linux-kernel - [RFC][Patch] Adding kmsg_dump() to reboot/halt/poweroff/emergency

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Date:	Mon, 18 Oct 2010 18:24:11 -0400
From:	Seiji Aguchi <seiji.aguchi@....com>
To:	"simon.kagstrom@...insight.net" <simon.kagstrom@...insight.net>,
	"David.Woodhouse@...el.com" <David.Woodhouse@...el.com>,
	"anders.grafstrom@...insight.net" <anders.grafstrom@...insight.net>,
	"Artem.Bityutskiy@...ia.com" <Artem.Bityutskiy@...ia.com>,
	"kosaki.motohiro@...fujitsu.com" <kosaki.motohiro@...fujitsu.com>,
	"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
	"jason.wessel@...driver.com" <jason.wessel@...driver.com>,
	"jslaby@...e.cz" <jslaby@...e.cz>,
	"jmorris@...ei.org" <jmorris@...ei.org>,
	"eparis@...hat.com" <eparis@...hat.com>, "hch@....de" <hch@....de>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:	"dle-develop@...ts.sourceforge.net" 
	<dle-develop@...ts.sourceforge.net>,
	Satoru Moriya <satoru.moriya@....com>
Subject: [RFC][Patch] Adding kmsg_dump() to
 reboot/halt/poweroff/emergency_restart path

Hi,

Final messages from reboot, halt and poweroff aren't output to disk because klogd/syslogd 
has been killed and root file system has been turned read-only.

Final messages from emergency_restart aren't output to disk as well because system may
reboot before klogd/syslogd outputs messages to disk.

Therefore, it is better to put kmsg_dumper in reboot/halt/poweroff/emergency_restart path.
Any comments/advices are welcome.

Seiji

 Signed-off-by: Seiji Aguchi <seiji.aguchi@....com>

---
 include/linux/kmsg_dump.h |    4 ++++
 kernel/printk.c           |    4 ++++
 kernel/sys.c              |    6 ++++++
 3 files changed, 14 insertions(+), 0 deletions(-)

diff --git a/include/linux/kmsg_dump.h b/include/linux/kmsg_dump.h
index 24b4414..2a0d7d6 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 6d6b09f..6a63848 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -1516,6 +1516,10 @@ 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 7f5a0cd..3eab886 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 @@ out_unlock:
  */
 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);
-- 
1.7.2.2

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