From mboxrd@z Thu Jan  1 00:00:00 1970
From: Stephen Hemminger <shemminger@vyatta.com>
Subject: Re: IPv4/IPv6 sysctl unregistration deadlock
Date: Thu, 26 Feb 2009 17:25:07 -0800
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Cc: "Eric W. Biederman" <ebiederm@xmission.com>,
	Patrick McHardy <kaber@trash.net>,
	Linux Netdev List <netdev@vger.kernel.org>,
	"David S. Miller" <davem@davemloft.net>
To: Herbert Xu <herbert@gondor.apana.org.au>
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On Fri, 27 Feb 2009 08:59:45 +0800
Herbert Xu <herbert@gondor.apana.org.au> wrote:

> On Thu, Feb 26, 2009 at 08:49:24AM -0800, Stephen Hemminger wrote:
> >
> > -	rtnl_lock();
> > +	if (!rtnl_trylock())
> > +		return -ERESTARTSYS;
> 
> This is going to spin instead of sleep on contention, is that
> intended?
> 
> Cheers,

It walks all the way back out to VFS, which is what you have to
do since the sysctl may move.