From mboxrd@z Thu Jan  1 00:00:00 1970
From: Cong Wang <amwang@redhat.com>
Subject: Re: [PATCH 1/2] ipv6: do not hold route table lock when send ndisc
 probe
Date: Mon, 20 Aug 2012 20:15:49 +0800
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Cc: 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: Debabrata Banerjee <dbavatar@gmail.com>
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On Fri, 2012-08-17 at 14:54 -0400, Debabrata Banerjee wrote:
> Well it get rids of the deadlock for sure, but I am not sure it
> doesn't break something else, one would have to know all of this code
> much better to tell. You'll notice read_unlock_bh(&table->tb6_lock)
> for the first lock in ip6_pol_route() has more in the critical section
> after the rt6_select() call, especially that rather scary BACKTRACK()
> macro.
> 

Yeah, I noticed that, ->tb6_lock seems to protect lookup of ->tb6_root,
not sure if 'rt' may still valid after retaking this lock... Hmm,
probably calling ndisc_send_ns() inside a work is a better approach.

I will update the patch.

Thanks!