From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paolo Bonzini Subject: Re: [PATCH v2 28/45] KVM: Use get/put_online_cpus_atomic() to prevent CPU offline Date: Wed, 26 Jun 2013 10:20:59 +0200 Message-ID: <51CAA46B.70500@redhat.com> References: <20130625202452.16593.22810.stgit@srivatsabhat.in.ibm.com> <20130625203036.16593.50377.stgit@srivatsabhat.in.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20130625203036.16593.50377.stgit@srivatsabhat.in.ibm.com> Sender: linux-arch-owner@vger.kernel.org To: "Srivatsa S. Bhat" Cc: tglx@linutronix.de, peterz@infradead.org, tj@kernel.org, oleg@redhat.com, paulmck@linux.vnet.ibm.com, rusty@rustcorp.com.au, mingo@kernel.org, akpm@linux-foundation.org, namhyung@kernel.org, walken@google.com, vincent.guittot@linaro.org, laijs@cn.fujitsu.com, rostedt@goodmis.org, wangyun@linux.vnet.ibm.com, xiaoguangrong@linux.vnet.ibm.com, sbw@mit.edu, fweisbec@gmail.com, zhong@linux.vnet.ibm.com, nikunj@linux.vnet.ibm.com, linux-pm@vger.kernel.org, linux-arch@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Gleb Natapov , kvm@vger.kernel.org List-Id: linux-pm@vger.kernel.org Il 25/06/2013 22:30, Srivatsa S. Bhat ha scritto: > Once stop_machine() is gone from the CPU offline path, we won't be able > to depend on disabling preemption to prevent CPUs from going offline > from under us. > > Use the get/put_online_cpus_atomic() APIs to prevent CPUs from going > offline, while invoking from atomic context. > > Cc: Gleb Natapov > Cc: Paolo Bonzini > Cc: kvm@vger.kernel.org > Signed-off-by: Srivatsa S. Bhat > --- > > virt/kvm/kvm_main.c | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) > > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > index 302681c..5bbfa30 100644 > --- a/virt/kvm/kvm_main.c > +++ b/virt/kvm/kvm_main.c > @@ -174,7 +174,7 @@ static bool make_all_cpus_request(struct kvm *kvm, unsigned int req) > > zalloc_cpumask_var(&cpus, GFP_ATOMIC); > > - me = get_cpu(); > + me = get_online_cpus_atomic(); > kvm_for_each_vcpu(i, vcpu, kvm) { > kvm_make_request(req, vcpu); > cpu = vcpu->cpu; > @@ -192,7 +192,7 @@ static bool make_all_cpus_request(struct kvm *kvm, unsigned int req) > smp_call_function_many(cpus, ack_flush, NULL, 1); > else > called = false; > - put_cpu(); > + put_online_cpus_atomic(); > free_cpumask_var(cpus); > return called; > } > @@ -1707,11 +1707,11 @@ void kvm_vcpu_kick(struct kvm_vcpu *vcpu) > ++vcpu->stat.halt_wakeup; > } > > - me = get_cpu(); > + me = get_online_cpus_atomic(); > if (cpu != me && (unsigned)cpu < nr_cpu_ids && cpu_online(cpu)) > if (kvm_arch_vcpu_should_kick(vcpu)) > smp_send_reschedule(cpu); > - put_cpu(); > + put_online_cpus_atomic(); > } > EXPORT_SYMBOL_GPL(kvm_vcpu_kick); > #endif /* !CONFIG_S390 */ > > -- > To unsubscribe from this list: send the line "unsubscribe linux-pm" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Acked-by: Paolo Bonzini