root/samples/markers/probe-example.c

DEFINITIONS

1. probe_subsystem_event
2. probe_subsystem_eventb
3. probe_init
4. probe_fini

/* probe-example.c
 *
 * Connects two functions to marker call sites.
 *
 * (C) Copyright 2007 Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
 *
 * This file is released under the GPLv2.
 * See the file COPYING for more details.
 */

#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/marker.h>
#include <asm/atomic.h>

struct probe_data {
        const char *name;
        const char *format;
        marker_probe_func *probe_func;
};

void probe_subsystem_event(void *probe_data, void *call_data,
        const char *format, va_list *args)
{
        /* Declare args */
        unsigned int value;
        const char *mystr;

        /* Assign args */
        value = va_arg(*args, typeof(value));
        mystr = va_arg(*args, typeof(mystr));

        /* Call printk */
        printk(KERN_INFO "Value %u, string %s\n", value, mystr);

        /* or count, check rights, serialize data in a buffer */
}

atomic_t eventb_count = ATOMIC_INIT(0);

void probe_subsystem_eventb(void *probe_data, void *call_data,
        const char *format, va_list *args)
{
        /* Increment counter */
        atomic_inc(&eventb_count);
}

static struct probe_data probe_array[] =
{
        {       .name = "subsystem_event",
                .format = "integer %d string %s",
                .probe_func = probe_subsystem_event },
        {       .name = "subsystem_eventb",
                .format = MARK_NOARGS,
                .probe_func = probe_subsystem_eventb },
};

static int __init probe_init(void)
{
        int result;
        int i;

        for (i = 0; i < ARRAY_SIZE(probe_array); i++) {
                result = marker_probe_register(probe_array[i].name,
                                probe_array[i].format,
                                probe_array[i].probe_func, &probe_array[i]);
                if (result)
                        printk(KERN_INFO "Unable to register probe %s\n",
                                probe_array[i].name);
        }
        return 0;
}

static void __exit probe_fini(void)
{
        int i;

        for (i = 0; i < ARRAY_SIZE(probe_array); i++)
                marker_probe_unregister(probe_array[i].name,
                        probe_array[i].probe_func, &probe_array[i]);
        printk(KERN_INFO "Number of event b : %u\n",
                        atomic_read(&eventb_count));
}

module_init(probe_init);
module_exit(probe_fini);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Mathieu Desnoyers");
MODULE_DESCRIPTION("SUBSYSTEM Probe");