linux-kernel - Re: rcu: fix hlist_bl_set_first

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Date:	Tue, 12 Mar 2013 05:46:48 -0700
From:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To:	Steven Whitehouse <swhiteho@...hat.com>
Cc:	Dipankar Sarma <dipankar@...ibm.com>, linux-kernel@...r.kernel.org,
	adas@...hat.com, hch@....de, npiggin@...il.com
Subject: Re: rcu: fix hlist_bl_set_first_rcu annotation

On Tue, Mar 12, 2013 at 09:44:29AM +0000, Steven Whitehouse wrote:
> Hi,
> 
> On Sun, 2013-02-03 at 10:39 -0800, Paul E. McKenney wrote:
> > On Wed, Jan 30, 2013 at 07:07:57PM +0000, Steven Whitehouse wrote:
> > > 
> > > Abhi noticed that we were getting a complaint from the RCU subsystem
> > > about access of an RCU protected list under the write side bit lock.
> > > This patch adds additional annotation to check both the RCU read
> > > lock and the write side bit lock before printing a message.
> > > 
> > > Signed-off-by: Steven Whitehouse <swhiteho@...hat.com>
> > > Reported-by: Abhijith Das <adas@...hat.com>
> > > Tested-by: Abhijith Das <adas@...hat.com>
> > 
> > Looks plausible to me on first glance, copying Nick Piggin and Christoph
> > Hellwig.  If they have no objections, I will queue this.
> > 
> > 							Thanx, Paul
> > 
> 
> Just a quick query to see what happened to this patch... it doesn't
> appear to have landed in Linus' tree yet, and I can't spot it in your
> git trees at korg either,

Hello, Steve,

I have queued it for 3.10, and will push it to -rcu shortly.

							Thanx, Paul

> Steve.
> 
> 
> > > diff --git a/include/linux/list_bl.h b/include/linux/list_bl.h
> > > index 31f9d75..2eb8855 100644
> > > --- a/include/linux/list_bl.h
> > > +++ b/include/linux/list_bl.h
> > > @@ -125,6 +125,11 @@ static inline void hlist_bl_unlock(struct hlist_bl_head *b)
> > >  	__bit_spin_unlock(0, (unsigned long *)b);
> > >  }
> > > 
> > > +static inline bool hlist_bl_is_locked(struct hlist_bl_head *b)
> > > +{
> > > +	return bit_spin_is_locked(0, (unsigned long *)b);
> > > +}
> > > +
> > >  /**
> > >   * hlist_bl_for_each_entry	- iterate over list of given type
> > >   * @tpos:	the type * to use as a loop cursor.
> > > diff --git a/include/linux/rculist_bl.h b/include/linux/rculist_bl.h
> > > index cf1244f..4f216c5 100644
> > > --- a/include/linux/rculist_bl.h
> > > +++ b/include/linux/rculist_bl.h
> > > @@ -20,7 +20,7 @@ static inline void hlist_bl_set_first_rcu(struct hlist_bl_head *h,
> > >  static inline struct hlist_bl_node *hlist_bl_first_rcu(struct hlist_bl_head *h)
> > >  {
> > >  	return (struct hlist_bl_node *)
> > > -		((unsigned long)rcu_dereference(h->first) & ~LIST_BL_LOCKMASK);
> > > +		((unsigned long)rcu_dereference_check(h->first, hlist_bl_is_locked(h)) & ~LIST_BL_LOCKMASK);
> > >  }
> > > 
> > >  /**
> > > 
> > > 
> > 
> 
> 

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