x86/perf/intel/cstate: Modularize driver

Add the exit function and allow the driver to be built as a module.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Link: http://lkml.kernel.org/r/20160320185623.658869675@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/Kconfig.perf

@@ -16,4 +16,12 @@ config PERF_EVENTS_INTEL_RAPL
 	Include support for Intel rapl performance events for power
 	monitoring on modern processors.
 
+config PERF_EVENTS_INTEL_CSTATE
+	tristate "Intel cstate performance events"
+	depends on PERF_EVENTS && CPU_SUP_INTEL && PCI
+	default y
+	---help---
+	Include support for Intel cstate performance events for power
+	monitoring on modern processors.
+
 endmenu

arch/x86/events/intel/Makefile

@@ -1,7 +1,9 @@
 obj-$(CONFIG_CPU_SUP_INTEL)		+= core.o bts.o cqm.o
-obj-$(CONFIG_CPU_SUP_INTEL)		+= cstate.o ds.o knc.o
+obj-$(CONFIG_CPU_SUP_INTEL)		+= ds.o knc.o
 obj-$(CONFIG_CPU_SUP_INTEL)		+= lbr.o p4.o p6.o pt.o
 obj-$(CONFIG_PERF_EVENTS_INTEL_RAPL)	+= intel-rapl.o
 intel-rapl-objs				:= rapl.o
 obj-$(CONFIG_PERF_EVENTS_INTEL_UNCORE)	+= intel-uncore.o
 intel-uncore-objs			:= uncore.o uncore_nhmex.o uncore_snb.o uncore_snbep.o
+obj-$(CONFIG_PERF_EVENTS_INTEL_CSTATE)	+= intel-cstate.o
+intel-cstate-objs			:= cstate.o

arch/x86/events/intel/cstate.c

@@ -91,6 +91,8 @@
 #include <asm/cpu_device_id.h>
 #include "../perf_event.h"
 
+MODULE_LICENSE("GPL");
+
 #define DEFINE_CSTATE_FORMAT_ATTR(_var, _name, _format)		\
 static ssize_t __cstate_##_var##_show(struct kobject *kobj,	\
 				struct kobj_attribute *attr,	\
@@ -432,6 +434,11 @@ static int cstate_cpu_notifier(struct notifier_block *self,
 	return NOTIFY_OK;
 }
 
+static struct notifier_block cstate_cpu_nb = {
+	.notifier_call	= cstate_cpu_notifier,
+	.priority       = CPU_PRI_PERF + 1,
+};
+
 static struct pmu cstate_core_pmu = {
 	.attr_groups	= core_attr_groups,
 	.name		= "cstate_core",
@@ -581,7 +588,7 @@ static int __init cstate_probe(const struct cstate_model *cm)
 	return (has_cstate_core || has_cstate_pkg) ? 0 : -ENODEV;
 }
 
-static void __init cstate_cleanup(void)
+static inline void cstate_cleanup(void)
 {
 	if (has_cstate_core)
 		perf_pmu_unregister(&cstate_core_pmu);
@@ -616,7 +623,7 @@ static int __init cstate_init(void)
 			goto out;
 		}
 	}
-	__perf_cpu_notifier(cstate_cpu_notifier);
+	__register_cpu_notifier(&cstate_cpu_nb);
 out:
 	cpu_notifier_register_done();
 	return err;
@@ -640,4 +647,13 @@ static int __init cstate_pmu_init(void)
 
 	return cstate_init();
 }
-device_initcall(cstate_pmu_init);
+module_init(cstate_pmu_init);
+
+static void __exit cstate_pmu_exit(void)
+{
+	cpu_notifier_register_begin();
+	__unregister_cpu_notifier(&cstate_cpu_nb);
+	cstate_cleanup();
+	cpu_notifier_register_done();
+}
+module_exit(cstate_pmu_exit);