netdev - Re: [v1 PATCH] ucc_geth: fix ethtool set ring param bug

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Message-ID: <1283425907.2272.0.camel@achroite.uk.solarflarecom.com>
Date:	Thu, 02 Sep 2010 12:11:47 +0100
From:	Ben Hutchings <bhutchings@...arflare.com>
To:	Liang Li <liang.li@...driver.com>
Cc:	leoli@...escale.com, davem@...emloft.net, avorontsov@...mvista.com,
	netdev@...r.kernel.org, linuxppc-dev@...abs.org
Subject: Re: [v1 PATCH] ucc_geth: fix ethtool set ring param bug

On Thu, 2010-09-02 at 08:50 +0800, Liang Li wrote:
> On Wed, Sep 01, 2010 at 02:42:30PM +0100, Ben Hutchings wrote:
> > On Wed, 2010-09-01 at 09:43 +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:
> > [...]
> > > -	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");
> > > +		u16 rx_t;
> > > +		u16 tx_t;
> > > +		printk(KERN_INFO "Stopping interface %s.\n", netdev->name);
> > > +		ucc_geth_close(netdev);
> > > +
> > > +		rx_t = ug_info->bdRingLenRx[queue];
> > > +		tx_t = ug_info->bdRingLenTx[queue];
> > > +
> > > +		ug_info->bdRingLenRx[queue] = ring->rx_pending;
> > > +		ug_info->bdRingLenTx[queue] = ring->tx_pending;
> > > +
> > > +		printk(KERN_INFO "Reactivating interface %s.\n", netdev->name);
> > > +		ret = ucc_geth_open(netdev);
> > > +		if (ret) {
> > > +			printk(KERN_WARNING "uec_set_ringparam: set ring param for running"
> > > +					" interface %s failed. Please try to make the interface "
> > > +					" down, then try again.\n", netdev->name);
> > > +			ug_info->bdRingLenRx[queue] = rx_t;
> > > +			ug_info->bdRingLenTx[queue] = tx_t;
> > > +		}
> > [...]
> > 
> > Bringing the interface down will call ucc_geth_close(), which will try
> > to free resources that have not been allocated!
> 
> Sorry, I did not understand you on this point. There is no
> ucc_geth_close when 'open fail'. What you mean here exactly?
[...]

Read your own warning.

Ben.

-- 
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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