FreeBSD/Linux Kernel Cross Reference
sys/samples/markers/probe-example.c

     /* 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));
            marker_synchronize_unregister();
    }
    
    module_init(probe_init);
    module_exit(probe_fini);
    
    MODULE_LICENSE("GPL");
    MODULE_AUTHOR("Mathieu Desnoyers");
    MODULE_DESCRIPTION("SUBSYSTEM Probe");

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