From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754529AbeARFm7 (ORCPT ); Thu, 18 Jan 2018 00:42:59 -0500 Received: from mail-pg0-f51.google.com ([74.125.83.51]:38068 "EHLO mail-pg0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753433AbeARFm5 (ORCPT ); Thu, 18 Jan 2018 00:42:57 -0500 X-Google-Smtp-Source: ACJfBotm00ojs1lKoy+kBhBWmwsxqMB2fSK/SpacHUX+8SCv5th2CuaEH2ARddfCL2yrZ068gl811g== Date: Thu, 18 Jan 2018 14:42:51 +0900 From: Sergey Senozhatsky To: Steven Rostedt Cc: Tejun Heo , Petr Mladek , Sergey Senozhatsky , Sergey Senozhatsky , akpm@linux-foundation.org, linux-mm@kvack.org, Cong Wang , Dave Hansen , Johannes Weiner , Mel Gorman , Michal Hocko , Vlastimil Babka , Peter Zijlstra , Linus Torvalds , Jan Kara , Mathieu Desnoyers , Tetsuo Handa , rostedt@rostedt.homelinux.com, Byungchul Park , Pavel Machek , linux-kernel@vger.kernel.org Subject: Re: [PATCH v5 0/2] printk: Console owner and waiter logic cleanup Message-ID: <20180118054251.GB6529@jagdpanzerIV> References: <20180111045817.GA494@jagdpanzerIV> <20180111093435.GA24497@linux.suse> <20180111103845.GB477@jagdpanzerIV> <20180111112908.50de440a@vmware.local.home> <20180111203057.5b1a8f8f@gandalf.local.home> <20180111215547.2f66a23a@gandalf.local.home> <20180116194456.GS3460072@devbig577.frc2.facebook.com> <20180117091208.ezvuhumnsarz5thh@pathway.suse.cz> <20180117151509.GT3460072@devbig577.frc2.facebook.com> <20180117121251.7283a56e@gandalf.local.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180117121251.7283a56e@gandalf.local.home> User-Agent: Mutt/1.9.2 (2017-12-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On (01/17/18 12:12), Steven Rostedt wrote: [..] > /* > * Can we actually use the console at this time on this cpu? > @@ -2333,6 +2390,7 @@ void console_unlock(void) > > for (;;) { > struct printk_log *msg; > + bool offload; > size_t ext_len = 0; > size_t len; > > @@ -2393,15 +2451,20 @@ void console_unlock(void) > * waiter waiting to take over. > */ > console_lock_spinning_enable(); > + offload = recursion_check_start(); > > stop_critical_timings(); /* don't trace print latency */ > call_console_drivers(ext_text, ext_len, text, len); > start_critical_timings(); > > + recursion_check_finish(offload); > + > if (console_lock_spinning_disable_and_check()) { > printk_safe_exit_irqrestore(flags); > return; > } > + if (offload) > + kick_offload_thread(); > > printk_safe_exit_irqrestore(flags); ^^^^^^^^^^^^^^^^ but we call console drivers in printk_safe. printk -> console_drivers -> printk will be redirected to this-CPU printk_safe buffer. -ss From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-f72.google.com (mail-pg0-f72.google.com [74.125.83.72]) by kanga.kvack.org (Postfix) with ESMTP id 116B66B0069 for ; Thu, 18 Jan 2018 00:42:58 -0500 (EST) Received: by mail-pg0-f72.google.com with SMTP id m3so1862716pgd.20 for ; Wed, 17 Jan 2018 21:42:58 -0800 (PST) Received: from mail-sor-f41.google.com (mail-sor-f41.google.com. [209.85.220.41]) by mx.google.com with SMTPS id p13sor2053659plo.99.2018.01.17.21.42.56 for (Google Transport Security); Wed, 17 Jan 2018 21:42:56 -0800 (PST) Date: Thu, 18 Jan 2018 14:42:51 +0900 From: Sergey Senozhatsky Subject: Re: [PATCH v5 0/2] printk: Console owner and waiter logic cleanup Message-ID: <20180118054251.GB6529@jagdpanzerIV> References: <20180111045817.GA494@jagdpanzerIV> <20180111093435.GA24497@linux.suse> <20180111103845.GB477@jagdpanzerIV> <20180111112908.50de440a@vmware.local.home> <20180111203057.5b1a8f8f@gandalf.local.home> <20180111215547.2f66a23a@gandalf.local.home> <20180116194456.GS3460072@devbig577.frc2.facebook.com> <20180117091208.ezvuhumnsarz5thh@pathway.suse.cz> <20180117151509.GT3460072@devbig577.frc2.facebook.com> <20180117121251.7283a56e@gandalf.local.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180117121251.7283a56e@gandalf.local.home> Sender: owner-linux-mm@kvack.org List-ID: To: Steven Rostedt Cc: Tejun Heo , Petr Mladek , Sergey Senozhatsky , Sergey Senozhatsky , akpm@linux-foundation.org, linux-mm@kvack.org, Cong Wang , Dave Hansen , Johannes Weiner , Mel Gorman , Michal Hocko , Vlastimil Babka , Peter Zijlstra , Linus Torvalds , Jan Kara , Mathieu Desnoyers , Tetsuo Handa , rostedt@home.goodmis.org, Byungchul Park , Pavel Machek , linux-kernel@vger.kernel.org On (01/17/18 12:12), Steven Rostedt wrote: [..] > /* > * Can we actually use the console at this time on this cpu? > @@ -2333,6 +2390,7 @@ void console_unlock(void) > > for (;;) { > struct printk_log *msg; > + bool offload; > size_t ext_len = 0; > size_t len; > > @@ -2393,15 +2451,20 @@ void console_unlock(void) > * waiter waiting to take over. > */ > console_lock_spinning_enable(); > + offload = recursion_check_start(); > > stop_critical_timings(); /* don't trace print latency */ > call_console_drivers(ext_text, ext_len, text, len); > start_critical_timings(); > > + recursion_check_finish(offload); > + > if (console_lock_spinning_disable_and_check()) { > printk_safe_exit_irqrestore(flags); > return; > } > + if (offload) > + kick_offload_thread(); > > printk_safe_exit_irqrestore(flags); ^^^^^^^^^^^^^^^^ but we call console drivers in printk_safe. printk -> console_drivers -> printk will be redirected to this-CPU printk_safe buffer. -ss -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. 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