[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>

2 files changed, 8 insertions, 2 deletions

diff --git a/drivers/video/aty/aty128fb.c b/drivers/video/aty/aty128fb.c
index 3e827e04a2aa..106d428b72c9 100644
--- a/drivers/video/aty/aty128fb.c
+++ b/drivers/video/aty/aty128fb.c
@@ -1800,6 +1800,9 @@ static struct backlight_properties aty128_bl_data = {
 
 static void aty128_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;
@@ -1828,7 +1831,7 @@ static void aty128_bl_init(struct aty128fb_par *par)
         bd = backlight_device_register(name, par, &aty128_bl_data);
         if (IS_ERR(bd)) {
                 info->bl_dev = NULL;
-                printk("aty128: Backlight registration failed\n");
+                printk(KERN_WARNING "aty128: Backlight registration failed\n");
                 goto error;
         }
 
diff --git a/drivers/video/aty/atyfb_base.c b/drivers/video/aty/atyfb_base.c
index 053ff63365b7..510e4ea296ed 100644
--- a/drivers/video/aty/atyfb_base.c
+++ b/drivers/video/aty/atyfb_base.c
@@ -2199,6 +2199,9 @@ static struct backlight_properties aty_bl_data = {
 
 static void aty_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;
@@ -2223,7 +2226,7 @@ static void aty_bl_init(struct atyfb_par *par)
         bd = backlight_device_register(name, par, &aty_bl_data);
         if (IS_ERR(bd)) {
                 info->bl_dev = NULL;
-                printk("aty: Backlight registration failed\n");
+                printk(KERN_WARNING "aty: Backlight registration failed\n");
                 goto error;
         }