1 files changed, 319 insertions, 0 deletions
diff --git a/kernel/trace/trace_stat.c b/kernel/trace/trace_stat.c
new file mode 100644
index 000000000000..39310e3434ee
--- /dev/null
+++ b/kernel/trace/trace_stat.c
@@ -0,0 +1,319 @@
+/*
+ * 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 *prev_stat;
+	int ret = 0;
+	int i;
+
+	mutex_lock(&session->stat_mutex);
+	reset_stat_session(session);
+
+	if (!ts->stat_cmp)
+		ts->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, &session->stat_list);
+
+	new_entry->stat = ts->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 = ts->stat_next(prev_stat, i);
+
+		/* End of insertion */
+		if (!new_entry->stat)
+			break;
+
+		list_for_each_entry(iter_entry, &session->stat_list, list) {
+
+			/* Insertion with a descendent sorting */
+			if (ts->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,
+						&session->stat_list)) {
+				list_add(&new_entry->list, &iter_entry->list);
+				break;
+			}
+		}
+
+		prev_stat = new_entry->stat;
+	}
+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)
+		session->ts->stat_headers(s);
+
+	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;
+
+	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);
+
+	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);
+}