From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jarek Poplawski Subject: Re: [PATCH] pkt_sched: Destroy gen estimators under rtnl_lock(). Date: Thu, 21 Aug 2008 12:49:36 +0000 Message-ID: <20080821124936.GE4079@ff.dom.local> References: <20080821120112.GA7705@gondor.apana.org.au> <20080821121920.GD4079@ff.dom.local> <20080821122245.GA8533@gondor.apana.org.au> <20080821.052754.104318066.davem@davemloft.net> <20080821123538.GA8703@gondor.apana.org.au> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: David Miller , netdev@vger.kernel.org, denys@visp.net.lb To: Herbert Xu Return-path: Received: from nf-out-0910.google.com ([64.233.182.185]:57086 "EHLO nf-out-0910.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753114AbYHUMtn (ORCPT ); Thu, 21 Aug 2008 08:49:43 -0400 Received: by nf-out-0910.google.com with SMTP id d3so458788nfc.21 for ; Thu, 21 Aug 2008 05:49:41 -0700 (PDT) Content-Disposition: inline In-Reply-To: <20080821123538.GA8703@gondor.apana.org.au> Sender: netdev-owner@vger.kernel.org List-ID: On Thu, Aug 21, 2008 at 10:35:38PM +1000, Herbert Xu wrote: > On Thu, Aug 21, 2008 at 05:27:54AM -0700, David Miller wrote: > > > > This looks even worse, actually. > > > > If we just unlinked this thing, we don't want anyone finding > > it, even before we grab this lock, to adjust queue counts. > > You're right, this doesn't work at all. In fact it's been broken > even before we removed the root lock. The problem is that we used > to have one big linked list for each device. That was protected > by the device qdisc lock. Now we have one list for each txq and > qdisc_lookup walks every single txq. This means that no single > qdisc root lock can protect this anymore. > I don't think there could be such a problem, since nobody should look for such a destroyed qdisc: they look for their ancestors only. Anyway, I can't do this patch before evening, so I wait for suggestions or you could simply do it as you wish, no problem. Cheers, Jarek P.