Andrew, > -----Original Message----- > From: linux-pm-bounces@xxxxxxxxxxxxxxxxxxxxxxxxxx [mailto:linux-pm- > bounces@xxxxxxxxxxxxxxxxxxxxxxxxxx] On Behalf Of Shilimkar, Santosh > Sent: Thursday, July 01, 2010 9:58 AM > To: Kevin Cernekee; linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx > Cc: King - ARM Linux; linux-kernel@xxxxxxxxxxxxxxx; Russell@xxxxxxxxxxxx > foundation.org > Subject: Re: Additional fix : (was [v2]printk: fix delayed > messages from CPU hotplug events) > > (Adding linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx) > > > -----Original Message----- > > From: Shilimkar, Santosh > > Sent: Tuesday, June 29, 2010 2:22 PM > > To: 'Kevin Cernekee' > > Cc: linux-kernel@xxxxxxxxxxxxxxx; 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 _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
