From: ebiederm@xmission.com (Eric W. Biederman)
To: Johannes Berg <johannes@sipsolutions.net>
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: Wed, 17 Jun 2009 17:30:40 -0700 [thread overview]
Message-ID: <m1my86qt73.fsf@fess.ebiederm.org> (raw)
In-Reply-To: <1245283327.31588.74.camel@johannes.local> (Johannes Berg's message of "Thu\, 18 Jun 2009 02\:02\:06 +0200")
Johannes Berg <johannes@sipsolutions.net> writes:
> 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 don't think we can move the barrier. But adding an extra synchronize_rcu
should be fine. We are talking about the slowest of the slow paths here.
It is so slow it even gets it's own kernel thread.
Eric
next prev parent reply other threads:[~2009-06-18 0:30 UTC|newest]
Thread overview: 15+ 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 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 22:14 ` [PATCH] wireless extensions: play with netns Johannes Berg
2009-06-17 23:24 ` Eric W. Biederman
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 0:35 ` Johannes Berg
2009-06-17 23:54 ` Eric W. Biederman
2009-06-18 0:02 ` Johannes Berg
2009-06-18 0:30 ` Eric W. Biederman [this message]
2009-06-18 0:39 ` Johannes Berg
2009-06-18 1:12 ` Eric W. Biederman
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