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From: Johannes Berg <johannes@sipsolutions.net>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: John Linville <linville@tuxdriver.com>,
	Netdev <netdev@vger.kernel.org>,
	linux-wireless <linux-wireless@vger.kernel.org>,
	"Eric W. Biederman" <ebiederm@aristanetworks.com>,
	Alexey Dobriyan <adobriyan@gmail.com>
Subject: Re: [PATCH] wireless extensions: play with netns
Date: Thu, 18 Jun 2009 02:02:06 +0200	[thread overview]
Message-ID: <1245283327.31588.74.camel@johannes.local> (raw)
In-Reply-To: <m17hzato0r.fsf@fess.ebiederm.org>

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On Wed, 2009-06-17 at 16:54 -0700, Eric W. Biederman wrote:

> > Subject: net: make namespace iteration possible under RCU
> >
> > We already call rcu_barrier(), so all we need to take
> > care of is using proper RCU list add/del primitives.
> 
> This of course gives you a network namespace that can be found by for_each_net rcu
> while the per net exit functions are running.  I think that opens up to races
> that I don't want to think about.

Indeed. Can we move the rcu_barrier() up? Or we could insert a
synchronize_rcu() (which is sufficient for rcu_read_lock) before the
exit functions are run?

> I still haven't tracked down how I am occasionally getting time wait sockets
> with an invalid network namespace.

Ouch.

johannes

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WARNING: multiple messages have this Message-ID (diff)
From: Johannes Berg <johannes-cdvu00un1VgdHxzADdlk8Q@public.gmane.org>
To: "Eric W. Biederman" <ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>
Cc: John Linville <linville-2XuSBdqkA4R54TAoqtyWWQ@public.gmane.org>,
	Netdev <netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
	linux-wireless
	<linux-wireless-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
	"Eric W. Biederman"
	<ebiederm-BGArkANP9klv6pq1l3V1OdBPR1lH4CV8@public.gmane.org>,
	Alexey Dobriyan
	<adobriyan-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Subject: Re: [PATCH] wireless extensions: play with netns
Date: Thu, 18 Jun 2009 02:02:06 +0200	[thread overview]
Message-ID: <1245283327.31588.74.camel@johannes.local> (raw)
In-Reply-To: <m17hzato0r.fsf-+imSwln9KH6u2/kzUuoCbdi2O/JbrIOy@public.gmane.org>

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On Wed, 2009-06-17 at 16:54 -0700, Eric W. Biederman wrote:

> > Subject: net: make namespace iteration possible under RCU
> >
> > We already call rcu_barrier(), so all we need to take
> > care of is using proper RCU list add/del primitives.
> 
> This of course gives you a network namespace that can be found by for_each_net rcu
> while the per net exit functions are running.  I think that opens up to races
> that I don't want to think about.

Indeed. Can we move the rcu_barrier() up? Or we could insert a
synchronize_rcu() (which is sufficient for rcu_read_lock) before the
exit functions are run?

> I still haven't tracked down how I am occasionally getting time wait sockets
> with an invalid network namespace.

Ouch.

johannes

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  reply	other threads:[~2009-06-18  0:02 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-06-17 18:24 [PATCH] wireless extensions: play with netns Johannes Berg
2009-06-17 18:24 ` Johannes Berg
2009-06-17 20:46 ` Eric W. Biederman
2009-06-17 20:46   ` Eric W. Biederman
2009-06-17 20:50   ` Johannes Berg
2009-06-17 21:40   ` [PATCH v2] wireless extensions: make netns aware Johannes Berg
2009-06-17 21:40     ` Johannes Berg
2009-06-17 22:14   ` [PATCH] wireless extensions: play with netns Johannes Berg
2009-06-17 22:14     ` Johannes Berg
2009-06-17 23:24     ` Eric W. Biederman
2009-06-17 23:24       ` Eric W. Biederman
2009-06-17 23:41       ` Johannes Berg
2009-06-17 23:41         ` Johannes Berg
2009-06-17 23:45         ` Johannes Berg
2009-06-18  0:27           ` Eric W. Biederman
2009-06-18  0:27             ` Eric W. Biederman
2009-06-18  0:35             ` Johannes Berg
2009-06-17 23:54         ` Eric W. Biederman
2009-06-17 23:54           ` Eric W. Biederman
2009-06-18  0:02           ` Johannes Berg [this message]
2009-06-18  0:02             ` Johannes Berg
2009-06-18  0:30             ` Eric W. Biederman
2009-06-18  0:30               ` Eric W. Biederman
2009-06-18  0:39               ` Johannes Berg
2009-06-18  0:39                 ` Johannes Berg
2009-06-18  1:12                 ` Eric W. Biederman

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