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>

3 files changed, 14 insertions, 0 deletions

diff --git a/include/linux/kmsg_dump.h b/include/linux/kmsg_dump.h
index 24b44145a886..2a0d7d651dc3 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 f64b8997fc76..0b0c9aa71e89 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 2745dcdb6c6c..31b71a276b40 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);