dtlk: fix error checks in module_init()

This patch fixes two things in module_init.

- fix register_chrdev() error check

Currently dtlk doesn't check register_chrdev() failure correctly.
register_chrdev() returns a errno on failure.

- check probe failure

dtlk ignores probe failure and allows the module loading without
such device. I got "Trying to free nonexistent resource" message
by release_region() when unloading module without device.

[[e-mail]: fix error code return]
Signed-off-by: Akinobu Mita <[e-mail]>
Cc: Chris Pallotta <[e-mail]>
Cc: Jim Van Zandt <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

drivers/char/dtlk.c

···
 
 static int __init dtlk_init(void)
 {
+	int err;
+
 	dtlk_port_lpc = 0;
 	dtlk_port_tts = 0;
 	dtlk_busy = 0;
 	dtlk_major = register_chrdev(0, "dtlk", &dtlk_fops);
-	if (dtlk_major == 0) {
+	if (dtlk_major < 0) {
 		printk(KERN_ERR "DoubleTalk PC - cannot register device\n");
-		return 0;
+		return dtlk_major;
 	}
-	if (dtlk_dev_probe() == 0)
-		printk(", MAJOR %d\n", dtlk_major);
+	err = dtlk_dev_probe();
+	if (err) {
+		unregister_chrdev(dtlk_major, "dtlk");
+		return err;
+	}
+	printk(", MAJOR %d\n", dtlk_major);
 
 	init_waitqueue_head(&dtlk_process_list);