2 files changed, 27 insertions, 10 deletions

diff --git a/arch/x86/include/asm/msr.h b/arch/x86/include/asm/msr.h
index 084ef95274cd..95203d40ffdd 100644
--- a/arch/x86/include/asm/msr.h
+++ b/arch/x86/include/asm/msr.h
@@ -169,7 +169,14 @@ static inline int wrmsr_safe(unsigned msr, unsigned low, unsigned high)
         return native_write_msr_safe(msr, low, high);
 }
 
-/* rdmsr with exception handling */
+/*
+ * rdmsr with exception handling.
+ *
+ * Please note that the exception handling works only after we've
+ * switched to the "smart" #GP handler in trap_init() which knows about
+ * exception tables - using this macro earlier than that causes machine
+ * hangs on boxes which do not implement the @msr in the first argument.
+ */
 #define rdmsr_safe(msr, p1, p2)                                 \
 ({                                                              \
         int __err;                                              \
diff --git a/arch/x86/kernel/microcode_core.c b/arch/x86/kernel/microcode_core.c
index f2d2a664e797..9d46f5e43b51 100644
--- a/arch/x86/kernel/microcode_core.c
+++ b/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);