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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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