/*
* Infrastructure for statistic tracing (histogram output).
*
* Copyright (C) 2008 Frederic Weisbecker <fweisbec@gmail.com>
*
* Based on the code from trace_branch.c which is
* Copyright (C) 2008 Steven Rostedt <srostedt@redhat.com>
*
*/
#include <linux/list.h>
#include <linux/debugfs.h>
#include "trace_stat.h"
#include "trace.h"
/* List of stat entries from a tracer */
struct trace_stat_list {
struct list_head list;
void *stat;
};
/* A stat session is the stats output in one file */
struct tracer_stat_session {
struct list_head session_list;
struct tracer_stat *ts;
struct list_head stat_list;
struct mutex stat_mutex;
struct dentry *file;
};
/* All of the sessions currently in use. Each stat file embed one session */
static LIST_HEAD(all_stat_sessions);
static DEFINE_MUTEX(all_stat_sessions_mutex);
/* The root directory for all stat files */
static struct dentry *stat_dir;
static void reset_stat_session(struct tracer_stat_session *session)
{
struct trace_stat_list *node, *next;
list_for_each_entry_safe(node, next, &session->stat_list, list)
kfree(node);
INIT_LIST_HEAD(&session->stat_list);
}
static void destroy_session(struct tracer_stat_session *session)
{
debugfs_remove(session->file);
reset_stat_session(session);
mutex_destroy(&session->stat_mutex);
kfree(session);
}
/*
* For tracers that don't provide a stat_cmp callback.
* This one will force an immediate insertion on tail of
* the list.
*/
static int dummy_cmp(void *p1, void *p2)
{
return 1;
}
/*
* Initialize the stat list at each trace_stat file opening.
* All of these copies and sorting are required on all opening
* since the stats could have changed between two file sessions.
*/
static int stat_seq_init(struct tracer_stat_session *session)
{
struct trace_stat_list *iter_entry, *new_entry;
struct tracer_stat *ts = session->ts;
void *prev_stat;
int ret = 0;
int i;
mutex_lock(&session->stat_mutex);
reset_stat_session(session);
if (!ts->stat_cmp)
ts->stat_cmp = dummy_cmp;
/*
* The first entry. Actually this is the second, but the first
* one (the stat_list head) is pointless.
*/
new_entry = kmalloc(sizeof(struct trace_stat_list), GFP_KERNEL);
if (!new_entry) {
ret = -ENOMEM;
goto exit;
}
INIT_LIST_HEAD(&new_entry->list);
list_add(&new_entry->list, &session->stat_list);
new_entry->stat = ts->stat_start();
prev_stat = new_entry->stat;
/*
* Iterate over the tracer stat entries and store them in a sorted
* list.
*/
for (i = 1; ; i++) {
new_entry = kmalloc(sizeof(struct trace_stat_list), GFP_KERNEL);
if (!new_entry) {
ret = -ENOMEM;
goto exit_free_list;
}
INIT_LIST_HEAD(&new_entry->list);
new_entry->stat = ts->stat_next(prev_stat, i);
/* End of insertion */
if (!new_entry->stat)
break;
list_for_each_entry(iter_entry, &session->stat_list, list) {
/* Insertion with a descendent sorting */
if (ts->stat_cmp(new_entry->stat,
iter_entry->stat) > 0) {
list_add_tail(&new_entry->list,
&iter_entry->list);
break;
/* The current smaller value */
} else if (list_is_last(&iter_entry->list,
&session->stat_list)) {
list_add(&new_entry->list, &iter_entry->list);
break;
}
}
prev_stat = new_entry->stat;
}
exit:
mutex_unlock(&session->stat_mutex);
return ret;
exit_free_list:
reset_stat_session(session);
mutex_unlock(&session->stat_mutex);
return ret;
}
static void *stat_seq_start(struct seq_file *s, loff_t *pos)
{
struct tracer_stat_session *session = s->private;
/* Prevent from tracer switch or stat_list modification */
mutex_lock(&session->stat_mutex);
/* If we are in the beginning of the file, print the headers */
