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Commit 4a089752 authored by Mathieu Desnoyers's avatar Mathieu Desnoyers Committed by Ingo Molnar
Browse files

tracing: tracepoints, samples 



Tracepoint example code under samples/.

Signed-off-by: default avatarMathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Acked-by: default avatar'Peter Zijlstra' <peterz@infradead.org>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 24b8d831

samples/Kconfig

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@@ -13,6 +13,12 @@ config SAMPLE_MARKERS 
	help

	  This build markers example modules.



config SAMPLE_TRACEPOINTS

	tristate "Build tracepoints examples -- loadable modules only"

	depends on TRACEPOINTS && m

	help

	  This build tracepoints example modules.



config SAMPLE_KOBJECT

	tristate "Build kobject examples"

	help

samples/Makefile

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# Makefile for Linux samples code



obj-$(CONFIG_SAMPLES)	+= markers/ kobject/ kprobes/
 
obj-$(CONFIG_SAMPLES)	+= markers/ kobject/ kprobes/ tracepoints/

samples/tracepoints/Makefile

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# builds the tracepoint example kernel modules;

# then to use one (as root):  insmod <module_name.ko>



obj-$(CONFIG_SAMPLE_TRACEPOINTS) += tracepoint-sample.o

obj-$(CONFIG_SAMPLE_TRACEPOINTS) += tracepoint-probe-sample.o

obj-$(CONFIG_SAMPLE_TRACEPOINTS) += tracepoint-probe-sample2.o

samples/tracepoints/tp-samples-trace.h

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#ifndef _TP_SAMPLES_TRACE_H

#define _TP_SAMPLES_TRACE_H



#include <linux/proc_fs.h>	/* for struct inode and struct file */

#include <linux/tracepoint.h>



DEFINE_TRACE(subsys_event,

	TPPROTO(struct inode *inode, struct file *file),

	TPARGS(inode, file));

DEFINE_TRACE(subsys_eventb,

	TPPROTO(void),

	TPARGS());

#endif

samples/tracepoints/tracepoint-probe-sample.c

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/*

 * tracepoint-probe-sample.c

 *

 * sample tracepoint probes.

 */



#include <linux/module.h>

#include <linux/file.h>

#include <linux/dcache.h>

#include "tp-samples-trace.h"



/*

 * Here the caller only guarantees locking for struct file and struct inode.

 * Locking must therefore be done in the probe to use the dentry.

 */

static void probe_subsys_event(struct inode *inode, struct file *file)

{

	path_get(&file->f_path);

	dget(file->f_path.dentry);

	printk(KERN_INFO "Event is encountered with filename %s\n",

		file->f_path.dentry->d_name.name);

	dput(file->f_path.dentry);

	path_put(&file->f_path);

}



static void probe_subsys_eventb(void)

{

	printk(KERN_INFO "Event B is encountered\n");

}



int __init tp_sample_trace_init(void)

{

	int ret;



	ret = register_trace_subsys_event(probe_subsys_event);

	WARN_ON(ret);

	ret = register_trace_subsys_eventb(probe_subsys_eventb);

	WARN_ON(ret);



	return 0;

}



module_init(tp_sample_trace_init);



void __exit tp_sample_trace_exit(void)

{

	unregister_trace_subsys_eventb(probe_subsys_eventb);

	unregister_trace_subsys_event(probe_subsys_event);

}



module_exit(tp_sample_trace_exit);



MODULE_LICENSE("GPL");

MODULE_AUTHOR("Mathieu Desnoyers");

MODULE_DESCRIPTION("Tracepoint Probes Samples");