From patchwork Wed Sep 13 20:08:22 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Davidlohr Bueso X-Patchwork-Id: 9952015 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 1240660360 for ; Wed, 13 Sep 2017 20:09:59 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 0446128479 for ; Wed, 13 Sep 2017 20:09:59 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id EB3A628888; Wed, 13 Sep 2017 20:09:58 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id B44DD28479 for ; Wed, 13 Sep 2017 20:09:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752184AbdIMUJb (ORCPT ); Wed, 13 Sep 2017 16:09:31 -0400 Received: from smtp2.provo.novell.com ([137.65.250.81]:36202 "EHLO smtp2.provo.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752028AbdIMUIf (ORCPT ); Wed, 13 Sep 2017 16:08:35 -0400 Received: from linux-80c1.suse (prv-ext-foundry1int.gns.novell.com [137.65.251.240]) by smtp2.provo.novell.com with ESMTP (TLS encrypted); Wed, 13 Sep 2017 14:08:33 -0600 From: Davidlohr Bueso To: mingo@kernel.org, peterz@infradead.org, pbonzini@redhat.com Cc: npiggin@gmail.com, paulmck@linux.vnet.ibm.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, dave@stgolabs.net, 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> X-Mailer: git-send-email 2.12.0 In-Reply-To: <20170913200824.28067-1-dave@stgolabs.net> References: <20170913200824.28067-1-dave@stgolabs.net> Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP 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;