From patchwork Fri Oct 7 16:57:42 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Paolo Bonzini X-Patchwork-Id: 77346 Delivered-To: patch@linaro.org Received: by 10.140.97.247 with SMTP id m110csp362196qge; Fri, 7 Oct 2016 10:13:57 -0700 (PDT) X-Received: by 10.55.191.132 with SMTP id p126mr7305801qkf.295.1475860437240; Fri, 07 Oct 2016 10:13:57 -0700 (PDT) Return-Path: Received: from lists.gnu.org (lists.gnu.org. [2001:4830:134:3::11]) by mx.google.com with ESMTPS id o128si4133700qkf.325.2016.10.07.10.13.57 for (version=TLS1 cipher=AES128-SHA bits=128/128); Fri, 07 Oct 2016 10:13:57 -0700 (PDT) Received-SPF: pass (google.com: domain of qemu-devel-bounces+patch=linaro.org@nongnu.org designates 2001:4830:134:3::11 as permitted sender) client-ip=2001:4830:134:3::11; Authentication-Results: mx.google.com; spf=pass (google.com: domain of qemu-devel-bounces+patch=linaro.org@nongnu.org designates 2001:4830:134:3::11 as permitted sender) smtp.mailfrom=qemu-devel-bounces+patch=linaro.org@nongnu.org Received: from localhost ([::1]:37411 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bsYia-0007ya-MA for patch@linaro.org; Fri, 07 Oct 2016 13:13:56 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:34387) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bsYTp-0004CP-NB for qemu-devel@nongnu.org; Fri, 07 Oct 2016 12:58:42 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bsYTl-0008EN-EX for qemu-devel@nongnu.org; Fri, 07 Oct 2016 12:58:40 -0400 Received: from mx1.redhat.com ([209.132.183.28]:34434) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bsYTl-0008Dr-84 for qemu-devel@nongnu.org; Fri, 07 Oct 2016 12:58:37 -0400 Received: from int-mx10.intmail.prod.int.phx2.redhat.com (int-mx10.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 89F1D85546; Fri, 7 Oct 2016 16:58:36 +0000 (UTC) Received: from donizetti.redhat.com (ovpn-112-69.ams2.redhat.com [10.36.112.69]) by int-mx10.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id u97Gw4tk022714; Fri, 7 Oct 2016 12:58:34 -0400 From: Paolo Bonzini To: qemu-devel@nongnu.org Date: Fri, 7 Oct 2016 18:57:42 +0200 Message-Id: <1475859483-32234-19-git-send-email-pbonzini@redhat.com> In-Reply-To: <1475859483-32234-1-git-send-email-pbonzini@redhat.com> References: <1475859483-32234-1-git-send-email-pbonzini@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.68 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.28]); Fri, 07 Oct 2016 16:58:36 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PULL 18/39] linux-user/syscall: extend lock around cpu-list X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: =?UTF-8?q?Alex=20Benn=C3=A9e?= Errors-To: qemu-devel-bounces+patch=linaro.org@nongnu.org Sender: "Qemu-devel" From: Alex Bennée There is a potential race if several threads exit at once. To serialise the exits extend the lock above the initial checking of the CPU list. Signed-off-by: Alex Bennée Message-Id: <20160930213106.20186-11-alex.bennee@linaro.org> Signed-off-by: Paolo Bonzini --- linux-user/syscall.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) -- 2.7.4 diff --git a/linux-user/syscall.c b/linux-user/syscall.c index 0815f30..fa559be 100644 --- a/linux-user/syscall.c +++ b/linux-user/syscall.c @@ -7476,13 +7476,16 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1, break; } + cpu_list_lock(); + if (CPU_NEXT(first_cpu)) { TaskState *ts; - cpu_list_lock(); /* Remove the CPU from the list. */ QTAILQ_REMOVE(&cpus, cpu, node); + cpu_list_unlock(); + ts = cpu->opaque; if (ts->child_tidptr) { put_user_u32(0, ts->child_tidptr); @@ -7495,6 +7498,8 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1, rcu_unregister_thread(); pthread_exit(NULL); } + + cpu_list_unlock(); #ifdef TARGET_GPROF _mcleanup(); #endif