From mboxrd@z Thu Jan 1 00:00:00 1970 From: Davidlohr Bueso Subject: [PATCH 5/7] kvm: Serialize wq active checks in kvm_vcpu_wake_up() Date: Wed, 13 Sep 2017 13:08:22 -0700 Message-ID: <20170913200824.28067-6-dave@stgolabs.net> References: <20170913200824.28067-1-dave@stgolabs.net> Cc: npiggin@gmail.com, paulmck@linux.vnet.ibm.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, dave@stgolabs.net, Davidlohr Bueso To: mingo@kernel.org, peterz@infradead.org, pbonzini@redhat.com Return-path: In-Reply-To: <20170913200824.28067-1-dave@stgolabs.net> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org This is a generic call and can be suceptible to races in reading the wq task_list while another task is adding itself to the list. Add a full barrier by using the swq_has_sleeper() helper. Signed-off-by: Davidlohr Bueso --- virt/kvm/kvm_main.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 6ed1c2021198..c41d903c5783 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -2186,7 +2186,7 @@ bool kvm_vcpu_wake_up(struct kvm_vcpu *vcpu) struct swait_queue_head *wqp; wqp = kvm_arch_vcpu_wq(vcpu); - if (swait_active(wqp)) { + if (swq_has_sleeper(wqp)) { swake_up(wqp); ++vcpu->stat.halt_wakeup; return true; -- 2.12.0