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

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Date:	Wed, 17 Jun 2009 22:50:54 +0200
From:	Johannes Berg <johannes@...solutions.net>
To:	"Eric W. Biederman" <ebiederm@...ssion.com>
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

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.

Ah ok!

> A dying network namespace will be removed from the net_namespace_list
> (aka for_each_net) before the per net exit methods are called.
> 
> Is grabbing the rtnl_lock safe in your workqueue and is that something
> we want to do?

Ok, thanks. Well, it's a tasklet currently, but can easily be converted
to a work struct and then take the rtnl.

johannes

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