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
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Subject: console: flush log messages for more cpu-hotplug events
From: "Shilimkar, Santosh" <santosh.shilimkar@xxxxxx>
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 <cernekee@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
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@xxxxxx are
linux-next.patch
console-flush-log-messages-for-more-cpu-hotplug-events.patch
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