// SPDX-License-Identifier: GPL-2.0
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/*
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* Infrastructure for statistic tracing (histogram output).
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*
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* Copyright (C) 2008-2009 Frederic Weisbecker <fweisbec@gmail.com>
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*
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* Based on the code from trace_branch.c which is
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* Copyright (C) 2008 Steven Rostedt <srostedt@redhat.com>
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*
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*/
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#include <linux/security.h>
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#include <linux/list.h>
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#include <linux/slab.h>
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#include <linux/rbtree.h>
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#include <linux/tracefs.h>
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#include "trace_stat.h"
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#include "trace.h"
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/*
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* List of stat red-black nodes from a tracer
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* We use a such tree to sort quickly the stat
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* entries from the tracer.
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*/
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struct stat_node {
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struct rb_node node;
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void *stat;
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};
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/* A stat session is the stats output in one file */
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struct stat_session {
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struct list_head session_list;
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struct tracer_stat *ts;
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struct rb_root stat_root;
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struct mutex stat_mutex;
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struct dentry *file;
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};
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/* All of the sessions currently in use. Each stat file embed one session */
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static LIST_HEAD(all_stat_sessions);
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static DEFINE_MUTEX(all_stat_sessions_mutex);
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/* The root directory for all stat files */
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static struct dentry *stat_dir;
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static void __reset_stat_session(struct stat_session *session)
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{
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struct stat_node *snode, *n;
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rbtree_postorder_for_each_entry_safe(snode, n, &session->stat_root, node) {
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if (session->ts->stat_release)
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session->ts->stat_release(snode->stat);
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kfree(snode);
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}
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session->stat_root = RB_ROOT;
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}
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static void reset_stat_session(struct stat_session *session)
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{
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mutex_lock(&session->stat_mutex);
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__reset_stat_session(session);
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mutex_unlock(&session->stat_mutex);
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}
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static void destroy_session(struct stat_session *session)
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{
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tracefs_remove(session->file);
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__reset_stat_session(session);
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mutex_destroy(&session->stat_mutex);
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kfree(session);
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}
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static int insert_stat(struct rb_root *root, void *stat, cmp_func_t cmp)
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{
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struct rb_node **new = &(root->rb_node), *parent = NULL;
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struct stat_node *data;
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data = kzalloc(sizeof(*data), GFP_KERNEL);
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if (!data)
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return -ENOMEM;
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data->stat = stat;
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/*
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* Figure out where to put new node
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* This is a descendent sorting
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*/
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while (*new) {
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struct stat_node *this;
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int result;
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this = container_of(*new, struct stat_node, node);
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result = cmp(data->stat, this->stat);
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parent = *new;
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if (result >= 0)
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new = &((*new)->rb_left);
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else
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new = &((*new)->rb_right);
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}
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rb_link_node(&data->node, parent, new);
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rb_insert_color(&data->node, root);
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return 0;
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}
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/*
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* For tracers that don't provide a stat_cmp callback.
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* This one will force an insertion as right-most node
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* in the rbtree.
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*/
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static int dummy_cmp(const void *p1, const void *p2)
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{
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return -1;
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}
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/*
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* Initialize the stat rbtree at each trace_stat file opening.
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* All of these copies and sorting are required on all opening
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* since the stats could have changed between two file sessions.
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*/
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static int stat_seq_init(struct stat_session *session)
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{
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struct tracer_stat *ts = session->ts;
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struct rb_root *root = &session->stat_root;
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void *stat;
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int ret = 0;
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int i;
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mutex_lock(&session->stat_mutex);
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__reset_stat_session(session);
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if (!ts->stat_cmp)
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ts->stat_cmp = dummy_cmp;
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stat = ts->stat_start(ts);
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if (!stat)
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goto exit;
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ret = insert_stat(root, stat, ts->stat_cmp);
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if (ret)
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goto exit;
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/*
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* Iterate over the tracer stat entries and store them in an rbtree.
