From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933593AbaHHVFM (ORCPT ); Fri, 8 Aug 2014 17:05:12 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:41342 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933097AbaHHUxp (ORCPT ); Fri, 8 Aug 2014 16:53:45 -0400 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: David Vrabel , Kamal Mostafa Subject: [PATCH 3.13 113/259] xen/manage: fix potential deadlock when resuming the console Date: Fri, 8 Aug 2014 13:38:56 -0700 Message-Id: <1407530482-4483-114-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1407530482-4483-1-git-send-email-kamal@canonical.com> References: <1407530482-4483-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 3.13 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.13.11.6 -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 Signed-off-by: Kamal Mostafa --- 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 624e8dc..0bc8086 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