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    Subject[patch 4/5] Linux Kernel Markers - Samples
    Module example showing how to use the Linux Kernel Markers.

    Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
    ---
    samples/Kconfig | 5 +
    samples/Makefile | 3 +
    samples/markers/Makefile | 4 +
    samples/markers/marker-example.c | 55 +++++++++++++++++++++
    samples/markers/probe-example.c | 98 +++++++++++++++++++++++++++++++++++++++
    5 files changed, 165 insertions(+)

    Index: linux-2.6-lttng/samples/markers/Makefile
    ===================================================================
    --- /dev/null 1970-01-01 00:00:00.000000000 +0000
    +++ linux-2.6-lttng/samples/markers/Makefile 2007-09-24 18:41:08.000000000 -0400
    @@ -0,0 +1,4 @@
    +# builds the kprobes example kernel modules;
    +# then to use one (as root): insmod <module_name.ko>
    +
    +obj-$(CONFIG_SAMPLE_MARKERS) += probe-example.o marker-example.o
    Index: linux-2.6-lttng/samples/markers/marker-example.c
    ===================================================================
    --- /dev/null 1970-01-01 00:00:00.000000000 +0000
    +++ linux-2.6-lttng/samples/markers/marker-example.c 2007-09-24 18:41:08.000000000 -0400
    @@ -0,0 +1,55 @@
    +/* marker-example.c
    + *
    + * Executes a marker when /proc/marker-example is opened.
    + *
    + * (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/module.h>
    +#include <linux/marker.h>
    +#include <linux/sched.h>
    +#include <linux/proc_fs.h>
    +
    +struct proc_dir_entry *pentry_example = NULL;
    +
    +static int my_open(struct inode *inode, struct file *file)
    +{
    + int i;
    +
    + trace_mark(subsystem_event, "%d %s", 123, "example string");
    + for (i=0; i<10; i++) {
    + trace_mark(subsystem_eventb, MARK_NOARGS);
    + }
    + return -EPERM;
    +}
    +
    +static struct file_operations mark_ops = {
    + .open = my_open,
    +};
    +
    +static int example_init(void)
    +{
    + printk(KERN_ALERT "example init\n");
    + pentry_example = create_proc_entry("marker-example", 0444, NULL);
    + if (pentry_example)
    + pentry_example->proc_fops = &mark_ops;
    + else
    + return -EPERM;
    + return 0;
    +}
    +
    +static void example_exit(void)
    +{
    + printk(KERN_ALERT "example exit\n");
    + remove_proc_entry("marker-example", NULL);
    +}
    +
    +module_init(example_init)
    +module_exit(example_exit)
    +
    +MODULE_LICENSE("GPL");
    +MODULE_AUTHOR("Mathieu Desnoyers");
    +MODULE_DESCRIPTION("Marker example");
    Index: linux-2.6-lttng/samples/markers/probe-example.c
    ===================================================================
    --- /dev/null 1970-01-01 00:00:00.000000000 +0000
    +++ linux-2.6-lttng/samples/markers/probe-example.c 2007-09-24 18:41:08.000000000 -0400
    @@ -0,0 +1,98 @@
    +/* 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(const struct __mark_marker *mdata,
    + void *private, const char *format, ...)
    +{
    + va_list ap;
    + /* Declare args */
    + unsigned int value;
    + const char *mystr;
    +
    + /* Assign args */
    + va_start(ap, format);
    + value = va_arg(ap, typeof(value));
    + mystr = va_arg(ap, typeof(mystr));
    +
    + /* Call printk */
    + printk("Value %u, string %s\n", value, mystr);
    +
    + /* or count, check rights, serialize data in a buffer */
    +
    + va_end(ap);
    +}
    +
    +atomic_t eventb_count = ATOMIC_INIT(0);
    +
    +void probe_subsystem_eventb(const struct __mark_marker *mdata,
    + void *private, const char *format, ...)
    +{
    + /* Increment counter */
    + atomic_inc(&eventb_count);
    +}
    +
    +static struct probe_data probe_array[] =
    +{
    + { .name = "subsystem_event",
    + .format = "%d %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);
    + result = marker_arm(probe_array[i].name);
    + if (result)
    + printk(KERN_INFO "Unable to arm 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);
    + }
    + printk("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");
    Index: linux-2.6-lttng/samples/Makefile
    ===================================================================
    --- /dev/null 1970-01-01 00:00:00.000000000 +0000
    +++ linux-2.6-lttng/samples/Makefile 2007-09-24 18:43:41.000000000 -0400
    @@ -0,0 +1,3 @@
    +# Makefile for Linux samples code
    +
    +obj-$(CONFIG_SAMPLES) += markers/
    Index: linux-2.6-lttng/samples/Kconfig
    ===================================================================
    --- linux-2.6-lttng.orig/samples/Kconfig 2007-09-24 18:20:40.000000000 -0400
    +++ linux-2.6-lttng/samples/Kconfig 2007-09-24 18:41:08.000000000 -0400
    @@ -7,5 +7,10 @@ menuconfig SAMPLES

    if SAMPLES

    +config SAMPLE_MARKERS
    + tristate "Build markers examples -- loadable modules only"
    + depends on MARKERS && m
    + help
    + This build markers example modules.

    endif # SAMPLES
    --
    Mathieu Desnoyers
    Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
    OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68
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