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Date: Thu, 14 Aug 2008 08:31:27 +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 Thu, Aug 14, 2008 at 06:16:32PM +1000, Herbert Xu wrote: > On Thu, Aug 14, 2008 at 07:59:07AM +0000, Jarek Poplawski wrote: > > > > net: Change handling of the __QDISC_STATE_SCHED flag in net_tx_action(). > > > > Change handling of the __QDISC_STATE_SCHED flag in net_tx_action() to > > enable proper control in dev_deactivate_queue(). Now, if this flag is > > seen as unset under root_lock means a qdisc can't be netif_scheduled. > > > > > > Signed-off-by: Jarek Poplawski <jarkao2@...il.com> > > Well this probably works in practice but at least on paper it > is vulnerable to live-lock if the net_tx_action side always gets > to the trylock stage and loses to the waiting side. > > An aliveness flag would be the safest. I'm not sure of your point... This patch is only to fix my yesterday's doubt #1, and it doesn't introduce, I hope, any new live-lock vulnerabity. So, if you mean doubt #2, there is needed a separate patch, but I'm not sure there is a need to add a flag. I've thougt about a counter in a Qdisc for consecutive requeues with netif_schedule, so we could break after some limit. Of course, your idea could be simpler and better, but if I could only see some code... Cheers, Jarek P. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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