tracing: Remove tracepoint sample code

The tracepoint sample code was used to teach developers how to
create their own tracepoints. But now the trace_events have been
added as a higher level that is used directly by developers today.

Only the trace_event code should use the tracepoint interface
directly and no new tracepoints should be added.

Besides, the example had a race condition with the use of the
->d_name.name dentry field, as pointed out by Al Viro.

Best just to remove the code so it wont be used by other developers.

Link: http://lkml.kernel.org/r/[e-mail]

Cc: Al Viro <[e-mail]>
Acked-by: Mathieu Desnoyers <[e-mail]>
Signed-off-by: Steven Rostedt <[e-mail]>

samples/Kconfig

···
 
 if SAMPLES
 
-config SAMPLE_TRACEPOINTS
-	tristate "Build tracepoints examples -- loadable modules only"
-	depends on TRACEPOINTS && m
-	help
-	  This build tracepoints example modules.
-
 config SAMPLE_TRACE_EVENTS
 	tristate "Build trace_events examples -- loadable modules only"
 	depends on EVENT_TRACING && m

samples/Makefile

···
 # Makefile for Linux samples code
 
-obj-$(CONFIG_SAMPLES)	+= kobject/ kprobes/ tracepoints/ trace_events/ \
+obj-$(CONFIG_SAMPLES)	+= kobject/ kprobes/ trace_events/ \
 			   hw_breakpoint/ kfifo/ kdb/ hidraw/ rpmsg/ seccomp/

samples/tracepoints/Makefile

···
-# 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

···
-#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>
-
-DECLARE_TRACE(subsys_event,
-	TP_PROTO(struct inode *inode, struct file *file),
-	TP_ARGS(inode, file));
-DECLARE_TRACE_NOARGS(subsys_eventb);
-#endif

samples/tracepoints/tracepoint-probe-sample.c

···
-/*
- * 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(void *ignore,
-			       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 *ignore)
-{
-	printk(KERN_INFO "Event B is encountered\n");
-}
-
-static int __init tp_sample_trace_init(void)
-{
-	int ret;
-
-	ret = register_trace_subsys_event(probe_subsys_event, NULL);
-	WARN_ON(ret);
-	ret = register_trace_subsys_eventb(probe_subsys_eventb, NULL);
-	WARN_ON(ret);
-
-	return 0;
-}
-
-module_init(tp_sample_trace_init);
-
-static void __exit tp_sample_trace_exit(void)
-{
-	unregister_trace_subsys_eventb(probe_subsys_eventb, NULL);
-	unregister_trace_subsys_event(probe_subsys_event, NULL);
-	tracepoint_synchronize_unregister();
-}
-
-module_exit(tp_sample_trace_exit);
-
-MODULE_LICENSE("GPL");
-MODULE_AUTHOR("Mathieu Desnoyers");
-MODULE_DESCRIPTION("Tracepoint Probes Samples");

samples/tracepoints/tracepoint-probe-sample2.c

···
-/*
- * tracepoint-probe-sample2.c
- *
- * 2nd sample tracepoint probes.
- */
-
-#include <linux/module.h>
-#include <linux/fs.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(void *ignore,
-			       struct inode *inode, struct file *file)
-{
-	printk(KERN_INFO "Event is encountered with inode number %lu\n",
-		inode->i_ino);
-}
-
-static int __init tp_sample_trace_init(void)
-{
-	int ret;
-
-	ret = register_trace_subsys_event(probe_subsys_event, NULL);
-	WARN_ON(ret);
-
-	return 0;
-}
-
-module_init(tp_sample_trace_init);
-
-static void __exit tp_sample_trace_exit(void)
-{
-	unregister_trace_subsys_event(probe_subsys_event, NULL);
-	tracepoint_synchronize_unregister();
-}
-
-module_exit(tp_sample_trace_exit);
-
-MODULE_LICENSE("GPL");
-MODULE_AUTHOR("Mathieu Desnoyers");
-MODULE_DESCRIPTION("Tracepoint Probes Samples");

samples/tracepoints/tracepoint-sample.c

···
-/* tracepoint-sample.c
- *
- * Executes a tracepoint when /proc/tracepoint-sample is opened.
- *
- * (C) Copyright 2007 Mathieu Desnoyers <[e-mail]>
- *
- * This file is released under the GPLv2.
- * See the file COPYING for more details.
- */
-
-#include <linux/module.h>
-#include <linux/sched.h>
-#include <linux/proc_fs.h>
-#include "tp-samples-trace.h"
-
-DEFINE_TRACE(subsys_event);
-DEFINE_TRACE(subsys_eventb);
-
-struct proc_dir_entry *pentry_sample;
-
-static int my_open(struct inode *inode, struct file *file)
-{
-	int i;
-
-	trace_subsys_event(inode, file);
-	for (i = 0; i < 10; i++)
-		trace_subsys_eventb();
-	return -EPERM;
-}
-
-static const struct file_operations mark_ops = {
-	.open = my_open,
-	.llseek = noop_llseek,
-};
-
-static int __init sample_init(void)
-{
-	printk(KERN_ALERT "sample init\n");
-	pentry_sample = proc_create("tracepoint-sample", 0444, NULL,
-		&mark_ops);
-	if (!pentry_sample)
-		return -EPERM;
-	return 0;
-}
-
-static void __exit sample_exit(void)
-{
-	printk(KERN_ALERT "sample exit\n");
-	remove_proc_entry("tracepoint-sample", NULL);
-}
-
-module_init(sample_init)
-module_exit(sample_exit)
-
-MODULE_LICENSE("GPL");
-MODULE_AUTHOR("Mathieu Desnoyers");
-MODULE_DESCRIPTION("Tracepoint sample");