From patchwork Thu Jan 16 11:53:54 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jonas Meurer X-Patchwork-Id: 11336599 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 40E2F13B4 for ; Thu, 16 Jan 2020 11:54:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0009021582 for ; Thu, 16 Jan 2020 11:54:02 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=freesources.org header.i=@freesources.org header.b="R/PGHP+4" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726187AbgAPLyC (ORCPT ); Thu, 16 Jan 2020 06:54:02 -0500 Received: from mx3.freesources.org ([195.34.172.217]:51050 "EHLO mx3.freesources.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726151AbgAPLyC (ORCPT ); Thu, 16 Jan 2020 06:54:02 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=freesources.org; s=20160526; h=Content-Transfer-Encoding:Content-Type: MIME-Version:Date:Message-ID:Subject:Cc:To:From:Sender:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:In-Reply-To:References:List-Id:List-Help:List-Unsubscribe: List-Subscribe:List-Post:List-Owner:List-Archive; bh=DezD5PhW5+tytBKqleQuwyxbxvAfMTq0ZQYrNfQAdn4=; b=R/PGHP+4zZbHSNCvHLHvEGJnVX LpKGXbFN3UHBZkuvGTAYhJJsduPkZey/p7nk8Xlq5Ke4B85ZAqDWU04FyYDmHst3+BYyCVPs1kplT /J9787T+QSh/PI4HhIjGSWU32Vp6+aKnSSCFeWrdzNNAorZBzn+11OafYRvhPWL8ixDY=; Received: from anon-42-243.vpn.ipredator.se ([46.246.42.243]) by mx3.freesources.org with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.89) (envelope-from ) id 1is3in-0004eE-1l; Thu, 16 Jan 2020 11:53:57 +0000 From: Jonas Meurer To: "Rafael J. Wysocki" Cc: linux-kernel@vger.kernel.org, Linux PM , Pavel Machek , Len Brown , Tim Dittler , Yannik Sembritzki , "Rafael J. Wysocki" Autocrypt: addr=jonas@freesources.org; prefer-encrypt=mutual; keydata= mQINBEqFXAEBEAC+7gfLht8lDqGH1EPYoctDHvWQ4nk60UFDLfjqHmBGReL/9C7CyxYaqgY4 V1/DXPCmsO5PvHMSi6VPn3B81alPKMT6syQhxDN6CXETh/mrxRbTPyQVSKYdD/BvA94vgwfy iInR0N7K6J/mRxqKug14vXlABvfmyWBnW89d15OWs9qy1Ge1mHaA8UgIoUInR2mMqNHQf0nF /TtClN2uPmtv/GeGHfSSCQEjYq9Ih2Z1Re2hnwW1peEc0x7piKUXCXHGyrQdz5IE69SqV1gg vafUrWHNPWz5ZtXsihYioNi3ISuoHUjkKdn+t55en5tvWvi+2JQnMCGa/Wr7iA2EOxallR+z rQRBDe/6wp1XEz6vN1LqCeaRyVOR6q00PtN/Ot0tzPswrHKE6binqG6FBRbu+zeo87cNbMmH IAdIT3ysZCAwA2g310fBByCSiNnfhHg2GyqfC4eDtL/K7uVNqQQEon0yv8lzyUloofKER8eA W4PtahGcLLbREnekAwQMpU8y1a++QXdk1ckLoyGuBVpBX8PiRirzYVmYsGRMK2u0yIy73YYM gYpt6h+Vaoj5EyPbYuJRm3RItByzE84YBbKfA81Xn8FZWc2qTyTeKRMioTu37E/z46wSHCt9 UM89/lSz5iplUhnmdrN+u606MDbAdgxR5Lk+1UuhpPgLxIIdPwARAQABtCRKb25hcyBNZXVy ZXIgPGpvbmFzQGZyZWVzb3VyY2VzLm9yZz6JAlcEEwEKAEECGwMCHgECF4AFCwkIBwMFFQoJ CAsFFgIDAQACGQEWIQQsjNKD0+/fQziQ54NSYuf/SRBJ/gUCXP1HQwUJGBuFwgAKCRBSYuf/ 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/xNvnLsCvwVnprx9YDsQ18FaKEX+mc0yOzwKhWpT1IVShck8o1kshaaTmB1u/ZbZBgoFYcrS 30kvqVaabEbcuKmkUNTP0h4ewXdpFlx8HoUn/D+etqFR/sdZtzaSYo7F7NAf5ORb5NIyZQTf j5MR0b5PT03y/FxsG+LYDhQGxL3ZWtmPYiDT8W3BExwRg4VkRKuPVM/qDhur45CuqwNZXDQX ucOyOCxbGK0rfZasgPXkzxTWohgQwhBvw+eZ+VXzjHiRyGQ4x1Jay9eYiw7QeOiLDQxQcxLI