From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Thu, 16 Jun 2011 19:37:16 +0000 (-0400)
Subject: add ltt-probes.c
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=ce5aef0bb1fdfec2688f57aa2356447577ca64db;p=ust.git

add ltt-probes.c

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
---

diff --git a/libust/ltt-probes.c b/libust/ltt-probes.c
new file mode 100644
index 0000000..45d2dab
--- /dev/null
+++ b/libust/ltt-probes.c
@@ -0,0 +1,163 @@
+/*
+ * ltt-probes.c
+ *
+ * Copyright 2010 (c) - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * Holds LTTng probes registry.
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+#include <linux/module.h>
+#include <linux/list.h>
+#include <linux/mutex.h>
+#include <linux/seq_file.h>
+
+#include "ltt-events.h"
+
+static LIST_HEAD(probe_list);
+static DEFINE_MUTEX(probe_mutex);
+
+static
+const struct lttng_event_desc *find_event(const char *name)
+{
+	struct lttng_probe_desc *probe_desc;
+	int i;
+
+	list_for_each_entry(probe_desc, &probe_list, head) {
+		for (i = 0; i < probe_desc->nr_events; i++) {
+			if (!strcmp(probe_desc->event_desc[i].name, name))
+				return &probe_desc->event_desc[i];
+		}
+	}
+	return NULL;
+}
+
+int ltt_probe_register(struct lttng_probe_desc *desc)
+{
+	int ret = 0;
+	int i;
+
+	mutex_lock(&probe_mutex);
+	/*
+	 * TODO: This is O(N^2). Turn into a hash table when probe registration
+	 * overhead becomes an issue.
+	 */
+	for (i = 0; i < desc->nr_events; i++) {
+		if (find_event(desc->event_desc[i].name)) {
+			ret = -EEXIST;
+			goto end;
+		}
+	}
+	list_add(&desc->head, &probe_list);
+end:
+	mutex_unlock(&probe_mutex);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(ltt_probe_register);
+
+void ltt_probe_unregister(struct lttng_probe_desc *desc)
+{
+	mutex_lock(&probe_mutex);
+	list_del(&desc->head);
+	mutex_unlock(&probe_mutex);
+}
+EXPORT_SYMBOL_GPL(ltt_probe_unregister);
+
+const struct lttng_event_desc *ltt_event_get(const char *name)
+{
+	const struct lttng_event_desc *event;
+	int ret;
+
+	mutex_lock(&probe_mutex);
+	event = find_event(name);
+	mutex_unlock(&probe_mutex);
+	if (!event)
+		return NULL;
+	ret = try_module_get(event->owner);
+	WARN_ON_ONCE(!ret);
+	return event;
+}
+EXPORT_SYMBOL_GPL(ltt_event_get);
+
+void ltt_event_put(const struct lttng_event_desc *event)
+{
+	module_put(event->owner);
+}
+EXPORT_SYMBOL_GPL(ltt_event_put);
+
+static
+void *tp_list_start(struct seq_file *m, loff_t *pos)
+{
+	struct lttng_probe_desc *probe_desc;
+	int iter = 0, i;
+
+	mutex_lock(&probe_mutex);
+	list_for_each_entry(probe_desc, &probe_list, head) {
+		for (i = 0; i < probe_desc->nr_events; i++) {
+			if (iter++ >= *pos)
+				return (void *) &probe_desc->event_desc[i];
+		}
+	}
+	/* End of list */
+	return NULL;
+}
+
+static
+void *tp_list_next(struct seq_file *m, void *p, loff_t *ppos)
+{
+	struct lttng_probe_desc *probe_desc;
+	int iter = 0, i;
+
+	(*ppos)++;
+	list_for_each_entry(probe_desc, &probe_list, head) {
+		for (i = 0; i < probe_desc->nr_events; i++) {
+			if (iter++ >= *ppos)
+				return (void *) &probe_desc->event_desc[i];
+		}
+	}
+	/* End of list */
+	return NULL;
+}
+
+static
+void tp_list_stop(struct seq_file *m, void *p)
+{
+	mutex_unlock(&probe_mutex);
+}
+
+static
+int tp_list_show(struct seq_file *m, void *p)
+{
+	const struct lttng_event_desc *probe_desc = p;
+
+	/*
+	 * Don't export lttng internal events (metadata).
+	 */
+	if (!strncmp(probe_desc->name, "lttng_", sizeof("lttng_") - 1))
+		return 0;
+	seq_printf(m,	"event { name = %s; };\n",
+		   probe_desc->name);
+	return 0;
+}
+
+static
+const struct seq_operations lttng_tracepoint_list_seq_ops = {
+	.start = tp_list_start,
+	.next = tp_list_next,
+	.stop = tp_list_stop,
+	.show = tp_list_show,
+};
+
+static
+int lttng_tracepoint_list_open(struct inode *inode, struct file *file)
+{
+	return seq_open(file, &lttng_tracepoint_list_seq_ops);
+}
+
+const struct file_operations lttng_tracepoint_list_fops = {
+	.open = lttng_tracepoint_list_open,
+	.read = seq_read,
+	.llseek = seq_lseek,
+	.release = seq_release,
+};