Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755253AbaGZTjl (ORCPT ); Sat, 26 Jul 2014 15:39:41 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:34338 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754101AbaGZTNT (ORCPT ); Sat, 26 Jul 2014 15:13:19 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, David Vrabel , Boris Ostrovsky Subject: [PATCH 3.15 020/109] xen/manage: fix potential deadlock when resuming the console Date: Sat, 26 Jul 2014 12:01:42 -0700 Message-Id: <20140726190224.447218240@linuxfoundation.org> X-Mailer: git-send-email 2.0.2 In-Reply-To: <20140726190223.834037485@linuxfoundation.org> References: <20140726190223.834037485@linuxfoundation.org> User-Agent: quilt/0.63-1 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.15-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 Signed-off-by: Greg Kroah-Hartman --- drivers/xen/manage.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) --- a/drivers/xen/manage.c +++ b/drivers/xen/manage.c @@ -109,7 +109,6 @@ static int xen_suspend(void *data) if (!si->cancelled) { xen_irq_resume(); - xen_console_resume(); xen_timer_resume(); } @@ -166,6 +165,10 @@ 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(); + raw_notifier_call_chain(&xen_resume_notifier, 0, NULL); dpm_resume_start(si.cancelled ? PMSG_THAW : PMSG_RESTORE); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/