netdev - Re: [PATCH] pkt_sched: Destroy gen estimators under rtnl

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Message-ID: <20080813105052.GA6838@ff.dom.local>
Date:	Wed, 13 Aug 2008 10:50:52 +0000
From:	Jarek Poplawski <jarkao2@...il.com>
To:	Herbert Xu <herbert@...dor.apana.org.au>
Cc:	David Miller <davem@...emloft.net>, netdev@...r.kernel.org
Subject: Re: [PATCH] pkt_sched: Destroy gen estimators under rtnl_lock().

On Wed, Aug 13, 2008 at 08:42:38PM +1000, Herbert Xu wrote:
> On Wed, Aug 13, 2008 at 10:27:01AM +0000, Jarek Poplawski wrote:
> > 
> > - in net_tx_action() we can hit a place just after clear_bit() where
> > none of these bits is set. Of course, hitting this 2 times in a row
> > seems to be very unprobable, yet possible, and a lock isn't helpful
> > here, so probably some change around this would make this nicer.
> >
> > - isn't there possible some longer ping-pong between qdic_run() and
> > net_tx_action() when dev_requeue_skb() would get it back to
> > __netif_schedule() and so on (with NETDEV_TX_BUSY)?
> 
> Good point.  I think we should add an aliveness check in both
> net_tx_action and qdisc_run.  In fact the net_tx_action problem
> existed previously as well.  But it is pretty darn unlikely.

Yes, it seems qdisc_reset() doesn't have to help with this, so
probably there is needed some requeue counter or something...

Jarek P.
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