netdev - RE: [v2 Patch 1/2] s2io: add dynamic LRO disable support

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Message-ID: <FCA91A92EE52B041906A0358FC28FCC38EF13E71B8@FRE1EXCH02.hq.exar.com>
Date:	Wed, 9 Jun 2010 11:52:53 -0700
From:	Ramkrishna Vepa <Ramkrishna.Vepa@...r.com>
To:	Ben Hutchings <bhutchings@...arflare.com>,
	Amerigo Wang <amwang@...hat.com>
CC:	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"nhorman@...hat.com" <nhorman@...hat.com>,
	"sgruszka@...hat.com" <sgruszka@...hat.com>,
	"herbert.xu@...hat.com" <herbert.xu@...hat.com>,
	"davem@...emloft.net" <davem@...emloft.net>
Subject: RE: [v2 Patch 1/2] s2io: add dynamic LRO disable support

> On Wed, 2010-06-09 at 06:05 -0400, Amerigo Wang wrote:
> [...]
> > +static int s2io_ethtool_set_flags(struct net_device *dev, u32 data)
> > +{
> > +   struct s2io_nic *sp = netdev_priv(dev);
> > +   int rc = 0;
> > +   int changed = 0;
> > +
> > +   if (data & ETH_FLAG_LRO) {
> > +           if (lro_enable) {
> > +                   if (!(dev->features & NETIF_F_LRO)) {
> > +                           dev->features |= NETIF_F_LRO;
> > +                           changed = 1;
> > +                   }
> > +           } else
> > +                   rc = -EINVAL;
> > +   } else if (dev->features & NETIF_F_LRO) {
> > +           dev->features &= ~NETIF_F_LRO;
> > +           changed = 1;
> > +   }
> > +
> > +   if (changed && netif_running(dev)) {
> > +           s2io_stop_all_tx_queue(sp);
> > +           s2io_card_down(sp);
> > +           sp->lro = dev->features & NETIF_F_LRO;
> > +           rc = s2io_card_up(sp);
> > +           s2io_start_all_tx_queue(sp);
> [...]
>
> Is it safe to call s2io_start_all_tx_queue() if s2io_card_up() failed?
Ben,
Good point. If s2io_card_up() fails the chip will not be accessed, so it's safe but all transmit skbs will be freed without the user knowing the reason for failing to transmit or receive for that matter.  The other option is to return with a failure and get the watchdog timer reset the adapter.

Ram
>
> 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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