From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754365AbdLDNt0 (ORCPT ); Mon, 4 Dec 2017 08:49:26 -0500 Received: from mail-pf0-f194.google.com ([209.85.192.194]:44599 "EHLO mail-pf0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754137AbdLDNtS (ORCPT ); Mon, 4 Dec 2017 08:49:18 -0500 X-Google-Smtp-Source: AGs4zMaA+a/xQHM4rk8/NuU/gTzX2Hz0EKuWDQnbj5XQXr8RnbuvatKoa/nwSAwIBiZ41g5cj6689Q== From: Sergey Senozhatsky To: Steven Rostedt , Petr Mladek Cc: Jan Kara , Andrew Morton , Peter Zijlstra , Rafael Wysocki , Pavel Machek , Tetsuo Handa , Tejun Heo , linux-kernel@vger.kernel.org, Sergey Senozhatsky , Sergey Senozhatsky Subject: [RFC][PATCHv6 06/12] PM: switch between printk emergency modes Date: Mon, 4 Dec 2017 22:48:19 +0900 Message-Id: <20171204134825.7822-7-sergey.senozhatsky@gmail.com> X-Mailer: git-send-email 2.15.1 In-Reply-To: <20171204134825.7822-1-sergey.senozhatsky@gmail.com> References: <20171204134825.7822-1-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 that PM at some point freezes user space and kernel threads: freeze_processes() and freeze_kernel_threads(), correspondingly. Thus we need printk() to operate in emergency mode there and attempt to immediately flush pending kernel message to the console. This patch adds printk emergency switches to dpm. Signed-off-by: Sergey Senozhatsky Suggested-by: Rafael J. Wysocki --- drivers/base/power/main.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c index c0d5f4a3611d..5bc2cf1f812c 100644 --- a/drivers/base/power/main.c +++ b/drivers/base/power/main.c @@ -34,6 +34,7 @@ #include #include #include +#include #include "../base.h" #include "power.h" @@ -1059,6 +1060,8 @@ void dpm_complete(pm_message_t state) /* Allow device probing and trigger re-probing of deferred devices */ device_unblock_probing(); trace_suspend_resume(TPS("dpm_complete"), state.event, false); + + printk_emergency_end_sync(); } /** @@ -1789,6 +1792,8 @@ int dpm_prepare(pm_message_t state) trace_suspend_resume(TPS("dpm_prepare"), state.event, true); might_sleep(); + printk_emergency_begin_sync(); + /* * Give a chance for the known devices to complete their probes, before * disable probing of devices. This sync point is important at least -- 2.15.1