ARM: add option to flush console before reboot

If the console_lock was held while the system was rebooted, the messages
in the temporary logbuffer would not have propogated to all the console
drivers.

This force releases the console lock if it failed to be acquired.

Change-Id: I193dcf7b968be17966833e50b8b8bc70d5d9fe89
Signed-off-by: Dima Zavin <dima@android.com>

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 34e1569a11ee322a0a020bdfe0c9b801b6b58c12..88a56444749a61f0a120f13519e77ab7e401f70e 100644 (file)
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1816,6 +1816,15 @@ config XEN
        help
          Say Y if you want to run Linux in a Virtual Machine on Xen on ARM.
 
+config ARM_FLUSH_CONSOLE_ON_RESTART
+       bool "Force flush the console on restart"
+       help
+         If the console is locked while the system is rebooted, the messages
+         in the temporary logbuffer would not have propogated to all the
+         console drivers. This option forces the console lock to be
+         released if it failed to be acquired, which will cause all the
+         pending messages to be flushed.
+
 endmenu
 
 menu "Boot options"

diff --git a/arch/arm/kernel/reboot.c b/arch/arm/kernel/reboot.c
index 38269358fd252c6bb93fd58a0478319c436cdfd3..1a06da8f0366d9b1056f220c26d9386219f09c60 100644 (file)
--- a/arch/arm/kernel/reboot.c
+++ b/arch/arm/kernel/reboot.c
@@ -6,6 +6,7 @@
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
  */
+#include <linux/console.h>
 #include <linux/cpu.h>
 #include <linux/delay.h>
 #include <linux/reboot.h>
@@ -124,6 +125,31 @@ void machine_power_off(void)
                pm_power_off();
 }
 
+#ifdef CONFIG_ARM_FLUSH_CONSOLE_ON_RESTART
+void arm_machine_flush_console(void)
+{
+       printk("\n");
+       pr_emerg("Restarting %s\n", linux_banner);
+       if (console_trylock()) {
+               console_unlock();
+               return;
+       }
+
+       mdelay(50);
+
+       local_irq_disable();
+       if (!console_trylock())
+               pr_emerg("arm_restart: Console was locked! Busting\n");
+       else
+               pr_emerg("arm_restart: Console was locked!\n");
+       console_unlock();
+}
+#else
+void arm_machine_flush_console(void)
+{
+}
+#endif
+
 /*
  * Restart requires that the secondary CPUs stop performing any activity
  * while the primary CPU resets the system. Systems with a single CPU can
@@ -140,6 +166,10 @@ void machine_restart(char *cmd)
        local_irq_disable();
        smp_send_stop();
 
+       /* Flush the console to make sure all the relevant messages make it
+        * out to the console drivers */
+       arm_machine_flush_console();
+
        if (arm_pm_restart)
                arm_pm_restart(reboot_mode, cmd);
        else