From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754828AbaHRKKt (ORCPT ); Mon, 18 Aug 2014 06:10:49 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:42401 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751512AbaHRJda (ORCPT ); Mon, 18 Aug 2014 05:33:30 -0400 From: Luis Henriques To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: David Vrabel , Luis Henriques Subject: [PATCH 3.11 004/137] xen/manage: fix potential deadlock when resuming the console Date: Mon, 18 Aug 2014 10:31:05 +0100 Message-Id: <1408354398-10226-5-git-send-email-luis.henriques@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1408354398-10226-1-git-send-email-luis.henriques@canonical.com> References: <1408354398-10226-1-git-send-email-luis.henriques@canonical.com> X-Extended-Stable: 3.11 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.11.10.15 -stable review patch. If anyone has any objections, please let me know. ------------------ From: David Vrabel commit 1b6478231c6f5f844185acb32045cf195028cfce upstream. Calling xen_console_resume() in xen_suspend() causes a warning because it locks irq_mapping_update_lock (a mutex) and this may sleep. If a userspace process is using the evtchn device then this mutex may be locked at the point of the stop_machine() call and xen_console_resume() would then deadlock. Resuming the console after stop_machine() returns avoids this deadlock. Signed-off-by: David Vrabel Reviewed-by: Boris Ostrovsky [ luis: backported to 3.11: adjusted context ] Signed-off-by: Luis Henriques --- drivers/xen/manage.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/drivers/xen/manage.c b/drivers/xen/manage.c index 624e8dc24532..0bc8086064ca 100644 --- a/drivers/xen/manage.c +++ b/drivers/xen/manage.c @@ -95,7 +95,6 @@ static int xen_suspend(void *data) if (!si->cancelled) { xen_irq_resume(); - xen_console_resume(); xen_timer_resume(); } @@ -152,6 +151,10 @@ static void do_suspend(void) err = stop_machine(xen_suspend, &si, cpumask_of(0)); + /* Resume console as early as possible. */ + if (!si.cancelled) + xen_console_resume(); + dpm_resume_start(si.cancelled ? PMSG_THAW : PMSG_RESTORE); if (err) { -- 1.9.1