Commit abe43400 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

perf: Sysfs enumeration 



Simple sysfs emumeration of the PMUs.

Use a "event_source" bus, and add PMU devices using their name.

Each PMU device has a type attribute which contrains the value needed
for perf_event_attr::type to identify this PMU.

This is the minimal stub needed to start using this interface,
we'll consider extending the sysfs usage later.

Cc: Kay Sievers <kay.sievers@vrfy.org>
Cc: Greg KH <gregkh@suse.de>
Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <20101117222056.316982569@chello.nl>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 2e80a82a

include/linux/perf_event.h

+1 −0
Original line number Diff line number Diff line
@@ -588,6 +588,7 @@ struct perf_event; 
struct pmu {

	struct list_head		entry;



	struct device			*dev;

	char				*name;

	int				type;

kernel/perf_event.c

+94 −1
Original line number Diff line number Diff line
@@ -24,6 +24,7 @@ 
#include <linux/ptrace.h>

#include <linux/reboot.h>

#include <linux/vmstat.h>

#include <linux/device.h>

#include <linux/vmalloc.h>

#include <linux/hardirq.h>

#include <linux/rculist.h>
@@ -5308,6 +5309,58 @@ out: 
}

static struct idr pmu_idr;



static ssize_t

type_show(struct device *dev, struct device_attribute *attr, char *page)

{

	struct pmu *pmu = dev_get_drvdata(dev);



	return snprintf(page, PAGE_SIZE-1, "%d\n", pmu->type);

}



static struct device_attribute pmu_dev_attrs[] = {

       __ATTR_RO(type),

       __ATTR_NULL,

};



static int pmu_bus_running;

static struct bus_type pmu_bus = {

	.name		= "event_source",

	.dev_attrs	= pmu_dev_attrs,

};



static void pmu_dev_release(struct device *dev)

{

	kfree(dev);

}



static int pmu_dev_alloc(struct pmu *pmu)

{

	int ret = -ENOMEM;



	pmu->dev = kzalloc(sizeof(struct device), GFP_KERNEL);

	if (!pmu->dev)

		goto out;



	device_initialize(pmu->dev);

	ret = dev_set_name(pmu->dev, "%s", pmu->name);

	if (ret)

		goto free_dev;



	dev_set_drvdata(pmu->dev, pmu);

	pmu->dev->bus = &pmu_bus;

	pmu->dev->release = pmu_dev_release;

	ret = device_add(pmu->dev);

	if (ret)

		goto free_dev;



out:

	return ret;



free_dev:

	put_device(pmu->dev);

	goto out;

}



int perf_pmu_register(struct pmu *pmu, char *name, int type)

{

	int cpu, ret;
@@ -5336,6 +5389,12 @@ int perf_pmu_register(struct pmu *pmu, char *name, int type) 
	}

	pmu->type = type;



	if (pmu_bus_running) {

		ret = pmu_dev_alloc(pmu);

		if (ret)

			goto free_idr;

	}



skip_type:

	pmu->pmu_cpu_context = find_pmu_context(pmu->task_ctx_nr);

	if (pmu->pmu_cpu_context)
@@ -5343,7 +5402,7 @@ skip_type: 


	pmu->pmu_cpu_context = alloc_percpu(struct perf_cpu_context);

	if (!pmu->pmu_cpu_context)

		goto free_ird;

		goto free_dev;



	for_each_possible_cpu(cpu) {

		struct perf_cpu_context *cpuctx;
@@ -5387,6 +5446,10 @@ unlock: 


	return ret;



free_dev:

	device_del(pmu->dev);

	put_device(pmu->dev);



free_idr:

	if (pmu->type >= PERF_TYPE_MAX)

		idr_remove(&pmu_idr, pmu->type);
@@ -5412,6 +5475,8 @@ void perf_pmu_unregister(struct pmu *pmu) 
	free_percpu(pmu->pmu_disable_count);

	if (pmu->type >= PERF_TYPE_MAX)

		idr_remove(&pmu_idr, pmu->type);

	device_del(pmu->dev);

	put_device(pmu->dev);

	free_pmu_context(pmu);

}
@@ -6603,3 +6668,31 @@ void __init perf_event_init(void) 
	ret = init_hw_breakpoint();

	WARN(ret, "hw_breakpoint initialization failed with: %d", ret);

}



static int __init perf_event_sysfs_init(void)

{

	struct pmu *pmu;

	int ret;



	mutex_lock(&pmus_lock);



	ret = bus_register(&pmu_bus);

	if (ret)

		goto unlock;



	list_for_each_entry(pmu, &pmus, entry) {

		if (!pmu->name || pmu->type < 0)

			continue;



		ret = pmu_dev_alloc(pmu);

		WARN(ret, "Failed to register pmu: %s, reason %d\n", pmu->name, ret);

	}

	pmu_bus_running = 1;

	ret = 0;



unlock:

	mutex_unlock(&pmus_lock);



	return ret;

}

device_initcall(perf_event_sysfs_init);

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