From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paolo Bonzini Subject: Re: [PATCH] eventfd: Replace rcu_assign_pointer() with RCU_INIT_POINTER() Date: Mon, 18 Aug 2014 17:06:16 +0200 Message-ID: <53F21668.5090500@redhat.com> References: <20140818150129.GA14447@ada> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: paulmck@linux.vnet.ibm.com, monamagarwal123@gmail.com To: Andreea-Cristina Bernat , gleb@kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org Return-path: In-Reply-To: <20140818150129.GA14447@ada> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org Il 18/08/2014 17:01, Andreea-Cristina Bernat ha scritto: > The uses of "rcu_assign_pointer()" are NULLing out the pointers. > According to RCU_INIT_POINTER()'s block comment: > "1. This use of RCU_INIT_POINTER() is NULLing out the pointer" > it is better to use it instead of rcu_assign_pointer() because it has a > smaller overhead. > > The following Coccinelle semantic patch was used: > @@ > @@ > > - rcu_assign_pointer > + RCU_INIT_POINTER > (..., NULL) > > Signed-off-by: Andreea-Cristina Bernat > --- > virt/kvm/eventfd.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c > index 20c3af7..a49130f 100644 > --- a/virt/kvm/eventfd.c > +++ b/virt/kvm/eventfd.c > @@ -278,7 +278,7 @@ static void irqfd_update(struct kvm *kvm, struct _irqfd *irqfd, > struct kvm_kernel_irq_routing_entry *e; > > if (irqfd->gsi >= irq_rt->nr_rt_entries) { > - rcu_assign_pointer(irqfd->irq_entry, NULL); > + RCU_INIT_POINTER(irqfd->irq_entry, NULL); > return; > } > > @@ -287,7 +287,7 @@ static void irqfd_update(struct kvm *kvm, struct _irqfd *irqfd, > if (e->type == KVM_IRQ_ROUTING_MSI) > rcu_assign_pointer(irqfd->irq_entry, e); > else > - rcu_assign_pointer(irqfd->irq_entry, NULL); > + RCU_INIT_POINTER(irqfd->irq_entry, NULL); > } > } > > @@ -473,7 +473,7 @@ kvm_irqfd_deassign(struct kvm *kvm, struct kvm_irqfd *args) > * It is paired with synchronize_srcu done by caller > * of that function. > */ > - rcu_assign_pointer(irqfd->irq_entry, NULL); > + RCU_INIT_POINTER(irqfd->irq_entry, NULL); > irqfd_deactivate(irqfd); > } > } > Hi, this patch actually had been submitted already last March. It slipped through the cracks. I'm now applying both of Monam Agarwal's RCU_INIT_POINTER patches. Sorry. :) Thanks, Paolo