From mboxrd@z Thu Jan  1 00:00:00 1970
From: yao zhao <dragonlinux@gmail.com>
Subject: Re: [rfc] IPVS: convert scheduler management to RCU
Date: Fri, 20 Aug 2010 13:54:11 -0400
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Cc: Changli Gao <xiaosuo@gmail.com>, Simon Horman <horms@verge.net.au>,
	lvs-devel@vger.kernel.org, netdev@vger.kernel.org,
	netfilter-devel@vger.kernel.org,
	Stephen Hemminger <shemminger@vyatta.com>,
	Wensong Zhang <wensong@linux-vs.org>,
	Julian Anastasov <ja@ssi.bg>,
	Paul E McKenney <paulmck@linux.vnet.ibm.com>
To: Eric Dumazet <eric.dumazet@gmail.com>
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On Fri, Aug 20, 2010 at 11:32 AM, Eric Dumazet <eric.dumazet@gmail.com>=
 wrote:
> Le vendredi 20 ao=FBt 2010 =E0 11:04 -0400, yao zhao a =E9crit :
>
>> The code here is deleting a global from the list, am I right? I didn=
't
>> see any called case.
>> what are you going to do more? free it? write_unlock_bh should make =
the mb.
>
>
> If you dont wait _after_ delete from list and following actions
> (kfree() without a call_rcu(), or module unload, or whatever), a read=
er
> might access your data/code and crash the box.
>
> spin_unlock_bh() wont help you at all, since only writers are freezed=
 by
> the lock (since readers only hold rcu_lock)
>
> Documentation/RCU/whatisRCU.txt line 705
>
> Documentation/RCU/checklist.txt =A015)
>
>
>
>
I read the code again and that global is in a module then you are right=
=2E
If that global is not in a module then you don't need it at all, as in
that global only functions pointer or name... which never be changed.

yao