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From: Moni Shoua <monis-hKgKHo2Ms0F+cjeuK/JdrQ@public.gmane.org>
To: Roland Dreier <rdreier-FYB4Gu1CFyUAvxtiuMwx3w@public.gmane.org>
Cc: linux-rdma <linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
	OpenFabrics General
	<general-ZwoEplunGu1OwGhvXhtEPSCwEArCW2h5@public.gmane.org>,
	Vlad <vlad-VPRAkNaXOzVS1MOuV/RT9w@public.gmane.org>
Subject: Re: [PATCH] IB/ipoib: Do not turn on carrier  to a non active port
Date: Mon, 21 Sep 2009 12:34:06 +0300	[thread overview]
Message-ID: <4AB7488E.6090700@Voltaire.COM> (raw)
In-Reply-To: <adamy4td0zp.fsf-FYB4Gu1CFyUAvxtiuMwx3w@public.gmane.org>

Roland Dreier wrote:
> And by the way, this current patch has a deadlock I think:
> 
>  > @@ -724,6 +724,8 @@ int ipoib_ib_dev_down(struct net_device *dev, int flush)
>  >  	ipoib_dbg(priv, "downing ib_dev\n");
>  >  
>  >  	clear_bit(IPOIB_FLAG_OPER_UP, &priv->flags);
>  > +	cancel_delayed_work(&priv->carrier_on_task);
> 
> ipoib_ib_dev_down() is called with rtnl held but carrier_on_task() does
> rtn_lock().  So if carrier_on_task() is running but about to take the
> rtnl when we try to do cancel_delayed_work() here, then it will wait
> forever.
> 
> I think using lockdep on a new enough kernel (2.6.30 or maybe 2.6.31)
> will report workqueue / timer vs. lock deadlocks.
> 
>  - R.
I may miss this but I don't  see how ipoib_ib_dev_down() is called with rtnl held.
Anyway, the new patch doesn't use delayed work.
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  parent reply	other threads:[~2009-09-21  9:34 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-09-17 10:16 [PATCH] IB/ipoib: Do not turn on carrier to a non active port Moni Shoua
     [not found] ` <4AB20C6C.9090005-hKgKHo2Ms0F+cjeuK/JdrQ@public.gmane.org>
2009-09-17 15:02   ` Roland Dreier
     [not found]     ` <ada4or1ehsj.fsf-FYB4Gu1CFyUAvxtiuMwx3w@public.gmane.org>
2009-09-21  9:28       ` Moni Shoua
2009-09-17 15:50 ` [ofa-general] " Roland Dreier
     [not found]   ` <adamy4td0zp.fsf-FYB4Gu1CFyUAvxtiuMwx3w@public.gmane.org>
2009-09-21  9:34     ` Moni Shoua [this message]
     [not found]       ` <4AB7488E.6090700-hKgKHo2Ms0F+cjeuK/JdrQ@public.gmane.org>
2009-09-21 15:45         ` Roland Dreier

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