From: Tejun Heo <tj@kernel.org>
To: Cong Wang <amwang@redhat.com>
Cc: Oleg Nesterov <oleg@redhat.com>,
linux-kernel@vger.kernel.org,
Rusty Russell <rusty@rustcorp.com.au>,
akpm@linux-foundation.org, Ingo Molnar <mingo@elte.hu>
Subject: Re: [Patch] workqueue: move lockdep annotations up to destroy_workqueue()
Date: Thu, 01 Apr 2010 15:28:04 +0900 [thread overview]
Message-ID: <4BB43CF4.5020403@kernel.org> (raw)
In-Reply-To: <4BB437B8.9060802@redhat.com>
Hello,
On 04/01/2010 03:05 PM, Cong Wang wrote:
>> Hmm, it looks like I misunderstand lock_map_acquire()? From the
>> changelog, I thought it was added to complain its caller is holding
>> a lock when invoking it, thus cpu_add_remove_lock is not an
>> exception.
Oh, that just tells the code is trying to grab a pseudo lock. It's
not really a lock but to lockdep it looks like one and lockdep can use
it to compute problem cases.
> Oh, I see, wq->lockdep_map is acquired again in run_workqueue(), so
> I was wrong. :) I think you and Oleg are right, the lockdep warning
> is not irrelevant.
Yeah, I think the circular dependency you reported on wq->lockdep_map
is completed only through dependency through rtnl_mutex. If you fix
rtnl_mutex locking, it should go away too.
Thanks.
--
tejun
next prev parent reply other threads:[~2010-04-01 6:28 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-03-31 10:51 [Patch] workqueue: move lockdep annotations up to destroy_workqueue() Amerigo Wang
2010-03-31 11:25 ` Oleg Nesterov
2010-04-01 2:45 ` Cong Wang
2010-04-01 3:56 ` Tejun Heo
2010-04-01 4:09 ` Cong Wang
2010-04-01 4:14 ` Tejun Heo
2010-04-01 4:28 ` Cong Wang
2010-04-01 4:59 ` Tejun Heo
2010-04-01 5:20 ` Cong Wang
2010-04-01 6:05 ` Cong Wang
2010-04-01 6:07 ` Cong Wang
2010-04-01 6:28 ` Tejun Heo [this message]
2010-04-01 16:36 ` Oleg Nesterov
2010-04-02 5:00 ` Cong Wang
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