netdev - Re: [PATCH] wireless extensions: play with netns

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Message-ID: <m1r5xitpdh.fsf@fess.ebiederm.org>
Date:	Wed, 17 Jun 2009 16:24:58 -0700
From:	ebiederm@...ssion.com (Eric W. Biederman)
To:	Johannes Berg <johannes@...solutions.net>
Cc:	John Linville <linville@...driver.com>,
	Netdev <netdev@...r.kernel.org>,
	linux-wireless <linux-wireless@...r.kernel.org>,
	"Eric W. Biederman" <ebiederm@...stanetworks.com>,
	Alexey Dobriyan <adobriyan@...il.com>
Subject: Re: [PATCH] wireless extensions: play with netns

Johannes Berg <johannes@...solutions.net> writes:

> On Wed, 2009-06-17 at 13:46 -0700, Eric W. Biederman wrote:
>> Johannes Berg <johannes@...solutions.net> writes:
>> 
>> > This makes wireless extensions netns aware.
>> >
>> > Signed-off-by: Johannes Berg <johannes@...solutions.net>
>> > ---
>> > Is this ok, or is this racy? I guess what I'm asking is -- will
>> > for_each_net() stop iterating over a netns that is going away before the
>> > pernet exit op is called? If yes, this should be fine.
>> 
>> for_each_net requires the rtnl_lock or the net_mutex to be safe.
>> You aren't taking either so your code is racy.
>
> So it looks like I can also use rcu_read_lock(), but there's no
> for_each_net_rcu(), should there be?

I'm not using rcu safe list manipulation.  What makes it look like
rcu_read_lock() is safe?

Eric
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