From: Cong Wang <xiyou.wangcong@gmail.com>
To: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Rolf Neugebauer <rolf.neugebauer@docker.com>,
LKML <linux-kernel@vger.kernel.org>,
Linux Kernel Network Developers <netdev@vger.kernel.org>,
Justin Cormack <justin.cormack@docker.com>,
Ian Campbell <ian.campbell@docker.com>
Subject: Re: Long delays creating a netns after deleting one (possibly RCU related)
Date: Sun, 13 Nov 2016 22:47:01 -0800 [thread overview]
Message-ID: <CAM_iQpUq14GsvGyz2xA1PkDq5YO743T68Zh2zm=NJZQ9S2Ahqg@mail.gmail.com> (raw)
In-Reply-To: <CAM_iQpUDnPfVayQv7Q+ZtC_2_ZbX9MRX=514gFpF3E6XY+GtSA@mail.gmail.com>
On Fri, Nov 11, 2016 at 4:55 PM, Cong Wang <xiyou.wangcong@gmail.com> wrote:
> On Fri, Nov 11, 2016 at 4:23 PM, Paul E. McKenney
> <paulmck@linux.vnet.ibm.com> wrote:
>>
>> Ah! This net_mutex is different than RTNL. Should synchronize_net() be
>> modified to check for net_mutex being held in addition to the current
>> checks for RTNL being held?
>>
>
> Good point!
>
> Like commit be3fc413da9eb17cce0991f214ab0, checking
> for net_mutex for this case seems to be an optimization, I assume
> synchronize_rcu_expedited() and synchronize_rcu() have the same
> behavior...
Thinking a bit more, I think commit be3fc413da9eb17cce0991f
gets wrong on rtnl_is_locked(), the lock could be locked by other
process not by the current one, therefore it should be
lockdep_rtnl_is_held() which, however, is defined only when LOCKDEP
is enabled... Sigh.
I don't see any better way than letting callers decide if they want the
expedited version or not, but this requires changes of all callers of
synchronize_net(). Hm.
next prev parent reply other threads:[~2016-11-14 6:47 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-09 15:42 Long delays creating a netns after deleting one (possibly RCU related) Rolf Neugebauer
2016-11-10 17:37 ` Cong Wang
2016-11-10 21:24 ` Paul E. McKenney
2016-11-11 13:11 ` Rolf Neugebauer
2016-11-12 0:23 ` Paul E. McKenney
2016-11-12 0:55 ` Cong Wang
2016-11-14 6:47 ` Cong Wang [this message]
2016-11-14 16:24 ` Paul E. McKenney
2016-11-14 17:44 ` Cong Wang
2016-11-14 18:14 ` Paul E. McKenney
2016-11-14 22:12 ` Eric W. Biederman
2016-11-14 22:46 ` Eric Dumazet
2016-11-14 23:09 ` Eric Dumazet
2016-11-18 0:31 ` Jarno Rajahalme
2016-11-19 0:38 ` Jarno Rajahalme
2016-11-19 0:41 ` Eric Dumazet
2016-11-14 17:29 ` Hannes Frederic Sowa
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