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>

1 files changed, 30 insertions, 0 deletions

diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
index 148625de8e4d..24e7e5722f1c 100644
--- a/arch/arm/kernel/process.c
+++ b/arch/arm/kernel/process.c
@@ -31,6 +31,7 @@
 #include <linux/random.h>
 #include <linux/hw_breakpoint.h>
 #include <linux/cpuidle.h>
+#include <linux/console.h>
 
 #include <asm/cacheflush.h>
 #include <asm/processor.h>
@@ -91,8 +92,37 @@ static int __init hlt_setup(char *__unused)
 __setup("nohlt", nohlt_setup);
 __setup("hlt", hlt_setup);
 
+#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
+
 void arm_machine_restart(char mode, const char *cmd)
 {
+	/* Flush the console to make sure all the relevant messages make it
+	 * out to the console drivers */
+	arm_machine_flush_console();
+
 	/* Disable interrupts first */
 	local_irq_disable();
 	local_fiq_disable();