linux-kernel - Re: [PATCH 2/3] kernel,cred,kvm,security - removing superfluous rcu_read_lock

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Message-ID: <20101102072145.GA1871@jolsa.brq.redhat.com>
Date:	Tue, 2 Nov 2010 08:21:45 +0100
From:	Jiri Olsa <jolsa@...hat.com>
To:	Paolo Bonzini <pbonzini@...hat.com>
Cc:	dhowells@...hat.com, lizf@...fujitsu.com, paul.moore@...com,
	johannes@...solutions.net, dipankar@...ibm.com,
	linux-kernel@...r.kernel.org,
	containers@...ts.linux-foundation.org, kvm@...r.kernel.org
Subject: Re: [PATCH 2/3] kernel,cred,kvm,security - removing superfluous
 rcu_read_lock_held check

On Mon, Nov 01, 2010 at 11:42:23PM +0100, Paolo Bonzini wrote:
> On 11/01/2010 08:15 PM, Jiri Olsa wrote:
> >diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> >index a055742..a90a7e3 100644
> >--- a/include/linux/kvm_host.h
> >+++ b/include/linux/kvm_host.h
> >@@ -256,7 +256,6 @@ void kvm_put_kvm(struct kvm *kvm);
> >  static inline struct kvm_memslots *kvm_memslots(struct kvm *kvm)
> >  {
> >  	return rcu_dereference_check(kvm->memslots,
> >-			srcu_read_lock_held(&kvm->srcu)
> >  			|| lockdep_is_held(&kvm->slots_lock));
> >  }
> >
> 
> This is an srcu_read_lock_held, which you don't touch here:
> 
> >diff --git a/kernel/rcutorture.c b/kernel/rcutorture.c
> >index 9d8e8fb..0956a73 100644
> >--- a/kernel/rcutorture.c
> >+++ b/kernel/rcutorture.c
> >@@ -807,7 +807,6 @@ static void rcu_torture_timer(unsigned long unused)
> > 	idx = cur_ops->readlock();
> > 	completed = cur_ops->completed();
> > 	p = rcu_dereference_check(rcu_torture_current,
> >-				  rcu_read_lock_held() ||
> > 				  rcu_read_lock_bh_held() ||
> > 				  rcu_read_lock_sched_held() ||
> > 				  srcu_read_lock_held(&srcu_ctl));
> 
> I guess the kvm hunk is the incorrect one?
ops, you're right. I overlooked it, please skip the kvm hunk..

thanks,
jirka
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