x86, microcode: Fix the failure path of microcode update driver init code

The microcode update driver's initialization code does not handle
failures correctly. This patch fixes this issue.

Signed-off-by: Jan Beulich <JBeulich@suse.com>
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/20111107123530.12164.31227.stgit@srivatsabhat.in.ibm.com
Link: http://lkml.kernel.org/r/4ED8E2270200007800065120@nat28.tlf.novell.com
Signed-off-by: Borislav Petkov <borislav.petkov@amd.com>

arch/x86/kernel/microcode_core.c

@@ -256,7 +256,7 @@ static int __init microcode_dev_init(void)
 	return 0;
 }
 
-static void microcode_dev_exit(void)
+static void __exit microcode_dev_exit(void)
 {
 	misc_deregister(&microcode_dev);
 }
@@ -519,10 +519,8 @@ static int __init microcode_init(void)
 
 	microcode_pdev = platform_device_register_simple("microcode", -1,
 							 NULL, 0);
-	if (IS_ERR(microcode_pdev)) {
-		microcode_dev_exit();
+	if (IS_ERR(microcode_pdev))
 		return PTR_ERR(microcode_pdev);
-	}
 
 	get_online_cpus();
 	mutex_lock(&microcode_mutex);
@@ -532,14 +530,12 @@ static int __init microcode_init(void)
 	mutex_unlock(&microcode_mutex);
 	put_online_cpus();
 
-	if (error) {
-		platform_device_unregister(microcode_pdev);
-		return error;
-	}
+	if (error)
+		goto out_pdev;
 
 	error = microcode_dev_init();
 	if (error)
-		return error;
+		goto out_sysdev_driver;
 
 	register_syscore_ops(&mc_syscore_ops);
 	register_hotcpu_notifier(&mc_cpu_notifier);
@@ -548,6 +544,20 @@ static int __init microcode_init(void)
 		" <tigran@aivazian.fsnet.co.uk>, Peter Oruba\n");
 
 	return 0;
+
+out_sysdev_driver:
+	get_online_cpus();
+	mutex_lock(&microcode_mutex);
+
+	sysdev_driver_unregister(&cpu_sysdev_class, &mc_sysdev_driver);
+
+	mutex_unlock(&microcode_mutex);
+	put_online_cpus();
+
+out_pdev:
+	platform_device_unregister(microcode_pdev);
+	return error;
+
 }
 module_init(microcode_init);