From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755329AbdC2J3b (ORCPT ); Wed, 29 Mar 2017 05:29:31 -0400 Received: from mail-pf0-f196.google.com ([209.85.192.196]:34881 "EHLO mail-pf0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755226AbdC2J33 (ORCPT ); Wed, 29 Mar 2017 05:29:29 -0400 From: Sergey Senozhatsky To: Steven Rostedt , Petr Mladek Cc: Jan Kara , Andrew Morton , Linus Torvalds , Peter Zijlstra , "Rafael J . Wysocki" , Eric Biederman , Greg Kroah-Hartman , Jiri Slaby , Pavel Machek , Len Brown , linux-kernel@vger.kernel.org, Sergey Senozhatsky , Sergey Senozhatsky Subject: [RFC][PATCHv2 4/8] pm: switch to printk.emergency mode in unsafe places Date: Wed, 29 Mar 2017 18:25:07 +0900 Message-Id: <20170329092511.3958-5-sergey.senozhatsky@gmail.com> X-Mailer: git-send-email 2.12.2 In-Reply-To: <20170329092511.3958-1-sergey.senozhatsky@gmail.com> References: <20170329092511.3958-1-sergey.senozhatsky@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org It's not always possible/safe to wake_up() printk kernel thread. For example, late suspend/early resume may printk() while timekeeping is not initialized yet, so calling into the scheduler may result in recursive warnings. Another thing to notice is the fact PM at some point freezes user space and kernel threads: freeze_processes() and freeze_kernel_threads(), correspondingly. Thus we need printk() to operate in old mode there and attempt to immediately flush pending kernel message to the console. This patch adds printk_emergency_begin/on sections. Signed-off-by: Sergey Senozhatsky --- kernel/power/hibernate.c | 8 ++++++++ kernel/power/suspend.c | 4 ++++ 2 files changed, 12 insertions(+) diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c index a8b978c35a6a..a8c6bb2dbcef 100644 --- a/kernel/power/hibernate.c +++ b/kernel/power/hibernate.c @@ -502,6 +502,7 @@ int hibernation_restore(int platform_mode) { int error; + printk_emergency_begin(); pm_prepare_console(); suspend_console(); pm_restrict_gfp_mask(); @@ -519,6 +520,7 @@ int hibernation_restore(int platform_mode) pm_restore_gfp_mask(); resume_console(); pm_restore_console(); + printk_emergency_end(); return error; } @@ -542,6 +544,7 @@ int hibernation_platform_enter(void) goto Close; entering_platform_hibernation = true; + printk_emergency_begin(); suspend_console(); error = dpm_suspend_start(PMSG_HIBERNATE); if (error) { @@ -589,6 +592,7 @@ int hibernation_platform_enter(void) entering_platform_hibernation = false; dpm_resume_end(PMSG_RESTORE); resume_console(); + printk_emergency_end(); Close: hibernation_ops->end(); @@ -692,6 +696,7 @@ int hibernate(void) goto Unlock; } + printk_emergency_begin(); pm_prepare_console(); error = __pm_notifier_call_chain(PM_HIBERNATION_PREPARE, -1, &nr_calls); if (error) { @@ -759,6 +764,7 @@ int hibernate(void) Exit: __pm_notifier_call_chain(PM_POST_HIBERNATION, nr_calls, NULL); pm_restore_console(); + printk_emergency_end(); atomic_inc(&snapshot_device_available); Unlock: unlock_system_sleep(); @@ -868,6 +874,7 @@ static int software_resume(void) goto Unlock; } + printk_emergency_begin(); pm_prepare_console(); error = __pm_notifier_call_chain(PM_RESTORE_PREPARE, -1, &nr_calls); if (error) { @@ -884,6 +891,7 @@ static int software_resume(void) Finish: __pm_notifier_call_chain(PM_POST_RESTORE, nr_calls, NULL); pm_restore_console(); + printk_emergency_end(); atomic_inc(&snapshot_device_available); /* For success case, the suspend path will release the lock */ Unlock: diff --git a/kernel/power/suspend.c b/kernel/power/suspend.c index 15e6baef5c73..1f897b149fc0 100644 --- a/kernel/power/suspend.c +++ b/kernel/power/suspend.c @@ -433,6 +433,7 @@ int suspend_devices_and_enter(suspend_state_t state) if (!sleep_state_supported(state)) return -ENOSYS; + printk_emergency_begin(); error = platform_suspend_begin(state); if (error) goto Close; @@ -462,6 +463,7 @@ int suspend_devices_and_enter(suspend_state_t state) Close: platform_resume_end(state); + printk_emergency_end(); return error; Recover_platform: @@ -520,6 +522,7 @@ static int enter_state(suspend_state_t state) #endif pr_debug("PM: Preparing system for sleep (%s)\n", pm_states[state]); + printk_emergency_begin(); pm_suspend_clear_flags(); error = suspend_prepare(state); if (error) @@ -537,6 +540,7 @@ static int enter_state(suspend_state_t state) Finish: pr_debug("PM: Finishing wakeup.\n"); suspend_finish(); + printk_emergency_end(); Unlock: mutex_unlock(&pm_mutex); return error; -- 2.12.2