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@peo3
Created Jun 23, 2012
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cgroup LKM example
/*
* cgroup-notifier-counter.c
*
* Author : peo3
*
* Based on cgroup_freezer.c
*
* Copyright IBM Corporation, 2007
*
* Author : Cedric Le Goater <clg@fr.ibm.com>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of version 2.1 of the GNU Lesser General Public License
* as published by the Free Software Foundation.
*
* This program is distributed in the hope that it would be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
*/
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/cgroup.h>
#include <linux/notifier.h>
#include <linux/preempt.h>
#include <linux/kdebug.h>
extern struct cgroup_subsys notifier_subsys;
#define notifier_subsys_id notifier_subsys.subsys_id
enum notifier_types {
NOTIFIER_PREEMPT = 0,
NOTIFIER_DIE,
NOTIFIER_TYPES,
};
struct notifier {
struct cgroup_subsys_state css;
u64 counters[NOTIFIER_TYPES];
spinlock_t lock; /* protects _writes_ to state */
};
static inline struct notifier *cgroup_notifier(
struct cgroup *cgroup)
{
return container_of(
cgroup_subsys_state(cgroup, notifier_subsys_id),
struct notifier, css);
}
static inline struct notifier *task_notifier(struct task_struct *task)
{
return container_of(task_subsys_state(task, notifier_subsys_id),
struct notifier, css);
}
static struct cgroup_subsys_state *notifier_create(struct cgroup_subsys *ss, struct cgroup *cgroup)
{
struct notifier *notifier;
int i;
notifier = kzalloc(sizeof(struct notifier), GFP_KERNEL);
if (!notifier)
return ERR_PTR(-ENOMEM);
spin_lock_init(&notifier->lock);
for (i=0; i < NOTIFIER_TYPES; i++)
notifier->counters[i] = 0;
return &notifier->css;
}
static void notifier_destroy(struct cgroup_subsys *ss, struct cgroup *cgroup)
{
struct notifier *notifier = cgroup_notifier(cgroup);
kfree(notifier);
}
static u64 notifier_read_u64(struct cgroup *cgroup, struct cftype *cft)
{
u64 ret;
struct notifier *notifier = cgroup_notifier(cgroup);
enum notifier_types type = cft->private;
spin_lock(&notifier->lock);
ret = notifier->counters[type];
spin_unlock(&notifier->lock);
return ret;
}
static struct cftype files[] = {
{
.name = "preempt",
.private = NOTIFIER_PREEMPT,
.read_u64 = notifier_read_u64,
},
{
.name = "die",
.private = NOTIFIER_DIE,
.read_u64 = notifier_read_u64,
},
};
static int notifier_populate(struct cgroup_subsys *ss, struct cgroup *cgroup)
{
if (!cgroup->parent)
return 0;
return cgroup_add_files(cgroup, ss, files, ARRAY_SIZE(files));
}
struct cgroup_subsys notifier_subsys = {
.name = "notifier_counter",
.create = notifier_create,
.destroy = notifier_destroy,
.populate = notifier_populate,
.use_id = 1,
.module = THIS_MODULE,
};
static __read_mostly struct preempt_ops notifier_preempt_ops;
static struct preempt_notifier preempt_notifier;
static int
notifier_call_die(struct notifier_block *self, unsigned long cmd, void *ptr)
{
struct notifier *notifier = task_notifier(get_current());
struct cgroup *cgroup = task_cgroup(get_current(), notifier_subsys_id);
if (!cgroup->parent)
return 0;
spin_lock(&notifier->lock);
notifier->counters[NOTIFIER_DIE] += 1;
spin_unlock(&notifier->lock);
return 0;
}
static struct notifier_block notifier_block_die = {
.notifier_call = notifier_call_die,
};
static void notifier_sched_in(struct preempt_notifier *pn, int cpu)
{
}
static void notifier_sched_out(struct preempt_notifier *pn, struct task_struct *next)
{
struct notifier *notifier = task_notifier(next);
struct cgroup *cgroup = task_cgroup(next, notifier_subsys_id);
if (!cgroup->parent)
return;
spin_lock(&notifier->lock);
notifier->counters[NOTIFIER_PREEMPT] += 1;
spin_unlock(&notifier->lock);
}
static int __init init_cgroup_notifier(void)
{
int ret = cgroup_load_subsys(&notifier_subsys);
if (ret)
return ret;
notifier_preempt_ops.sched_in = notifier_sched_in;
notifier_preempt_ops.sched_out = notifier_sched_out;
preempt_notifier_init(&preempt_notifier, &notifier_preempt_ops);
preempt_notifier_register(&preempt_notifier);
register_die_notifier(&notifier_block_die);
return ret;
}
static void __exit exit_cgroup_notifier(void)
{
preempt_notifier_unregister(&preempt_notifier);
cgroup_unload_subsys(&notifier_subsys);
unregister_die_notifier(&notifier_block_die);
}
module_init(init_cgroup_notifier);
module_exit(exit_cgroup_notifier);
MODULE_LICENSE("GPL");
obj-m = cgroup-notifier-counter.o
KVERSION = $(shell uname -r)
all:
make -C /lib/modules/$(KVERSION)/build M=$(PWD) modules
clean:
make -C /lib/modules/$(KVERSION)/build M=$(PWD) clean
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