/* * 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 *stat;	int ret = 0;	int i; 	mutex_lock(&session->stat_mutex);	reset_stat_session(session); 	if (!ts->stat_cmp)		ts->stat_cmp = dummy_cmp; 	stat = ts->stat_start();	if (!stat)		goto exit; 	/*	 * 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 = stat; 	/*	 * Iterate over the tracer stat entries and store them in a sorted	 * list.	 */	for (i = 1; ; i++) {		stat = ts->stat_next(stat, i); 		/* End of insertion */		if (!stat)			break; 		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 = stat; 		list_for_each_entry_reverse(iter_entry, &session->stat_list,				list) { 			/* Insertion with a descendent sorting */			if (ts->stat_cmp(iter_entry->stat,					new_entry->stat) >= 0) { 				list_add(&new_entry->list, &iter_entry->list);				break;			}		} 		/* The current larger value */		if (list_empty(&new_entry->list))			list_add(&new_entry->list, &session->stat_list);	}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)		return SEQ_START_TOKEN; 	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; 	if (p == SEQ_START_TOKEN)		return seq_list_start(&session->stat_list, *pos); 	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); 	if (v == SEQ_START_TOKEN)		return session->ts->stat_headers(s); 	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);}