tAzfoD+TN75zyJrLjknLC+udmMVZMcserZHCUnb9WBW4qMNyy9PI53Ha6bvfZXbZCeS3PjTo 2SCIHpzHfm/mpRL2 Subject: [PATCH v3] PM: suspend: Add sysfs attribute to control the "sync on suspend" behavior Message-ID: Date: Thu, 16 Jan 2020 12:53:54 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.3.0 MIME-Version: 1.0 Content-Language: de-DE Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org The sysfs attribute `/sys/power/sync_on_suspend` controls, whether or not filesystems are synced by the kernel before system suspend. Congruously, the behaviour of build-time switch CONFIG_SUSPEND_SKIP_SYNC is slightly changed: It now defines the run-tim default for the new sysfs attribute `/sys/power/sync_on_suspend`. The run-time attribute is added because the existing corresponding build-time Kconfig flag for (`CONFIG_SUSPEND_SKIP_SYNC`) is not flexible enough. E.g. Linux distributions that provide pre-compiled kernels usually want to stick with the default (sync filesystems before suspend) but under special conditions this needs to be changed. One example for such a special condition is user-space handling of suspending block devices (e.g. using `cryptsetup luksSuspend` or `dmsetup suspend`) before system suspend. The Kernel trying to sync filesystems after the underlying block device already got suspended obviously leads to dead-locks. Be aware that you have to take care of the filesystem sync yourself before suspending the system in those scenarios. Signed-off-by: Jonas Meurer --- Documentation/ABI/testing/sysfs-power | 13 +++++++++++ include/linux/suspend.h | 2 ++ kernel/power/Kconfig | 5 +++- kernel/power/main.c | 33 +++++++++++++++++++++++++++ kernel/power/suspend.c | 2 +- 5 files changed, 53 insertions(+), 2 deletions(-) diff --git a/Documentation/ABI/testing/sysfs-power b/Documentation/ABI/testing/sysfs-power index 6f87b9dd384b..9392a83afce8 100644 --- a/Documentation/ABI/testing/sysfs-power +++ b/Documentation/ABI/testing/sysfs-power @@ -407,3 +407,16 @@ Contact: Kalesh Singh Description: The /sys/power/suspend_stats/last_failed_step file contains the last failed step in the suspend/resume path. + +What: /sys/power/sync_on_suspend +Date: October 2019 +Contact: Jonas Meurer +Description: + This file controls whether or not the kernel will sync() + filesystems during system suspend (after freezing user space + and before suspending devices). + + Writing a "1" to this file enables the sync() and writing a + "0" disables it. Reads from the file return the current value. + The default is "1" but can be configured with the build-time + config flag "SUSPEND_SKIP_SYNC". diff --git a/include/linux/suspend.h b/include/linux/suspend.h index 6fc8843f1c9e..4a230c2f1c31 100644 --- a/include/linux/suspend.h +++ b/include/linux/suspend.h @@ -329,6 +329,7 @@ extern void arch_suspend_disable_irqs(void); extern void arch_suspend_enable_irqs(void); extern int pm_suspend(suspend_state_t state); +extern bool sync_on_suspend_enabled; #else /* !CONFIG_SUSPEND */ #define suspend_valid_only_mem NULL @@ -342,6 +343,7 @@ static inline bool pm_suspend_default_s2idle(void) { return false; } static inline void suspend_set_ops(const struct platform_suspend_ops *ops) {} static inline int pm_suspend(suspend_state_t state) { return -ENOSYS; } +static inline bool sync_on_suspend_enabled(void) { return true; } static inline bool idle_should_enter_s2idle(void) { return false; } static inline void __init pm_states_init(void) {} static inline void s2idle_set_ops(const struct platform_s2idle_ops *ops) {} diff --git a/kernel/power/Kconfig b/kernel/power/Kconfig index d3667b4075c1..7cbfbeacd68a 100644 --- a/kernel/power/Kconfig +++ b/kernel/power/Kconfig @@ -27,7 +27,10 @@ config SUSPEND_SKIP_SYNC Skip the kernel sys_sync() before freezing user processes. Some systems prefer not to pay this cost on every invocation of suspend, or they are content with invoking sync() from - user-space before invoking suspend. Say Y if that's your case. + user-space before invoking suspend. There's a run-time switch + at '/sys/power/sync_on_suspend' to configure this behaviour. + This setting changes the default for the run-tim switch. Say Y + to change the default to disable the kernel sys_sync(). config HIBERNATE_CALLBACKS bool diff --git a/kernel/power/main.c b/kernel/power/main.c index e26de7af520b..69b7a8aeca3b 100644 --- a/kernel/power/main.c +++ b/kernel/power/main.c @@ -190,6 +190,38 @@ static ssize_t mem_sleep_store(struct kobject *kobj, struct kobj_attribute *attr } power_attr(mem_sleep); + +/* + * sync_on_suspend: invoke ksys_sync_helper() before suspend. + * + * show() returns whether ksys_sync_helper() is invoked before suspend. + * store() accepts 0 or 1. 0 disables ksys_sync_helper() and 1 enables it. + */ +bool sync_on_suspend_enabled = !IS_ENABLED(CONFIG_SUSPEND_SKIP_SYNC); + +static ssize_t sync_on_suspend_show(struct kobject *kobj, + struct kobj_attribute *attr, char *buf) +{ + return sprintf(buf, "%d\n", sync_on_suspend_enabled); +} + +static ssize_t sync_on_suspend_store(struct kobject *kobj, + struct kobj_attribute *attr, + const char *buf, size_t n) +{ + unsigned long val; + + if (kstrtoul(buf, 10, &val)) + return -EINVAL; + + if (val > 1) + return -EINVAL; + + sync_on_suspend_enabled = !!val; + return n; +} + +power_attr(sync_on_suspend); #endif /* CONFIG_SUSPEND */ #ifdef CONFIG_PM_SLEEP_DEBUG @@ -855,6 +887,7 @@ static struct attribute * g[] = { &wakeup_count_attr.attr, #ifdef CONFIG_SUSPEND &mem_sleep_attr.attr, + &sync_on_suspend_attr.attr, #endif #ifdef CONFIG_PM_AUTOSLEEP &autosleep_attr.attr, diff --git a/kernel/power/suspend.c b/kernel/power/suspend.c index f3b7239f1892..2c47280fbfc7 100644 --- a/kernel/power/suspend.c +++ b/kernel/power/suspend.c @@ -564,7 +564,7 @@ static int enter_state(suspend_state_t state) if (state == PM_SUSPEND_TO_IDLE) s2idle_begin(); - if (!IS_ENABLED(CONFIG_SUSPEND_SKIP_SYNC)) { + if (sync_on_suspend_enabled) { trace_suspend_resume(TPS("sync_filesystems"), 0, true); ksys_sync_helper(); trace_suspend_resume(TPS("sync_filesystems"), 0, false);