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Date: Fri, 1 Aug 2008 07:41:32 +0000
From: Jarek Poplawski <jarkao2@gmail.com>
To: David Miller <davem@davemloft.net>
Cc: johannes@sipsolutions.net, netdev@axxeo.de, peterz@infradead.org,
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Subject: Re: Kernel WARNING: at net/core/dev.c:1330
	__netif_schedule+0x2c/0x98()
Message-ID: <20080801074132.GA5158@ff.dom.local> (sfid-20080801_093622_743055_C88341DB)
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On Fri, Aug 01, 2008 at 12:01:46AM -0700, David Miller wrote:
> From: Jarek Poplawski <jarkao2@gmail.com>
> Date: Fri, 1 Aug 2008 07:01:50 +0000
> 
> > On Fri, Aug 01, 2008 at 06:48:10AM +0000, Jarek Poplawski wrote:
> > > On Thu, Jul 31, 2008 at 05:29:32AM -0700, David Miller wrote:
> > ...
> > > > diff --git a/net/core/dev.c b/net/core/dev.c
> > > > index 63d6bcd..69320a5 100644
> > > > --- a/net/core/dev.c
> > > > +++ b/net/core/dev.c
> > > > @@ -4200,6 +4200,7 @@ static void netdev_init_queues(struct net_device *dev)
> > > >  {
> > > >  	netdev_init_one_queue(dev, &dev->rx_queue, NULL);
> > > >  	netdev_for_each_tx_queue(dev, netdev_init_one_queue, NULL);
> > > > +	spin_lock_init(&dev->tx_global_lock);
> > > 
> > > This will probably need some lockdep annotations similar to
> > > _xmit_lock.
> > 
> > ...BTW, we probably could also consider some optimization here: the
> > xmit_lock of the first queue could be treated as special, and only
> > the owner could do such a freezing. This would save changes of
> > functionality to non mq devices. On the other hand, it would need
> > remembering about this special treatment (so, eg. a separate lockdep
> > initialization than all the others).
> 
> I think special casing the zero's queue's lock is a bad idea.
> Having a real top-level synchronizer is a powerful tool and
> we could use it for other things.

Sure, if there is really no problem with lockdep here, there is no
need for this at all.

Thanks for the explanations,
Jarek P.