Messages in this thread | | | Date | Tue, 3 Aug 2010 16:59:26 -0700 | From | Andrew Morton <> | Subject | Re: Additional fix : (was [v2]printk: fix delayed messages from CPU hotplug events) |
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On Tue, 3 Aug 2010 13:03:25 +0530 "Shilimkar, Santosh" <santosh.shilimkar@ti.com> wrote:
> > thought that those events simply aren't occurring, and that the patch > > has no effect. Confused - please explain further. > These events can come during the CPU hotplug(offline). Below is the > complete patch. Also attaching it in case some email format screw > up. > > ----------------------------------------------- > >From b99271ce43cc82cda28447444004933d0f218ee3 Mon Sep 17 00:00:00 2001 > From: Santosh Shilimkar <santosh.shilimkar@ti.com> > Date: Tue, 3 Aug 2010 12:58:22 +0530 > Subject: [PATCH] console: flush delayed log messages from cpu-hotplug events > > 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. > This is true even when CPU is getting hot-plugged out(offline) so > need to add additional hotplug events. > > The issue was seen on 2.6.34. > > Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com> > Signed-off-by: Kevin Cernekee <cernekee@gmail.com>
An older version of this patch is present in linux-next, committed by Paul Mundt, who wasn't cc'ed here(!).
Paul, please update. Be aware that the version of the patch to which I replied is also not the latest.
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