Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S936006AbdLRQNH (ORCPT ); Mon, 18 Dec 2017 11:13:07 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:42964 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935990AbdLRQNB (ORCPT ); Mon, 18 Dec 2017 11:13:01 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Rajat Jain , Pavel Machek , "Rafael J. Wysocki" , Sasha Levin Subject: [PATCH 4.14 057/178] PM / s2idle: Clear the events_check_enabled flag Date: Mon, 18 Dec 2017 16:48:13 +0100 Message-Id: <20171218152922.945355136@linuxfoundation.org> X-Mailer: git-send-email 2.15.1 In-Reply-To: <20171218152920.567991776@linuxfoundation.org> References: <20171218152920.567991776@linuxfoundation.org> User-Agent: quilt/0.65 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 Content-Length: 2294 Lines: 65 4.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Rajat Jain [ Upstream commit 95b982b45122c57da2ee0b46cce70775e1d987af ] Problem: This flag does not get cleared currently in the suspend or resume path in the following cases: * In case some driver's suspend routine returns an error. * Successful s2idle case * etc? Why is this a problem: What happens is that the next suspend attempt could fail even though the user did not enable the flag by writing to /sys/power/wakeup_count. This is 1 use case how the issue can be seen (but similar use case with driver suspend failure can be thought of): 1. Read /sys/power/wakeup_count 2. echo count > /sys/power/wakeup_count 3. echo freeze > /sys/power/wakeup_count 4. Let the system suspend, and wakeup the system using some wake source that calls pm_wakeup_event() e.g. power button or something. 5. Note that the combined wakeup count would be incremented due to the pm_wakeup_event() in the resume path. 6. After resuming the events_check_enabled flag is still set. At this point if the user attempts to freeze again (without writing to /sys/power/wakeup_count), the suspend would fail even though there has been no wake event since the past resume. Address that by clearing the flag just before a resume is completed, so that it is always cleared for the corner cases mentioned above. Signed-off-by: Rajat Jain Acked-by: Pavel Machek Signed-off-by: Rafael J. Wysocki Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- kernel/power/suspend.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/kernel/power/suspend.c +++ b/kernel/power/suspend.c @@ -437,7 +437,6 @@ static int suspend_enter(suspend_state_t error = suspend_ops->enter(state); trace_suspend_resume(TPS("machine_suspend"), state, false); - events_check_enabled = false; } else if (*wakeup) { error = -EBUSY; } @@ -582,6 +581,7 @@ static int enter_state(suspend_state_t s pm_restore_gfp_mask(); Finish: + events_check_enabled = false; pm_pr_dbg("Finishing wakeup.\n"); suspend_finish(); Unlock: