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/*
* 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/seq_file.h>
#include <linux/debugfs.h>
#include "trace.h"
/* List of stat entries from a tracer */
struct trace_stat_list {
struct list_head list;
void *stat;
};
static LIST_HEAD(stat_list);
/*
* This is a copy of the current tracer to avoid racy
* and dangerous output while the current tracer is
* switched.
*/
static struct tracer current_tracer;
/*
* Protect both the current tracer and the global
* stat list.
*/
static DEFINE_MUTEX(stat_list_mutex);
static void reset_stat_list(void)
{
struct trace_stat_list *node, *next;
list_for_each_entry_safe(node, next, &stat_list, list)
kfree(node);
INIT_LIST_HEAD(&stat_list);
}
void init_tracer_stat(struct tracer *trace)
{
mutex_lock(&stat_list_mutex);
current_tracer = *trace;
mutex_unlock(&stat_list_mutex);
}
/*
* 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(void)
{
struct trace_stat_list *iter_entry, *new_entry;
void *prev_stat;
int ret = 0;
int i;
mutex_lock(&stat_list_mutex);
reset_stat_list();
if (!current_tracer.stat_start || !current_tracer.stat_next ||
!current_tracer.stat_show)
goto exit;
if (!current_tracer.stat_cmp)
current_tracer.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, &stat_list);
new_entry->stat = current_tracer.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 = current_tracer.stat_next(prev_stat, i);
/* End of insertion */
if (!new_entry->stat)
break;
list_for_each_entry(iter_entry, &stat_list, list) {
/* Insertion with a descendent sorting */
if (current_tracer.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,
&stat_list)) {
list_add(&new_entry->list, &iter_entry->list);
break;
}
}
prev_stat = new_entry->stat;
}
exit:
mutex_unlock(&stat_list_mutex);
return ret;
exit_free_list:
reset_stat_list();
mutex_unlock(&stat_list_mutex);
return ret;
}
static void *stat_seq_start(struct seq_file *s, loff_t *pos)
{
struct list_head *l = (struct list_head *)s->private;
/* Prevent from tracer switch or stat_list modification */
mutex_lock(&stat_list_mutex);
/* If we are in the beginning of the file, print the headers */
if (!*pos && current_tracer.stat_headers)
current_tracer.stat_headers(s);
return seq_list_start(l, *pos);
}
static void *stat_seq_next(struct seq_file *s, void *p, loff_t *pos)
{
struct list_head *l = (struct list_head *)s->private;
return seq_list_next(p, l, pos);
}
static void stat_seq_stop(struct seq_file *m, void *p)
{
mutex_unlock(&stat_list_mutex);
}
static int stat_seq_show(struct seq_file *s, void *v)
{
struct trace_stat_list *entry =
list_entry(v, struct trace_stat_list, list);
return current_tracer.stat_show(s, entry->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
};
static int tracing_stat_open(struct inode *inode, struct file *file)
{
int ret;
ret = seq_open(file, &trace_stat_seq_ops);
if (!ret) {
struct seq_file *m = file->private_data;
m->private = &stat_list;
ret = stat_seq_init();
}
return ret;
}
/*
* Avoid consuming memory with our now useless list.
*/
static int tracing_stat_release(struct inode *i, struct file *f)
{
mutex_lock(&stat_list_mutex);
reset_stat_list();
mutex_unlock(&stat_list_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 __init tracing_stat_init(void)
{
struct dentry *d_tracing;
struct dentry *entry;
d_tracing = tracing_init_dentry();
entry = debugfs_create_file("trace_stat", 0444, d_tracing,
NULL,
&tracing_stat_fops);
if (!entry)
pr_warning("Could not create debugfs "
"'trace_stat' entry\n");
return 0;
}
fs_initcall(tracing_stat_init);
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