David S. Miller
> <davem@...emloft.net>; netdev@...r.kernel.org
> Subject: [EXT] Re: [PATCH net-next v2] net: mvpp2: add ethtool GOP statistics
> 
> External Email
> 
> ----------------------------------------------------------------------
> Hi Stefan,
> 
> +David Miller/Net ML
> 
> > > @@ -6844,6 +7023,10 @@ static int mvpp2_open(struct net_device
> > > *dev)
> > >
> > >  	mvpp2_start_dev(port);
> > >
> > > +	/* Start hardware statistics gathering */
> > > +	queue_delayed_work(priv->stats_queue, &priv->stats_work,
> > > +			   MVPP2_MIB_COUNTERS_STATS_DELAY);
> > > +
> > >  	return 0;
> > >
> > >  err_free_link_irq:
> > > @@ -6888,6 +7071,9 @@ static int mvpp2_stop(struct net_device *dev)
> > >  	mvpp2_cleanup_rxqs(port);
> > >  	mvpp2_cleanup_txqs(port);
> > >
> > > +	cancel_delayed_work_sync(&priv->stats_work);
> > > +	flush_workqueue(priv->stats_queue);
> > > +
> >
> > Hi Miquel,
> >
> > I think there are bug here.
> > priv is common for all ports on same CPN and they have same
> > priv->stats_work.
> >
> > For example on A7K board with 3 Ports. queue_delayed_work and
> > cancel_delayed_work_sync called for each port stop and start
> > procedure. For example:
> > If Port0 and Port1 were started, then if only Port0 stopped, delayed
> > work would be canceled for both ports.
> 
> 
> Thanks for spotting it, you are right this is a bug since I moved starting/stopping
> the queues in the opening and close procedure of the ports (to avoid using CPU
> time while no interface is actually up).
> 
> Maybe I should have a work per port, it would be easier to handle.
> 
> Thank you,
> Miquèl

I agree with you.
If delayed_work enable/disabled upon port start/stop procedure, it should be
per port and gather MIB statistics for single port.

Stefan.