From: Tejun Heo <tj@kernel.org>
To: Chen Gang <gang.chen@asianux.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Oleg Nesterov <oleg@redhat.com>,
laijs@cn.fujitsu.com, Andrew Morton <akpm@linux-foundation.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] kernel/kthread.c: need spin_lock_irq() for 'worker' before main looping, since it can "WARN_ON(worker->task)".
Date: Wed, 19 Jun 2013 08:52:18 -0700 [thread overview]
Message-ID: <20130619155218.GA14881@htj.dyndns.org> (raw)
In-Reply-To: <51C18540.5060200@asianux.com>
On Wed, Jun 19, 2013 at 06:17:36PM +0800, Chen Gang wrote:
> Hmm... can 'worker->task' has chance to be not NULL before set 'current'
> to it ?
Yes, if the caller screws up and try to attach more than one workers
to the kthread_worker, which has some possibility of happening as
kthread_worker allows both attaching and detaching a worker.
> why do we use WARN_ON(worker->task) ?
To detect bugs on the caller side.
> I guess it still has chance to let "worker->task != NULL", or it should
> be BUG_ON(worker->task) instead of.
What difference does that make?
--
tejun
next prev parent reply other threads:[~2013-06-19 15:52 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-06-19 4:03 [PATCH] kernel/kthread.c: need spin_lock_irq() for 'worker' before main looping, since it can "WARN_ON(worker->task)" Chen Gang
2013-06-19 8:41 ` Tejun Heo
2013-06-19 10:17 ` Chen Gang
2013-06-19 15:52 ` Tejun Heo [this message]
2013-06-20 1:53 ` Chen Gang
2013-06-20 7:02 ` Thomas Gleixner
2013-06-20 7:37 ` Chen Gang
2013-06-20 8:28 ` Thomas Gleixner
2013-06-20 9:36 ` Chen Gang
2013-06-19 8:43 ` Thomas Gleixner
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