Message-ID: <487F4DA6.6010009@trash.net> (sfid-20080717_154845_252147_0D419857)
Date: Thu, 17 Jul 2008 15:48:22 +0200
From: Patrick McHardy <kaber@trash.net>
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To: David Miller <davem@davemloft.net>
CC: netdev@vger.kernel.org, johannes@sipsolutions.net,
	linux-wireless@vger.kernel.org
Subject: Re: [PATCH 20/31]: pkt_sched: Perform bulk of qdisc destruction in
 RCU.
References: <20080717.051726.226040470.davem@davemloft.net>	<487F4327.1000107@trash.net> <20080717.061239.51839567.davem@davemloft.net>
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David Miller wrote:
> From: Patrick McHardy <kaber@trash.net>
> Date: Thu, 17 Jul 2008 15:03:35 +0200
> 
>> Still working my way through the patches, but this one caught my
>> eye (we had this before and it caused quite a few problems).
> 
> Indeed, it's the most delicate change.
> 
> Thanks for the info about all the tricky bits in this area.

One thought that occured to me - we could avoid all the visiblity
issues wrt. dev->qdisc_list by simply getting rid of it :)

If we move the qdisc list from the device to the root Qdisc itself,
it would become invisible automatically as soon as we assign a new
root qdisc to the netdev_queue. Iteration would become slightly
more complicated since we'd have to iterate over all netdev_queues,
but I think it should avoid most of the problems I mentioned
(besides the u32_list thing).