From: Robin Getz <rgetz@blackfin.uclinux.org>

Gerd Hoffmann pointed out that my patch from yesterday can lead to a null
pointer dereference if the kernel is booted with no console, and no
earlyprintk defined.  This fixes that issue.

Signed-off-by: Robin Getz <rgetz@blackfin.uclinux.org>
Cc: "Gerd Hoffmann" <kraxel@redhat.com>
Cc: "Paul Mundt" <lethal@linux-sh.org>
Cc: Mike Frysinger <vapier.adi@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 kernel/printk.c |   10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff -puN kernel/printk.c~fix-ensure-we-dont-use-bootconsoles-after-init-has-been-released kernel/printk.c
--- a/kernel/printk.c~fix-ensure-we-dont-use-bootconsoles-after-init-has-been-released
+++ a/kernel/printk.c
@@ -1085,10 +1085,12 @@ EXPORT_SYMBOL(unregister_console);
 
 static int __init disable_boot_consoles(void)
 {
-	if (console_drivers->flags & CON_BOOT) {
-		printk(KERN_INFO "turn off boot console %s%d\n",
-			console_drivers->name, console_drivers->index);
-		return unregister_console(console_drivers);
+	if (console_drivers != NULL) {
+		if (console_drivers->flags & CON_BOOT) {
+			printk(KERN_INFO "turn off boot console %s%d\n",
+				console_drivers->name, console_drivers->index);
+			return unregister_console(console_drivers);
+		}
 	}
 	return 0;
 }
_