video:uvesafb: notice user when we failed to save hardware state

uvesafb_open may failed to save hardware state when kmalloc failed
in uvesafb_vbe_state_save, we should check this and notice user.
Signed-off-by: Wang YanQing <udknight@gmail.com>
Signed-off-by: Florian Tobias Schandinat <FlorianSchandinat@gmx.de>

drivers/video/uvesafb.c

@@ -363,7 +363,7 @@ static u8 *uvesafb_vbe_state_save(struct uvesafb_par *par)
 
 	state = kmalloc(par->vbe_state_size, GFP_KERNEL);
 	if (!state)
-		return NULL;
+		return ERR_PTR(-ENOMEM);
 
 	task = uvesafb_prep();
 	if (!task) {
@@ -1180,9 +1180,17 @@ static int uvesafb_open(struct fb_info *info, int user)
 {
 	struct uvesafb_par *par = info->par;
 	int cnt = atomic_read(&par->ref_count);
+	u8 *buf = NULL;
 
-	if (!cnt && par->vbe_state_size)
-		par->vbe_state_orig = uvesafb_vbe_state_save(par);
+	if (!cnt && par->vbe_state_size) {
+		buf =  uvesafb_vbe_state_save(par);
+		if (IS_ERR(buf)) {
+			printk(KERN_WARNING "uvesafb: save hardware state"
+				"failed, error code is %ld!\n", PTR_ERR(buf));
+		} else {
+			par->vbe_state_orig = buf;
+		}
+	}
 
 	atomic_inc(&par->ref_count);
 	return 0;