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 136f263ed47b79d010cf4ca06e7b1e2a07e4fd73..ecb2d6693f584fc3760ab287c8fcc644cf6d7725 100644 (file)
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1819,6 +1819,15 @@ 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/process.c b/arch/arm/kernel/process.c
index b18bd2f91d649c7e6c748897b5f2ec748660e140..185f5b7e6947b98a1a3fe1ccbac21a69c5dba063 100644 (file)
--- a/arch/arm/kernel/process.c
+++ b/arch/arm/kernel/process.c
@@ -32,6 +32,7 @@
 #include <linux/hw_breakpoint.h>
 #include <linux/cpuidle.h>
 #include <linux/leds.h>
+#include <linux/console.h>
 
 #include <asm/cacheflush.h>
 #include <asm/idmap.h>
@@ -60,6 +61,31 @@ static const char *isa_modes[] = {
 extern void call_with_stack(void (*fn)(void *), void *arg, void *sp);
 typedef void (*phys_reset_t)(unsigned long);
 
+#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
+
 /*
  * A temporary stack to use for CPU reset. This is static so that we
  * don't clobber it with the identity mapping. When running with this
@@ -240,6 +266,10 @@ void machine_restart(char *cmd)
 {
        smp_send_stop();
 
+       /* Flush the console to make sure all the relevant messages make it
+        * out to the console drivers */
+       arm_machine_flush_console();
+
        arm_pm_restart(reboot_mode, cmd);
 
        /* Give a grace period for failure to restart of 1s */