From mboxrd@z Thu Jan  1 00:00:00 1970
From: Eric Dumazet <eric.dumazet@gmail.com>
Subject: Re: [PATCH 1/2] ipv6: do not hold route table lock when send ndisc
 probe
Date: Fri, 24 Aug 2012 11:44:44 +0200
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Cc: Debabrata Banerjee <dbavatar@gmail.com>, netdev@vger.kernel.org,
	"Banerjee, Debabrata" <dbanerje@akamai.com>,
	"David S. Miller" <davem@davemloft.net>,
	Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
	Patrick McHardy <kaber@trash.net>
To: Cong Wang <amwang@redhat.com>
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On Fri, 2012-08-24 at 17:15 +0800, Cong Wang wrote:

> 
> Right... If we call dev_hold() in the work, it is possible that the work
> is still not scheduled to running when we unregister the device. What's
> more, we can't flush work here as we are holding a read lock.

You need a global list (and a single work, not one per req), so that a
notifier can flush it at demand.