panic: resume console if panic after console suspend.

Device rebooted by kernel panic but no panic message.
This helps to get the panic messages in this case.

Bug: 10184128
Change-Id: I24545b1ce2f9e3e239795089d8564c2cc5f89fe7
Signed-off-by: shihhao.feng <shihhao.feng@lge.com>
Signed-off-by: Devin Kim <dojip.kim@lge.com>

include/linux/console.h

@@ -153,6 +153,7 @@ extern int braille_register_console(struct console *, int index,
 extern int braille_unregister_console(struct console *);
 extern void console_sysfs_notify(void);
 extern bool console_suspend_enabled;
+extern int is_console_suspended(void);
 
 /* Suspend and resume console messages over PM events */
 extern void suspend_console(void);

kernel/panic.c

@@ -24,6 +24,7 @@
 #include <linux/nmi.h>
 #include <linux/dmi.h>
 #include <linux/coresight.h>
+#include <linux/console.h>
 
 #define PANIC_TIMER_STEP 100
 #define PANIC_BLINK_SPD 18
@@ -133,6 +134,10 @@ void panic(const char *fmt, ...)
 
 	kmsg_dump(KMSG_DUMP_PANIC);
 
+	/* print last_kmsg even after console suspend */
+	if (is_console_suspended())
+		resume_console();
+
 	/*
 	 * Note smp_send_stop is the usual smp shutdown function, which
 	 * unfortunately means it may not be hardened to work in a panic

kernel/printk.c

@@ -1188,6 +1188,12 @@ module_param_named(console_suspend, console_suspend_enabled,
 MODULE_PARM_DESC(console_suspend, "suspend console during suspend"
 	" and hibernate operations");
 
+/* check current suspend/resume status of the console */
+int is_console_suspended(void)
+{
+	return console_suspended;
+}
+
 /**
  * suspend_console - suspend the console subsystem
  *