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Date: Wed, 29 Aug 2007 14:52:05 +0100
From: Christoph Hellwig <hch@infradead.org>
To: Pavel Emelyanov <xemul@openvz.org>
Cc: Andrew Morton <akpm@osdl.org>,
       Trond Myklebust <trond.myklebust@fys.uio.no>,
       Oleg Nesterov <oleg@tv-sign.ru>,
       Sukadev Bhattiprolu <sukadev@us.ibm.com>,
       Linux Containers <containers@lists.osdl.org>,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] Switch nfs/callback.c to using struct pid, not pid_t
Message-ID: <20070829135205.GA13879@infradead.org>
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	Pavel Emelyanov <xemul@openvz.org>, Andrew Morton <akpm@osdl.org>,
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	Oleg Nesterov <oleg@tv-sign.ru>,
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On Wed, Aug 29, 2007 at 05:36:24PM +0400, Pavel Emelyanov wrote:
> Pid namespaces make it dangerous to use pid and tgid values
> when run in some namespace. The struct pid itself is going
> to be the only way for working with task pids, so make the
> nfs callback thread use it.
> 
> Since nfs_callback_info.pid is set to current's one and reset
> on the thread exit, it is safe not to get the struct pid. 
> 
> Since this pid is used later under lock_kernel() w/o sleeping 
> operations, checking for i to be not NULL and killing the 
> thread with kill_pid() is safe.

NACK.  This just makes the code even more obscure.  Please get rid
of the pid references entirely and convert the code to the kthread
API.