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Date: Mon, 20 Dec 2010 15:07:09 +0800 From: Yong Zhang <yong.zhang0@...il.com> To: Andy Walls <awalls@...metrocast.net> Cc: linux-kernel@...r.kernel.org, nicolas.mailhot@...oste.net, Tejun Heo <tj@...nel.org>, Jarod Wilson <jarod@...hat.com>, Ingo Molnar <mingo@...hat.com>, Mauro Carvalho Chehab <mchehab@...hat.com>, Hans Verkuil <hverkuil@...all.nl> Subject: Re: [PATCH] kthread_worker: Initialize dynamically allocated spinlock properly for lockdep On Sun, Dec 19, 2010 at 8:49 PM, Andy Walls <awalls@...metrocast.net> wrote: > init_kthread_worker(), via KTHREAD_WORKER_INIT(), used an > initializer for static spin_lock objects, SPIN_LOCK_UNLOCKED, on > a dynamically allocated kthread_worker object's internal spinlock_t. > This causes lockdep to gripe: > > INFO: trying to register non-static key. > the code is fine but needs lockdep annotation. > turning off the locking correctness validator. > > To keep lockdep happy, use spin_lock_init() for dynamically > allocated kthread_worker objects' internal spinlock_t. > > Reported-by: Nicolas <nicolas.mailhot@...oste.net> > Signed-off-by: Andy Walls <awalls@...metrocast.net> > > Cc: Tejun Heo <tj@...nel.org> > Cc: Jarod Wilson <jarod@...hat.com> > Cc: Ingo Molnar <mingo@...hat.com> > Cc: Mauro Carvalho Chehab <mchehab@...hat.com> > Cc: Hans Verkuil <hverkuil@...all.nl> > > diff --git a/include/linux/kthread.h b/include/linux/kthread.h > index 685ea65..e65d0b1 100644 > --- a/include/linux/kthread.h > +++ b/include/linux/kthread.h > @@ -83,7 +83,13 @@ struct kthread_work { > > static inline void init_kthread_worker(struct kthread_worker *worker) > { > - *worker = (struct kthread_worker)KTHREAD_WORKER_INIT(*worker); > + /* > + * Lockdep complains if a dynamically allocated worker's spinlock_t > + * is initialzed using SPIN_LOCK_UNLOCKED. > + */ > + spin_lock_init(&worker->lock); This will make different kthead_worker->lock initialized with one same key. You know spin_lock_init() will be like below: # define raw_spin_lock_init(lock) \ do { \ static struct lock_class_key __key; \ \ __raw_spin_lock_init((lock), #lock, &__key); \ } while (0) So we should put the real initializer to kernel/kthread.c and make init_kthread_worker() to be a MACRO. BTW, init_kthread_work() should also be changed like above because member done is a wait_queue_head. Thanks, Yong -- Only stand for myself. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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