if (!*pos && session->ts->stat_headers)
session->ts->stat_headers(s);
return seq_list_start(&session->stat_list, *pos);
}
static void *stat_seq_next(struct seq_file *s, void *p, loff_t *pos)
{
struct tracer_stat_session *session = s->private;
return seq_list_next(p, &session->stat_list, pos);
}
static void stat_seq_stop(struct seq_file *s, void *p)
{
struct tracer_stat_session *session = s->private;
mutex_unlock(&session->stat_mutex);
}
static int stat_seq_show(struct seq_file *s, void *v)
{
struct tracer_stat_session *session = s->private;
struct trace_stat_list *l = list_entry(v, struct trace_stat_list, list);
return session->ts->stat_show(s, l->stat);
}
static const struct seq_operations trace_stat_seq_ops = {
.start = stat_seq_start,
.next = stat_seq_next,
.stop = stat_seq_stop,
.show = stat_seq_show
};
/* The session stat is refilled and resorted at each stat file opening */
static int tracing_stat_open(struct inode *inode, struct file *file)
{
int ret;
struct tracer_stat_session *session = inode->i_private;
ret = seq_open(file, &trace_stat_seq_ops);
if (!ret) {
struct seq_file *m = file->private_data;
m->private = session;
ret = stat_seq_init(session);
}
return ret;
}
/*
* Avoid consuming memory with our now useless list.
*/
static int tracing_stat_release(struct inode *i, struct file *f)
{
struct tracer_stat_session *session = i->i_private;
mutex_lock(&session->stat_mutex);
reset_stat_session(session);
mutex_unlock(&session->stat_mutex);
return 0;
}
static const struct file_operations tracing_stat_fops = {
.open = tracing_stat_open,
.read = seq_read,
.llseek = seq_lseek,
.release = tracing_stat_release
};
static int tracing_stat_init(void)
{
struct dentry *d_tracing;
d_tracing = tracing_init_dentry();
stat_dir = debugfs_create_dir("trace_stat", d_tracing);
if (!stat_dir)
pr_warning("Could not create debugfs "
"'trace_stat' entry\n");
return 0;
}
static int init_stat_file(struct tracer_stat_session *session)
{
if (!stat_dir && tracing_stat_init())
return -ENODEV;
session->file = debugfs_create_file(session->ts->name, 0644,
stat_dir,
session, &tracing_stat_fops);
if (!session->file)
return -ENOMEM;
return 0;
}
int register_stat_tracer(struct tracer_stat *trace)
{
struct tracer_stat_session *session, *node, *tmp;
int ret;
if (!trace)
return -EINVAL;
if (!trace->stat_start || !trace->stat_next || !trace->stat_show)
return -EINVAL;
/* Already registered? */
mutex_lock(&all_stat_sessions_mutex);
list_for_each_entry_safe(node, tmp, &all_stat_sessions, session_list) {
if (node->ts == trace) {
mutex_unlock(&all_stat_sessions_mutex);
return -EINVAL;
}
}
mutex_unlock(&all_stat_sessions_mutex);
/* Init the session */
session = kmalloc(sizeof(struct tracer_stat_session), GFP_KERNEL);
if (!session)
return -ENOMEM;
session->ts = trace;
INIT_LIST_HEAD(&session->session_list);
INIT_LIST_HEAD(&session->stat_list);
mutex_init(&session->stat_mutex);
session->file = NULL;
ret = init_stat_file(session);
if (ret) {
destroy_session(session);
return ret;
}
/* Register */
mutex_lock(&all_stat_sessions_mutex);
list_add_tail(&session->session_list, &all_stat_sessions);
mutex_unlock(&all_stat_sessions_mutex);
return 0;
}
void unregister_stat_tracer(struct tracer_stat *trace)
{
struct tracer_stat_session *node, *tmp;
mutex_lock(&all_stat_sessions_mutex);
list_for_each_entry_safe(node, tmp, &all_stat_sessions, session_list) {
if (node->ts == trace) {
list_del(&node->session_list);
destroy_session(node);
break;
}
}
mutex_unlock(&all_stat_sessions_mutex);
}