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*/
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for (i = 1; ; i++) {
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stat = ts->stat_next(stat, i);
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/* End of insertion */
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if (!stat)
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break;
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ret = insert_stat(root, stat, ts->stat_cmp);
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if (ret)
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goto exit_free_rbtree;
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}
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exit:
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mutex_unlock(&session->stat_mutex);
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return ret;
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exit_free_rbtree:
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__reset_stat_session(session);
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mutex_unlock(&session->stat_mutex);
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return ret;
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}
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static void *stat_seq_start(struct seq_file *s, loff_t *pos)
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{
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struct stat_session *session = s->private;
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struct rb_node *node;
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int n = *pos;
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int i;
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/* Prevent from tracer switch or rbtree modification */
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mutex_lock(&session->stat_mutex);
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/* If we are in the beginning of the file, print the headers */
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if (session->ts->stat_headers) {
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if (n == 0)
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return SEQ_START_TOKEN;
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n--;
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}
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node = rb_first(&session->stat_root);
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for (i = 0; node && i < n; i++)
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node = rb_next(node);
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return node;
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}
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static void *stat_seq_next(struct seq_file *s, void *p, loff_t *pos)
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{
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struct stat_session *session = s->private;
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struct rb_node *node = p;
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(*pos)++;
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if (p == SEQ_START_TOKEN)
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return rb_first(&session->stat_root);
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return rb_next(node);
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}
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static void stat_seq_stop(struct seq_file *s, void *p)
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{
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struct stat_session *session = s->private;
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mutex_unlock(&session->stat_mutex);
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}
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static int stat_seq_show(struct seq_file *s, void *v)
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{
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struct stat_session *session = s->private;
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struct stat_node *l = container_of(v, struct stat_node, node);
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if (v == SEQ_START_TOKEN)
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return session->ts->stat_headers(s);
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return session->ts->stat_show(s, l->stat);
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}
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static const struct seq_operations trace_stat_seq_ops = {
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.start = stat_seq_start,
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.next = stat_seq_next,
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.stop = stat_seq_stop,
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.show = stat_seq_show
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};
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/* The session stat is refilled and resorted at each stat file opening */
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static int tracing_stat_open(struct inode *inode, struct file *file)
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{
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int ret;
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struct seq_file *m;
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struct stat_session *session = inode->i_private;
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ret = security_locked_down(LOCKDOWN_TRACEFS);
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if (ret)
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return ret;
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ret = stat_seq_init(session);
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if (ret)
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return ret;
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ret = seq_open(file, &trace_stat_seq_ops);
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if (ret) {
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reset_stat_session(session);
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return ret;
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}
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m = file->private_data;
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m->private = session;
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return ret;
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}
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/*
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* Avoid consuming memory with our now useless rbtree.
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*/
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static int tracing_stat_release(struct inode *i, struct file *f)
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{
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struct stat_session *session = i->i_private;
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reset_stat_session(session);
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return seq_release(i, f);
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}
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static const struct file_operations tracing_stat_fops = {
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.open = tracing_stat_open,
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.read = seq_read,
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.llseek = seq_lseek,
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.release = tracing_stat_release
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};
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static int tracing_stat_init(void)
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{
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int ret;
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ret = tracing_init_dentry();
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if (ret)
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return -ENODEV;
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stat_dir = tracefs_create_dir("trace_stat", NULL);
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if (!stat_dir) {
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pr_warn("Could not create tracefs 'trace_stat' entry\n");
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return -ENOMEM;
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}
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return 0;
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}
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static int init_stat_file(struct stat_session *session)
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{
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int ret;
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if (!stat_dir && (ret = tracing_stat_init()))
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return ret;
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session->file = tracefs_create_file(session->ts->name, 0644,
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stat_dir,
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session, &tracing_stat_fops);
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if (!session->file)
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return -ENOMEM;
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return 0;
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}
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int register_stat_tracer(struct tracer_stat *trace)
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{
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struct stat_session *session, *node;
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int ret = -EINVAL;
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if (!trace)
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return -EINVAL;
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if (!trace->stat_start || !trace->stat_next || !trace->stat_show)
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return -EINVAL;
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/* Already registered? */
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mutex_lock(&all_stat_sessions_mutex);
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list_for_each_entry(node, &all_stat_sessions, session_list) {
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if (node->ts == trace)
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goto out;
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}
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ret = -ENOMEM;
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/* Init the session */
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session = kzalloc(sizeof(*session), GFP_KERNEL);
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if (!session)
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goto out;
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session->ts = trace;
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INIT_LIST_HEAD(&session->session_list);
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mutex_init(&session->stat_mutex);
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ret = init_stat_file(session);
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if (ret) {
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destroy_session(session);
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goto out;
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}
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ret = 0;
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/* Register */
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list_add_tail(&session->session_list, &all_stat_sessions);
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out:
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mutex_unlock(&all_stat_sessions_mutex);
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return ret;
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}
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void unregister_stat_tracer(struct tracer_stat *trace)
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{
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struct stat_session *node, *tmp;
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mutex_lock(&all_stat_sessions_mutex);
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list_for_each_entry_safe(node, tmp, &all_stat_sessions, session_list) {
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if (node->ts == trace) {
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list_del(&node->session_list);
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destroy_session(node);
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break;
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}
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}
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mutex_unlock(&all_stat_sessions_mutex);
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}
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