Date: Sat, 26 Jul 2008 12:53:08 +0200
From: Jarek Poplawski <jarkao2@gmail.com>
To: David Miller <davem@davemloft.net>
Cc: johannes@sipsolutions.net, netdev@axxeo.de, peterz@infradead.org,
	Larry.Finger@lwfinger.net, kaber@trash.net,
	torvalds@linux-foundation.org, akpm@linux-foundation.org,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-wireless@vger.kernel.org, mingo@redhat.com
Subject: Re: Kernel WARNING: at net/core/dev.c:1330
	__netif_schedule+0x2c/0x98()
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On Sat, Jul 26, 2008 at 02:18:46AM -0700, David Miller wrote:
> From: Jarek Poplawski <jarkao2@gmail.com>
> Date: Fri, 25 Jul 2008 22:01:37 +0200
> 
> > On Fri, Jul 25, 2008 at 09:36:15PM +0200, Johannes Berg wrote:
> > > On Fri, 2008-07-25 at 21:34 +0200, Jarek Poplawski wrote:
> > > 
> > > No, we need to be able to lock out multiple TX paths at once.
> > 
> > IMHO, it can do the same. We could e.g. insert a locked spinlock into
> > this noop_tx_handler(), to give everyone some waiting.
> 
> I think there might be an easier way, but we may have
> to modify the state bits a little.

Yes, this looks definitely easier, but here is this one little bit
more, plus additional code to handle this in various places. Ingo's
proposal needs a (one?!) bit more thinking in one place, but it
shouldn't add even a bit to tx path (and it looks really cool!). Of
course, it could be re-considered in some other time too.

BTW, it seems with "Ingo's method" this netif_queue_stopped() check
could be removed too - the change of handlers could be done with
single qdiscs as well.

Jarek P.