// SPDX-License-Identifier: GPL-2.0/* * Infrastructure for statistic tracing (histogram output). * * Copyright (C) 2008-2009 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/security.h>#include <linux/list.h>#include <linux/slab.h>#include <linux/rbtree.h>#include <linux/tracefs.h>#include "trace_stat.h"#include "trace.h"  /* * List of stat red-black nodes from a tracer * We use a such tree to sort quickly the stat * entries from the tracer. */struct stat_node {	struct rb_node		node;	void			*stat;}; /* A stat session is the stats output in one file */struct stat_session {	struct list_head	session_list;	struct tracer_stat	*ts;	struct rb_root		stat_root;	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 stat_session *session){	struct stat_node *snode, *n; 	rbtree_postorder_for_each_entry_safe(snode, n, &session->stat_root, node) {		if (session->ts->stat_release)			session->ts->stat_release(snode->stat);		kfree(snode);	} 	session->stat_root = RB_ROOT;} static void reset_stat_session(struct stat_session *session){	mutex_lock(&session->stat_mutex);	__reset_stat_session(session);	mutex_unlock(&session->stat_mutex);} static void destroy_session(struct stat_session *session){	tracefs_remove(session->file);	__reset_stat_session(session);	mutex_destroy(&session->stat_mutex);	kfree(session);} static int insert_stat(struct rb_root *root, void *stat, cmp_func_t cmp){	struct rb_node **new = &(root->rb_node), *parent = NULL;	struct stat_node *data; 	data = kzalloc(sizeof(*data), GFP_KERNEL);	if (!data)		return -ENOMEM;	data->stat = stat; 	/*	 * Figure out where to put new node	 * This is a descendent sorting	 */	while (*new) {		struct stat_node *this;		int result; 		this = container_of(*new, struct stat_node, node);		result = cmp(data->stat, this->stat); 		parent = *new;		if (result >= 0)			new = &((*new)->rb_left);		else			new = &((*new)->rb_right);	} 	rb_link_node(&data->node, parent, new);	rb_insert_color(&data->node, root);	return 0;} /* * For tracers that don't provide a stat_cmp callback. * This one will force an insertion as right-most node * in the rbtree. */static int dummy_cmp(const void *p1, const void *p2){	return -1;} /* * Initialize the stat rbtree 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 stat_session *session){	struct tracer_stat *ts = session->ts;	struct rb_root *root = &session->stat_root;	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(ts);	if (!stat)		goto exit; 	ret = insert_stat(root, stat, ts->stat_cmp);	if (ret)		goto exit; 	/*	 * Iterate over the tracer stat entries and store them in an rbtree.	 */	for (i = 1; ; i++) {		stat = ts->stat_next(stat, i); 		/* End of insertion */		if (!stat)			break; 		ret = insert_stat(root, stat, ts->stat_cmp);		if (ret)			goto exit_free_rbtree;	} exit:	mutex_unlock(&session->stat_mutex);	return ret; exit_free_rbtree:	__reset_stat_session(session);	mutex_unlock(&session->stat_mutex);	return ret;}  static void *stat_seq_start(struct seq_file *s, loff_t *pos){	struct stat_session *session = s->private;	struct rb_node *node;	int n = *pos;	int i; 	/* Prevent from tracer switch or rbtree modification */	mutex_lock(&session->stat_mutex); 	/* If we are in the beginning of the file, print the headers */	if (session->ts->stat_headers) {		if (n == 0)			return SEQ_START_TOKEN;		n--;	} 	node = rb_first(&session->stat_root);	for (i = 0; node && i < n; i++)		node = rb_next(node); 	return node;} static void *stat_seq_next(struct seq_file *s, void *p, loff_t *pos){	struct stat_session *session = s->private;	struct rb_node *node = p; 	(*pos)++; 	if (p == SEQ_START_TOKEN)		return rb_first(&session->stat_root); 	return rb_next(node);} static void stat_seq_stop(struct seq_file *s, void *p){	struct stat_session *session = s->private;	mutex_unlock(&session->stat_mutex);} static int stat_seq_show(struct seq_file *s, void *v){	struct stat_session *session = s->private;	struct stat_node *l = container_of(v, struct stat_node, node); 	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 seq_file *m;	struct stat_session *session = inode->i_private; 	ret = security_locked_down(LOCKDOWN_TRACEFS);	if (ret)		return ret; 	ret = stat_seq_init(session);	if (ret)		return ret; 	ret = seq_open(file, &trace_stat_seq_ops);	if (ret) {		reset_stat_session(session);		return ret;	} 	m = file->private_data;	m->private = session;	return ret;} /* * Avoid consuming memory with our now useless rbtree. */static int tracing_stat_release(struct inode *i, struct file *f){	struct stat_session *session = i->i_private; 	reset_stat_session(session); 	return seq_release(i, f);} 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){	int ret; 	ret = tracing_init_dentry();	if (ret)		return -ENODEV; 	stat_dir = tracefs_create_dir("trace_stat", NULL);	if (!stat_dir) {		pr_warn("Could not create tracefs 'trace_stat' entry\n");		return -ENOMEM;	}	return 0;} static int init_stat_file(struct stat_session *session){	int ret; 	if (!stat_dir && (ret = tracing_stat_init()))		return ret; 	session->file = tracefs_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 stat_session *session, *node;	int ret = -EINVAL; 	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(node, &all_stat_sessions, session_list) {		if (node->ts == trace)			goto out;	} 	ret = -ENOMEM;	/* Init the session */	session = kzalloc(sizeof(*session), GFP_KERNEL);	if (!session)		goto out; 	session->ts = trace;	INIT_LIST_HEAD(&session->session_list);	mutex_init(&session->stat_mutex); 	ret = init_stat_file(session);	if (ret) {		destroy_session(session);		goto out;	} 	ret = 0;	/* Register */	list_add_tail(&session->session_list, &all_stat_sessions); out:	mutex_unlock(&all_stat_sessions_mutex); 	return ret;} void unregister_stat_tracer(struct tracer_stat *trace){	struct 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);}