From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752620AbdEIIa2 (ORCPT ); Tue, 9 May 2017 04:30:28 -0400 Received: from mail-pg0-f67.google.com ([74.125.83.67]:34833 "EHLO mail-pg0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752513AbdEIIaT (ORCPT ); Tue, 9 May 2017 04:30:19 -0400 From: Sergey Senozhatsky To: Petr Mladek , Steven Rostedt Cc: Jan Kara , Andrew Morton , Peter Zijlstra , "Rafael J . Wysocki" , Eric Biederman , Greg Kroah-Hartman , Jiri Slaby , Pavel Machek , Andreas Mohr , Tetsuo Handa , linux-kernel@vger.kernel.org, Sergey Senozhatsky , Sergey Senozhatsky Subject: [RFC][PATCHv3 4/5] printk: enable printk offloading Date: Tue, 9 May 2017 17:28:58 +0900 Message-Id: <20170509082859.854-5-sergey.senozhatsky@gmail.com> X-Mailer: git-send-email 2.12.2 In-Reply-To: <20170509082859.854-1-sergey.senozhatsky@gmail.com> References: <20170509082859.854-1-sergey.senozhatsky@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Initialize kernel printing thread and make printk offloading possible. By default `atomic_print_limit' is set to 0, so no offloading will take place, unless requested by user. Signed-off-by: Sergey Senozhatsky --- kernel/printk/printk.c | 38 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 38 insertions(+) diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index ba640fbcee7c..81ea575728b9 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -49,6 +49,7 @@ #include #include #include +#include #include #include @@ -2927,6 +2928,43 @@ static DEFINE_PER_CPU(struct irq_work, wake_up_klogd_work) = { .flags = IRQ_WORK_LAZY, }; +static int printk_kthread_func(void *data) +{ + while (1) { + set_current_state(TASK_INTERRUPTIBLE); + if (!test_bit(PRINTK_PENDING_OUTPUT, &printk_pending)) + schedule(); + + __set_current_state(TASK_RUNNING); + + console_lock(); + console_unlock(); + } + + return 0; +} + +/* + * Init printk kthread at late_initcall stage, after core/arch/device/etc. + * initialization. + */ +static int __init init_printk_kthread(void) +{ + struct task_struct *thread; + struct sched_param param = { .sched_priority = MAX_USER_RT_PRIO / 2 }; + + thread = kthread_run(printk_kthread_func, NULL, "printk"); + if (IS_ERR(thread)) { + pr_err("printk: unable to create printing thread\n"); + return PTR_ERR(thread); + } + + sched_setscheduler(thread, SCHED_FIFO, ¶m); + printk_kthread = thread; + return 0; +} +late_initcall(init_printk_kthread); + void wake_up_klogd(void) { preempt_disable(); -- 2.12.2