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Commit 1473e441 authored by Steven Rostedt's avatar Steven Rostedt
Browse files

tracing: make event directory structure 



This patch adds the directory /debug/tracing/events/ that will contain
all the registered trace points.

 # ls /debug/tracing/events/
sched_kthread_stop      sched_process_fork  sched_switch
sched_kthread_stop_ret  sched_process_free  sched_wait_task
sched_migrate_task      sched_process_wait  sched_wakeup
sched_process_exit      sched_signal_send   sched_wakeup_new

 # ls /debug/tracing/events/sched_switch/
enable

 # cat /debug/tracing/events/sched_switch/enable
1

 # cat /debug/tracing/set_event
sched_switch

Signed-off-by: default avatarSteven Rostedt <srostedt@redhat.com>
parent f3fe8e4a

kernel/trace/trace_events.c

+132 −5
Original line number Diff line number Diff line
@@ -12,6 +12,11 @@ 


#include "trace_events.h"



#define events_for_each(event)						\

	for (event = __start_ftrace_events;				\

	     (unsigned long)event < (unsigned long)__stop_ftrace_events; \

	     event++)



void event_trace_printk(unsigned long ip, const char *fmt, ...)

{

	va_list ap;
@@ -39,15 +44,16 @@ static void ftrace_clear_events(void) 


static int ftrace_set_clr_event(char *buf, int set)

{

	struct ftrace_event_call *call = (void *)__start_ftrace_events;

	struct ftrace_event_call *call = __start_ftrace_events;





	while ((unsigned long)call < (unsigned long)__stop_ftrace_events) {

	events_for_each(call) {



		if (strcmp(buf, call->name) != 0) {

			call++;

		if (!call->name)

			continue;



		if (strcmp(buf, call->name) != 0)

			continue;

		}



		if (set) {

			/* Already set? */
@@ -223,6 +229,67 @@ ftrace_event_seq_open(struct inode *inode, struct file *file) 
	return ret;

}



static ssize_t

event_enable_read(struct file *filp, char __user *ubuf, size_t cnt,

		  loff_t *ppos)

{

	struct ftrace_event_call *call = filp->private_data;

	char *buf;



	if (call->enabled)

		buf = "1\n";

	else

		buf = "0\n";



	return simple_read_from_buffer(ubuf, cnt, ppos, buf, 2);

}



static ssize_t

event_enable_write(struct file *filp, const char __user *ubuf, size_t cnt,

		   loff_t *ppos)

{

	struct ftrace_event_call *call = filp->private_data;

	char buf[64];

	unsigned long val;

	int ret;



	if (cnt >= sizeof(buf))

		return -EINVAL;



	if (copy_from_user(&buf, ubuf, cnt))

		return -EFAULT;



	buf[cnt] = 0;



	ret = strict_strtoul(buf, 10, &val);

	if (ret < 0)

		return ret;



	switch (val) {

	case 0:

		if (!call->enabled)

			break;



		call->enabled = 0;

		call->unregfunc();

		break;

	case 1:

		if (call->enabled)

			break;



		call->enabled = 1;

		call->regfunc();

		break;



	default:

		return -EINVAL;

	}



	*ppos += cnt;



	return cnt;

}



static const struct seq_operations show_event_seq_ops = {

	.start = t_start,

	.next = t_next,
@@ -252,10 +319,59 @@ static const struct file_operations ftrace_set_event_fops = { 
	.release = seq_release,

};



static const struct file_operations ftrace_enable_fops = {

	.open = tracing_open_generic,

	.read = event_enable_read,

	.write = event_enable_write,

};



static struct dentry *event_trace_events_dir(void)

{

	static struct dentry *d_tracer;

	static struct dentry *d_events;



	if (d_events)

		return d_events;



	d_tracer = tracing_init_dentry();

	if (!d_tracer)

		return NULL;



	d_events = debugfs_create_dir("events", d_tracer);

	if (!d_events)

		pr_warning("Could not create debugfs "

			   "'events' directory\n");



	return d_events;

}



static int

event_create_dir(struct ftrace_event_call *call, struct dentry *d_events)

{

	struct dentry *entry;



	call->dir = debugfs_create_dir(call->name, d_events);

	if (!call->dir) {

		pr_warning("Could not create debugfs "

			   "'%s' directory\n", call->name);

		return -1;

	}



	entry = debugfs_create_file("enable", 0644, call->dir, call,

				    &ftrace_enable_fops);

	if (!entry)

		pr_warning("Could not create debugfs "

			   "'%s/enable' entry\n", call->name);



	return 0;

}



static __init int event_trace_init(void)

{

	struct ftrace_event_call *call = __start_ftrace_events;

	struct dentry *d_tracer;

	struct dentry *entry;

	struct dentry *d_events;



	d_tracer = tracing_init_dentry();

	if (!d_tracer)
@@ -275,6 +391,17 @@ static __init int event_trace_init(void) 
		pr_warning("Could not create debugfs "

			   "'set_event' entry\n");



	d_events = event_trace_events_dir();

	if (!d_events)

		return 0;



	events_for_each(call) {

		/* The linker may leave blanks */

		if (!call->name)

			continue;

		event_create_dir(call, d_events);

	}



	return 0;

}

fs_initcall(event_trace_init);

kernel/trace/trace_events.h

+5 −2
Original line number Diff line number Diff line 
#ifndef _LINUX_KERNEL_TRACE_EVENTS_H

#define _LINUX_KERNEL_TRACE_EVENTS_H



#include <linux/debugfs.h>

#include <linux/ftrace.h>

#include "trace.h"



struct ftrace_event_call {

	char		*name;

	struct dentry	*dir;

	int		enabled;

	int		(*regfunc)(void);

	void		(*unregfunc)(void);
@@ -39,6 +41,7 @@ static void ftrace_unreg_event_##call(void) \ 
}									\

									\

static struct ftrace_event_call __used					\

__attribute__((__aligned__(4)))						\

__attribute__((section("_ftrace_events"))) event_##call = {		\

	.name 			= #call,				\

	.regfunc		= ftrace_reg_event_##call,		\
@@ -46,7 +49,7 @@ __attribute__((section("_ftrace_events"))) event_##call = { \ 
}



void event_trace_printk(unsigned long ip, const char *fmt, ...);

extern unsigned long __start_ftrace_events[];

extern unsigned long __stop_ftrace_events[];

extern struct ftrace_event_call __start_ftrace_events[];

extern struct ftrace_event_call __stop_ftrace_events[];



#endif /* _LINUX_KERNEL_TRACE_EVENTS_H */