v4.19.13 snapshot.
diff --git a/kernel/trace/trace_stat.c b/kernel/trace/trace_stat.c
new file mode 100644
index 0000000..75bf1bc
--- /dev/null
+++ b/kernel/trace/trace_stat.c
@@ -0,0 +1,359 @@
+// 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/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);
+}
+
+typedef int (*cmp_stat_t)(void *, void *);
+
+static int insert_stat(struct rb_root *root, void *stat, cmp_stat_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(void *p1, 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 = 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)
+{
+ struct dentry *d_tracing;
+
+ d_tracing = tracing_init_dentry();
+ if (IS_ERR(d_tracing))
+ return 0;
+
+ stat_dir = tracefs_create_dir("trace_stat", d_tracing);
+ if (!stat_dir)
+ pr_warn("Could not create tracefs 'trace_stat' entry\n");
+ return 0;
+}
+
+static int init_stat_file(struct stat_session *session)
+{
+ if (!stat_dir && tracing_stat_init())
+ return -ENODEV;
+
+ 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;
+
+ 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) {
+ mutex_unlock(&all_stat_sessions_mutex);
+ return -EINVAL;
+ }
+ }
+ mutex_unlock(&all_stat_sessions_mutex);
+
+ /* Init the session */
+ session = kzalloc(sizeof(*session), GFP_KERNEL);
+ if (!session)
+ return -ENOMEM;
+
+ session->ts = trace;
+ INIT_LIST_HEAD(&session->session_list);
+ mutex_init(&session->stat_mutex);
+
+ 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 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);
+}