[PATCH] loop: potential kernel hang waiting for kthread

Check that kernel_thread() succeeded, so we don't wait for something which
cannot happen.

Signed-off-by: Herbert Poetzl <herbert@13thfloor.at>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

drivers/block/loop.c

@@ -839,7 +839,9 @@ static int loop_set_fd(struct loop_device *lo, struct file *lo_file,
 
 	set_blocksize(bdev, lo_blocksize);
 
-	kernel_thread(loop_thread, lo, CLONE_KERNEL);
+	error = kernel_thread(loop_thread, lo, CLONE_KERNEL);
+	if (error < 0)
+		goto out_putf;
 	wait_for_completion(&lo->lo_done);
 	return 0;