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

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Message-ID: <20080813104238.GA11374@gondor.apana.org.au>
Date:	Wed, 13 Aug 2008 20:42:38 +1000
From:	Herbert Xu <herbert@...dor.apana.org.au>
To:	Jarek Poplawski <jarkao2@...il.com>
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 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.

Cheers,
-- 
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