netdev - Re: [PATCH] ucc_geth: fix ethtool set ring param bug

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Message-ID: <20100831151629.GA21442@localhost>
Date:	Tue, 31 Aug 2010 23:16:29 +0800
From:	Liang Li <liang.li@...driver.com>
To:	Ben Hutchings <bhutchings@...arflare.com>
Cc:	leoli@...escale.com, davem@...emloft.net, avorontsov@...mvista.com,
	netdev@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH] ucc_geth: fix ethtool set ring param bug

On Tue, Aug 31, 2010 at 03:41:22PM +0100, Ben Hutchings wrote:
> On Mon, 2010-08-30 at 22:47 +0800, Liang Li wrote:
> > It's common sense that when we should do change to driver ring
> > desc/buffer etc only after 'stop/shutdown' the device. When we
> > do change while devices/driver is running, kernel oops occur:
> [...]
> > diff --git a/drivers/net/ucc_geth_ethtool.c b/drivers/net/ucc_geth_ethtool.c
> > index 6f92e48..1b37aaa 100644
> > --- a/drivers/net/ucc_geth_ethtool.c
> > +++ b/drivers/net/ucc_geth_ethtool.c
> > @@ -255,13 +255,18 @@ uec_set_ringparam(struct net_device *netdev,
> >  		return -EINVAL;
> >  	}
> >  
> > -	ug_info->bdRingLenRx[queue] = ring->rx_pending;
> > -	ug_info->bdRingLenTx[queue] = ring->tx_pending;
> > -
> >  	if (netif_running(netdev)) {
> > -		/* FIXME: restart automatically */
> > -		printk(KERN_INFO
> > -			"Please re-open the interface.\n");
> > +		printk(KERN_INFO "Stopping interface %s.\n", netdev->name);
> > +		ucc_geth_close(netdev);
> > +
> > +		ug_info->bdRingLenRx[queue] = ring->rx_pending;
> > +		ug_info->bdRingLenTx[queue] = ring->tx_pending;
> > +
> > +		printk(KERN_INFO "Reactivating interface %s.\n", netdev->name);
> > +		ucc_geth_open(netdev);
> 
> What if ucc_geth_open() fails?

I did some runtime tests but did not witness the ucc_geth_open fail.
Assume it may fail for some reason, then I tend to think give out
warnings for request user to open/enable it mannually?  Or we may need
to keep the 'FIXME' line?

Thanks,
				-Liang Li

> 
> Ben.
> 
> > +	} else {
> > +		ug_info->bdRingLenRx[queue] = ring->rx_pending;
> > +		ug_info->bdRingLenTx[queue] = ring->tx_pending;
> >  	}
> >  
> >  	return ret;
> 
> -- 
> Ben Hutchings, Senior Software Engineer, Solarflare Communications
> Not speaking for my employer; that's the marketing department's job.
> They asked us to note that Solarflare product names are trademarked.
> 
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