From patchwork Tue Jan 26 13:47:13 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paolo Bonzini X-Patchwork-Id: 573299 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [IPv6:2001:4830:134:3::11]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id C85F21402C0 for ; Wed, 27 Jan 2016 01:10:03 +1100 (AEDT) Received: from localhost ([::1]:44143 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aO4Jl-0002OL-OY for incoming@patchwork.ozlabs.org; Tue, 26 Jan 2016 09:10:01 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:35514) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aO3yw-00016H-3H for qemu-devel@nongnu.org; Tue, 26 Jan 2016 08:48:31 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1aO3yv-0004H7-8C for qemu-devel@nongnu.org; Tue, 26 Jan 2016 08:48:30 -0500 Received: from mx1.redhat.com ([209.132.183.28]:41114) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aO3yv-0004GX-3W; Tue, 26 Jan 2016 08:48:29 -0500 Received: from int-mx10.intmail.prod.int.phx2.redhat.com (int-mx10.intmail.prod.int.phx2.redhat.com [10.5.11.23]) by mx1.redhat.com (Postfix) with ESMTPS id A740F461E2; Tue, 26 Jan 2016 13:48:28 +0000 (UTC) Received: from 640k.localdomain.com (ovpn-112-67.ams2.redhat.com [10.36.112.67]) by int-mx10.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id u0QDlNqq028272; Tue, 26 Jan 2016 08:48:27 -0500 From: Paolo Bonzini To: qemu-devel@nongnu.org Date: Tue, 26 Jan 2016 14:47:13 +0100 Message-Id: <1453816041-36362-42-git-send-email-pbonzini@redhat.com> In-Reply-To: <1453816041-36362-1-git-send-email-pbonzini@redhat.com> References: <1453816041-36362-1-git-send-email-pbonzini@redhat.com> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.23 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x X-Received-From: 209.132.183.28 Cc: "Dr. David Alan Gilbert" , qemu-stable@nongnu.org Subject: [Qemu-devel] [PULL 41/49] cpus: use broadcast on qemu_pause_cond X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org From: "Dr. David Alan Gilbert" Jiri saw a hang on pause_all_vcpus called from postcopy_start, where the cpus are all apparently stopped ('stopped' flag set) but pause_all_vcpus is still stuck on a cond_wait on qemu_paused_cond. We suspect this is happening if a qmp_stop is called at about the same time as the postcopy code calls that pause_all_vcpus; although they both should have the main lock held, Paolo spotted the cond_wait unlocks the global lock so perhaps they both could end up waiting at the same time? Signed-off-by: Dr. David Alan Gilbert Reported-by: Jiri Denemark Message-Id: <1453716498-27238-1-git-send-email-dgilbert@redhat.com> Cc: qemu-stable@nongnu.org Signed-off-by: Paolo Bonzini --- cpus.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/cpus.c b/cpus.c index ea29584..51f5ea4 100644 --- a/cpus.c +++ b/cpus.c @@ -986,7 +986,7 @@ static void qemu_wait_io_event_common(CPUState *cpu) if (cpu->stop) { cpu->stop = false; cpu->stopped = true; - qemu_cond_signal(&qemu_pause_cond); + qemu_cond_broadcast(&qemu_pause_cond); } flush_queued_work(cpu); cpu->thread_kicked = false; @@ -1387,7 +1387,7 @@ void cpu_stop_current(void) current_cpu->stop = false; current_cpu->stopped = true; cpu_exit(current_cpu); - qemu_cond_signal(&qemu_pause_cond); + qemu_cond_broadcast(&qemu_pause_cond); } }