From patchwork Mon Feb 10 12:45:29 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Rafael J. Wysocki" X-Patchwork-Id: 212919 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 15C2DC352A4 for ; Mon, 10 Feb 2020 12:45:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id ED42020873 for ; Mon, 10 Feb 2020 12:45:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730605AbgBJMpd (ORCPT ); Mon, 10 Feb 2020 07:45:33 -0500 Received: from cloudserver094114.home.pl ([79.96.170.134]:56364 "EHLO cloudserver094114.home.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730491AbgBJMpc (ORCPT ); Mon, 10 Feb 2020 07:45:32 -0500 Received: from 79.184.254.199.ipv4.supernova.orange.pl (79.184.254.199) (HELO kreacher.localnet) by serwer1319399.home.pl (79.96.170.134) with SMTP (IdeaSmtpServer 0.83.341) id b5b46441409b89cc; Mon, 10 Feb 2020 13:45:29 +0100 From: "Rafael J. Wysocki" To: Linux ACPI Cc: Linux PM , LKML , Zhang Rui , David Box Subject: [PATCH] ACPI: PM: s2idle: Avoid possible race related to the EC GPE Date: Mon, 10 Feb 2020 13:45:29 +0100 Message-ID: <11464642.O9o76ZdvQC@kreacher> MIME-Version: 1.0 Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org From: Rafael J. Wysocki It is theoretically possible for the ACPI EC GPE to be set after the s2idle_ops->wake() called from s2idle_loop() has returned and before the subsequent pm_wakeup_pending() check is carried out. If that happens, the resulting wakeup event will cause the system to resume even though it may be a spurious one. To avoid that race, first make the ->wake() callback in struct platform_s2idle_ops return a bool value indicating whether or not to let the system resume and rearrange s2idle_loop() to use that value instad of the direct pm_wakeup_pending() call if ->wake() is present. Next, rework acpi_s2idle_wake() to process EC events and check pm_wakeup_pending() before rearming the SCI for system wakeup to prevent it from triggering prematurely and add comments to that function to explain the rationale for the new code flow. Fixes: 56b991849009 ("PM: sleep: Simplify suspend-to-idle control flow") Cc: 5.4+ # 5.4+ Signed-off-by: Rafael J. Wysocki --- drivers/acpi/sleep.c | 46 ++++++++++++++++++++++++++++++++-------------- include/linux/suspend.h | 2 +- kernel/power/suspend.c | 9 +++++---- 3 files changed, 38 insertions(+), 19 deletions(-) Index: linux-pm/drivers/acpi/sleep.c =================================================================== --- linux-pm.orig/drivers/acpi/sleep.c +++ linux-pm/drivers/acpi/sleep.c @@ -990,21 +990,28 @@ static void acpi_s2idle_sync(void) acpi_os_wait_events_complete(); /* synchronize Notify handling */ } -static void acpi_s2idle_wake(void) +static bool acpi_s2idle_wake(void) { - /* - * If IRQD_WAKEUP_ARMED is set for the SCI at this point, the SCI has - * not triggered while suspended, so bail out. - */ - if (!acpi_sci_irq_valid() || - irqd_is_wakeup_armed(irq_get_irq_data(acpi_sci_irq))) - return; - - /* - * If there are EC events to process, the wakeup may be a spurious one - * coming from the EC. - */ - if (acpi_ec_dispatch_gpe()) { + if (!acpi_sci_irq_valid()) + return pm_wakeup_pending(); + + while (pm_wakeup_pending()) { + /* + * If IRQD_WAKEUP_ARMED is set for the SCI at this point, the + * SCI has not triggered while suspended, so bail out (the + * wakeup is pending anyway and the SCI is not the source of + * it). + */ + if (irqd_is_wakeup_armed(irq_get_irq_data(acpi_sci_irq))) + return true; + + /* + * If there are no EC events to process, the wakeup is regarded + * as a genuine one. + */ + if (!acpi_ec_dispatch_gpe()) + return true; + /* * Cancel the wakeup and process all pending events in case * there are any wakeup ones in there. @@ -1017,8 +1024,19 @@ static void acpi_s2idle_wake(void) acpi_s2idle_sync(); + /* + * The SCI is in the "suspended" state now and it cannot produce + * new wakeup events till the rearming below, so if any of them + * are pending here, they must be resulting from the processing + * of EC events above or coming from somewhere else. + */ + if (pm_wakeup_pending()) + return true; + rearm_wake_irq(acpi_sci_irq); } + + return false; } static void acpi_s2idle_restore_early(void) Index: linux-pm/include/linux/suspend.h =================================================================== --- linux-pm.orig/include/linux/suspend.h +++ linux-pm/include/linux/suspend.h @@ -191,7 +191,7 @@ struct platform_s2idle_ops { int (*begin)(void); int (*prepare)(void); int (*prepare_late)(void); - void (*wake)(void); + bool (*wake)(void); void (*restore_early)(void); void (*restore)(void); void (*end)(void); Index: linux-pm/kernel/power/suspend.c =================================================================== --- linux-pm.orig/kernel/power/suspend.c +++ linux-pm/kernel/power/suspend.c @@ -131,11 +131,12 @@ static void s2idle_loop(void) * to avoid them upfront. */ for (;;) { - if (s2idle_ops && s2idle_ops->wake) - s2idle_ops->wake(); - - if (pm_wakeup_pending()) + if (s2idle_ops && s2idle_ops->wake) { + if (s2idle_ops->wake()) + break; + } else if (pm_wakeup_pending()) { break; + } pm_wakeup_clear(false);