Re: [PATCH tip/core/rcu 2/9] x86/kvm/pmu: Replace rcu_swap_protected() with rcu_replace()

From: "Paul E. McKenney" <paulmck@kernel.org>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: rcu@vger.kernel.org, linux-kernel@vger.kernel.org,
	mingo@kernel.org, jiangshanlai@gmail.com, dipankar@in.ibm.com,
	akpm@linux-foundation.org, mathieu.desnoyers@efficios.com,
	josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org,
	rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com,
	fweisbec@gmail.com, oleg@redhat.com, joel@joelfernandes.org,
	"Radim Krčmář" <rkrcmar@redhat.com>,
	"Ingo Molnar" <mingo@redhat.com>,
	"Borislav Petkov" <bp@alien8.de>,
	"H. Peter Anvin" <hpa@zytor.com>,
	x86@kernel.org, kvm@vger.kernel.org
Subject: Re: [PATCH tip/core/rcu 2/9] x86/kvm/pmu: Replace rcu_swap_protected() with rcu_replace()
Date: Sat, 5 Oct 2019 09:11:39 -0700	[thread overview]
Message-ID: <20191005161139.GF2689@paulmck-ThinkPad-P72> (raw)
In-Reply-To: <dd735e5f-c326-4b53-1126-98c5e38961d3@redhat.com>

On Thu, Oct 03, 2019 at 12:14:32PM +0200, Paolo Bonzini wrote:
> On 03/10/19 03:43, paulmck@kernel.org wrote:
> > From: "Paul E. McKenney" <paulmck@kernel.org>
> > 
> > This commit replaces the use of rcu_swap_protected() with the more
> > intuitively appealing rcu_replace() as a step towards removing
> > rcu_swap_protected().
> > 
> > Link: https://lore.kernel.org/lkml/CAHk-=wiAsJLw1egFEE=Z7-GGtM6wcvtyytXZA1+BHqta4gg6Hw@mail.gmail.com/
> > Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
> > Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
> > Cc: Paolo Bonzini <pbonzini@redhat.com>
> > Cc: "Radim Krčmář" <rkrcmar@redhat.com>
> > Cc: Thomas Gleixner <tglx@linutronix.de>
> > Cc: Ingo Molnar <mingo@redhat.com>
> > Cc: Borislav Petkov <bp@alien8.de>
> > Cc: "H. Peter Anvin" <hpa@zytor.com>
> > Cc: <x86@kernel.org>
> > Cc: <kvm@vger.kernel.org>
> > ---
> >  arch/x86/kvm/pmu.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c
> > index 46875bb..4c37266 100644
> > --- a/arch/x86/kvm/pmu.c
> > +++ b/arch/x86/kvm/pmu.c
> > @@ -416,8 +416,8 @@ int kvm_vm_ioctl_set_pmu_event_filter(struct kvm *kvm, void __user *argp)
> >  	*filter = tmp;
> >  
> >  	mutex_lock(&kvm->lock);
> > -	rcu_swap_protected(kvm->arch.pmu_event_filter, filter,
> > -			   mutex_is_locked(&kvm->lock));
> > +	filter = rcu_replace(kvm->arch.pmu_event_filter, filter,
> > +			     mutex_is_locked(&kvm->lock));
> >  	mutex_unlock(&kvm->lock);
> >  
> >  	synchronize_srcu_expedited(&kvm->srcu);
> > 
> 
> Should go without saying, but
> 
> Acked-by: Paolo Bonzini <pbonzini@redhat.com>

It never goes without saying!  ;-)

Applied, thank you!

							Thanx, Paul