From 04c6862c055fb687c90d9652f32c11a063df15cf Mon Sep 17 00:00:00 2001
From: Seiji Aguchi <seiji.aguchi@hds.com>
Date: Wed, 12 Jan 2011 16:59:30 -0800
Subject: [PATCH] kmsg_dump: add kmsg_dump() calls to the reboot, halt,
 poweroff and emergency_restart paths

We need to know the reason why system rebooted in support service.
However, we can't inform our customers of the reason because final
messages are lost on current Linux kernel.

This patch improves the situation above because the final messages are
saved by adding kmsg_dump() to reboot, halt, poweroff and
emergency_restart path.

Signed-off-by: Seiji Aguchi <seiji.aguchi@hds.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Marco Stornelli <marco.stornelli@gmail.com>
Reviewed-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 include/linux/kmsg_dump.h | 4 ++++
 kernel/printk.c           | 4 ++++
 kernel/sys.c              | 6 ++++++
 3 files changed, 14 insertions(+)

diff --git a/include/linux/kmsg_dump.h b/include/linux/kmsg_dump.h
index 24b44145a886f7..2a0d7d651dc34f 100644
--- a/include/linux/kmsg_dump.h
+++ b/include/linux/kmsg_dump.h
@@ -18,6 +18,10 @@ enum kmsg_dump_reason {
 	KMSG_DUMP_OOPS,
 	KMSG_DUMP_PANIC,
 	KMSG_DUMP_KEXEC,
+	KMSG_DUMP_RESTART,
+	KMSG_DUMP_HALT,
+	KMSG_DUMP_POWEROFF,
+	KMSG_DUMP_EMERG,
 };
 
 /**
diff --git a/kernel/printk.c b/kernel/printk.c
index f64b8997fc768f..0b0c9aa71e89a5 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -1539,6 +1539,10 @@ static const char * const kmsg_reasons[] = {
 	[KMSG_DUMP_OOPS]	= "oops",
 	[KMSG_DUMP_PANIC]	= "panic",
 	[KMSG_DUMP_KEXEC]	= "kexec",
+	[KMSG_DUMP_RESTART]	= "restart",
+	[KMSG_DUMP_HALT]	= "halt",
+	[KMSG_DUMP_POWEROFF]	= "poweroff",
+	[KMSG_DUMP_EMERG]	= "emergency_restart",
 };
 
 static const char *kmsg_to_str(enum kmsg_dump_reason reason)
diff --git a/kernel/sys.c b/kernel/sys.c
index 2745dcdb6c6c57..31b71a276b40ed 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -43,6 +43,8 @@
 #include <linux/kprobes.h>
 #include <linux/user_namespace.h>
 
+#include <linux/kmsg_dump.h>
+
 #include <asm/uaccess.h>
 #include <asm/io.h>
 #include <asm/unistd.h>
@@ -285,6 +287,7 @@ SYSCALL_DEFINE2(getpriority, int, which, int, who)
  */
 void emergency_restart(void)
 {
+	kmsg_dump(KMSG_DUMP_EMERG);
 	machine_emergency_restart();
 }
 EXPORT_SYMBOL_GPL(emergency_restart);
@@ -312,6 +315,7 @@ void kernel_restart(char *cmd)
 		printk(KERN_EMERG "Restarting system.\n");
 	else
 		printk(KERN_EMERG "Restarting system with command '%s'.\n", cmd);
+	kmsg_dump(KMSG_DUMP_RESTART);
 	machine_restart(cmd);
 }
 EXPORT_SYMBOL_GPL(kernel_restart);
@@ -333,6 +337,7 @@ void kernel_halt(void)
 	kernel_shutdown_prepare(SYSTEM_HALT);
 	sysdev_shutdown();
 	printk(KERN_EMERG "System halted.\n");
+	kmsg_dump(KMSG_DUMP_HALT);
 	machine_halt();
 }
 
@@ -351,6 +356,7 @@ void kernel_power_off(void)
 	disable_nonboot_cpus();
 	sysdev_shutdown();
 	printk(KERN_EMERG "Power down.\n");
+	kmsg_dump(KMSG_DUMP_POWEROFF);
 	machine_power_off();
 }
 EXPORT_SYMBOL_GPL(kernel_power_off);