From mboxrd@z Thu Jan 1 00:00:00 1970 From: akpm@linux-foundation.org Subject: + console-flush-log-messages-for-more-cpu-hotplug-events.patch added to -mm tree Date: Mon, 02 Aug 2010 15:44:39 -0700 Message-ID: <201008022244.o72MidQg015824@imap1.linux-foundation.org> Reply-To: linux-kernel@vger.kernel.org Return-path: Received: from smtp1.linux-foundation.org ([140.211.169.13]:38299 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754053Ab0HBWon (ORCPT ); Mon, 2 Aug 2010 18:44:43 -0400 Sender: mm-commits-owner@vger.kernel.org List-Id: mm-commits@vger.kernel.org To: mm-commits@vger.kernel.org Cc: santosh.shilimkar@ti.com, cernekee@gmail.com The patch titled console: flush log messages for more cpu-hotplug events has been added to the -mm tree. Its filename is console-flush-log-messages-for-more-cpu-hotplug-events.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find out what to do about this The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: console: flush log messages for more cpu-hotplug events From: "Shilimkar, Santosh" 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. Cc: Kevin Cernekee Signed-off-by: Andrew Morton --- kernel/printk.c | 3 +++ 1 file changed, 3 insertions(+) diff -puN kernel/printk.c~console-flush-log-messages-for-more-cpu-hotplug-events kernel/printk.c --- a/kernel/printk.c~console-flush-log-messages-for-more-cpu-hotplug-events +++ a/kernel/printk.c @@ -1003,6 +1003,9 @@ static int __cpuinit console_cpu_notify( switch (action) { case CPU_ONLINE: case CPU_UP_CANCELED: + case CPU_DEAD: + case CPU_DYING: + case CPU_DOWN_FAILED: acquire_console_sem(); release_console_sem(); } _ Patches currently in -mm which might be from santosh.shilimkar@ti.com are linux-next.patch console-flush-log-messages-for-more-cpu-hotplug-events.patch