[PATCH] fbdev: Fix crashes in various fbdev's blank routines

The backlight changes that went in had a bug where they could cause the
kernel to access an unitialized pointer when blanking if there is no
backlight control on a machine.

The bug affects atyfb, aty128fb, nvidiafb and rivafb.  radeonfb seems to
be ok.  This fixes it.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 3 insertions, 1 deletions

diff --git a/drivers/video/nvidia/nv_backlight.c b/drivers/video/nvidia/nv_backlight.c
index b45f577094ac..14c37c42191c 100644
--- a/drivers/video/nvidia/nv_backlight.c
+++ b/drivers/video/nvidia/nv_backlight.c
@@ -112,6 +112,8 @@ static struct backlight_properties nvidia_bl_data = {
 
 void nvidia_bl_set_power(struct fb_info *info, int power)
 {
+        if (info->bl_dev == NULL)
+                return;
         mutex_lock(&info->bl_mutex);
         up(&info->bl_dev->sem);
         info->bl_dev->props->power = power;
@@ -140,7 +142,7 @@ void nvidia_bl_init(struct nvidia_par *par)
         bd = backlight_device_register(name, par, &nvidia_bl_data);
         if (IS_ERR(bd)) {
                 info->bl_dev = NULL;
-                printk("nvidia: Backlight registration failed\n");
+                printk(KERN_WARNING "nvidia: Backlight registration failed\n");
                 goto error;
         }