x86/mce: Improve mcheck_init_device() error handling

Check return code of every function called by mcheck_init_device().

Signed-off-by: Mathieu Souchaud <mattieu.souchaud@free.fr>
Link: http://lkml.kernel.org/r/1399151031-19905-1-git-send-email-mattieu.souchaud@free.fr
Signed-off-by: Borislav Petkov <bp@suse.de>

arch/x86/kernel/cpu/mcheck/mce.c

@@ -2437,32 +2437,65 @@ static __init int mcheck_init_device(void)
 	int err;
 	int i = 0;
 
-	if (!mce_available(&boot_cpu_data))
-		return -EIO;
+	if (!mce_available(&boot_cpu_data)) {
+		err = -EIO;
+		goto err_out;
+	}
 
-	zalloc_cpumask_var(&mce_device_initialized, GFP_KERNEL);
+	if (!zalloc_cpumask_var(&mce_device_initialized, GFP_KERNEL)) {
+		err = -ENOMEM;
+		goto err_out;
+	}
 
 	mce_init_banks();
 
 	err = subsys_system_register(&mce_subsys, NULL);
 	if (err)
-		return err;
+		goto err_out_mem;
 
 	cpu_notifier_register_begin();
 	for_each_online_cpu(i) {
 		err = mce_device_create(i);
 		if (err) {
 			cpu_notifier_register_done();
-			return err;
+			goto err_device_create;
 		}
 	}
 
-	register_syscore_ops(&mce_syscore_ops);
 	__register_hotcpu_notifier(&mce_cpu_notifier);
 	cpu_notifier_register_done();
 
+	register_syscore_ops(&mce_syscore_ops);
+
 	/* register character device /dev/mcelog */
-	misc_register(&mce_chrdev_device);
+	err = misc_register(&mce_chrdev_device);
+	if (err)
+		goto err_register;
+
+	return 0;
+
+err_register:
+	unregister_syscore_ops(&mce_syscore_ops);
+
+	cpu_notifier_register_begin();
+	__unregister_hotcpu_notifier(&mce_cpu_notifier);
+	cpu_notifier_register_done();
+
+err_device_create:
+	/*
+	 * We didn't keep track of which devices were created above, but
+	 * even if we had, the set of online cpus might have changed.
+	 * Play safe and remove for every possible cpu, since
+	 * mce_device_remove() will do the right thing.
+	 */
+	for_each_possible_cpu(i)
+		mce_device_remove(i);
+
+err_out_mem:
+	free_cpumask_var(mce_device_initialized);
+
+err_out:
+	pr_err("Unable to init device /dev/mcelog (rc: %d)\n", err);
 
 	return err;
 }