Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755620Ab0GaLmp (ORCPT ); Sat, 31 Jul 2010 07:42:45 -0400 Received: from comal.ext.ti.com ([198.47.26.152]:37829 "EHLO comal.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754675Ab0GaLmn convert rfc822-to-8bit (ORCPT ); Sat, 31 Jul 2010 07:42:43 -0400 From: "Shilimkar, Santosh" To: Andrew Morton CC: King - ARM Linux , "linux-kernel@vger.kernel.org" , "Russell@smtp1.linux-foundation.org" , Kevin Cernekee , "linux-pm@lists.linux-foundation.org" Date: Sat, 31 Jul 2010 17:12:16 +0530 Subject: RE: [linux-pm] Additional fix : (was [v2]printk: fix delayed messages from CPU hotplug events) Thread-Topic: [linux-pm] Additional fix : (was [v2]printk: fix delayed messages from CPU hotplug events) Thread-Index: AcsXaGXicqa8+43jSDSUdKePtrVn0ABbO0yABfPtD3A= Message-ID: References: In-Reply-To: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: acceptlanguage: en-US Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3207 Lines: 83 Andrew, > -----Original Message----- > From: linux-pm-bounces@lists.linux-foundation.org [mailto:linux-pm- > bounces@lists.linux-foundation.org] On Behalf Of Shilimkar, Santosh > Sent: Thursday, July 01, 2010 9:58 AM > To: Kevin Cernekee; linux-pm@lists.linux-foundation.org > Cc: King - ARM Linux; linux-kernel@vger.kernel.org; Russell@smtp1.linux- > foundation.org > Subject: Re: [linux-pm] Additional fix : (was [v2]printk: fix delayed > messages from CPU hotplug events) > > (Adding linux-pm@lists.linux-foundation.org) > > > -----Original Message----- > > From: Shilimkar, Santosh > > Sent: Tuesday, June 29, 2010 2:22 PM > > To: 'Kevin Cernekee' > > Cc: linux-kernel@vger.kernel.org; Russell King - ARM Linux > > Subject: Additional fix : (was [v2]printk: fix delayed messages from CPU > > hotplug events) > > > > Hi, > > > > I have faced similar issue as what is being described in below with > > latest kernel. > > > > ------------------------------------------------ > > https://patchwork.kernel.org/patch/103347/ > > > > When a secondary CPU is being brought up, it is not uncommon for > > printk() to be invoked when cpu_online(smp_processor_id()) == 0. The > > case that I witnessed personally was on MIPS: > > > > http://lkml.org/lkml/2010/5/30/4 > > > > If (can_use_console() == 0), printk() will spool its output to log_buf > > and it will be visible in "dmesg", but that output will NOT be echoed to > > the console until somebody calls release_console_sem() from a CPU that > > is online. Therefore, the boot time messages from the new CPU can get > > stuck in "limbo" for a long time, and might suddenly appear on the > > screen when a completely unrelated event (e.g. "eth0: link is down") > > occurs. > > > > This patch modifies the console code so that any pending messages are > > automatically flushed out to the console whenever a CPU hotplug > > operation completes successfully or aborts. > > > > ----------------------------------------------- > > > > Above patch fixes only half of the problem. I mean the cpu online > > path prints are coming on the console. > > > > But similar problem also exist if there are prints in the cpu offline > > path. I got that fixed by adding below patch on top of you patch. > > > > diff --git a/kernel/printk.c b/kernel/printk.c > > index d370b74..f4d7352 100644 > > --- a/kernel/printk.c > > +++ b/kernel/printk.c > > @@ -982,6 +982,9 @@ static int __cpuinit console_cpu_notify(struct > > notifier_bloc > > switch (action) { > > case CPU_ONLINE: > > case CPU_UP_CANCELED: > > + case CPU_DEAD: > > + case CPU_DYING: > > + case CPU_DOWN_FAILED: > > if (try_acquire_console_sem() == 0) > > release_console_sem(); > > } > > > > Haven't seen any comment on the original patch and this additional fix. Patch as such is straight forward and useful. Can you please have a look at it, if its ok. Regards, Santosh -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/