(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(); > } > > > > Regards > Santosh _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
