Re: 2.6.23-rc6-mm1: IPC: sleeping function called ...

From: Paul E. McKenney
Date: Tue Sep 18 2007 - 14:29:39 EST


On Tue, Sep 18, 2007 at 09:57:15AM -0700, Andrew Morton wrote:
> On Tue, 18 Sep 2007 09:13:37 -0700 "Paul E. McKenney" <paulmck@xxxxxxxxxxxxxxxxxx> wrote:
>
> > On Tue, Sep 18, 2007 at 02:24:51PM +0200, Peter Zijlstra wrote:
> > > On Tue, 18 Sep 2007 03:34:00 -0700 Andrew Morton
> > > <akpm@xxxxxxxxxxxxxxxxxxxx> wrote:
> > >
> > > > Well, it was an optimisation. spin_lock() implies rcu_read_lock(). That's
> > > > a bit dirty and we might choose to not do that.
> > >
> > > Not true for the preemptible-rcu work. All such sites should be fixed,
> > > or at the very least heavily annotated.
> >
> > What he said!!!
> >
>
> What he said!
>
> How are you going to find all such sites?

A first step would be to look for patches in -rt that add rcu_read_lock()
or friends. A second step would be to look for rcu_dereference() without
an enclosing rcu_read_lock(), rcu_read_lock_bh(), or preempt_disable().

Beyond a certain point, this reduces to the problem of finding places
where spin_lock() was omitted, right?

Thanx, Paul
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