From: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Date: Wed, 22 Dec 2010 17:45:51 +0000 (-0500)
Subject: Add probe registry
X-Git-Tag: v2.0-pre1~184
X-Git-Url: http://git.lttng.org/?p=lttng-modules.git;a=commitdiff_plain;h=02119ee59d5c39dfc2d3f7d82b0921314f64a624

Add probe registry

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

diff --git a/Makefile b/Makefile
index 19acdbb6..ac00f9c4 100644
--- a/Makefile
+++ b/Makefile
@@ -10,7 +10,8 @@ obj-m += ltt-ring-buffer-client-discard.o
 obj-m += ltt-ring-buffer-client-overwrite.o
 
 obj-m += ltt-relay.o
-ltt-relay-objs :=  ltt-events.o ltt-event-header.o ltt-debugfs-abi.o
+ltt-relay-objs :=  ltt-events.o ltt-event-header.o ltt-debugfs-abi.o \
+			ltt-probes.o
 
 obj-m += probes/
 
diff --git a/ltt-events.c b/ltt-events.c
index b8dbec69..0e34f6f8 100644
--- a/ltt-events.c
+++ b/ltt-events.c
@@ -284,10 +284,15 @@ static int __init ltt_events_init(void)
 	event_cache = KMEM_CACHE(ltt_event, 0);
 	if (!event_cache)
 		return -ENOMEM;
-	ret = ltt_debugfs_abi_init();
+	ret = ltt_probes_init();
 	if (ret)
 		goto error;
+	ret = ltt_debugfs_abi_init();
+	if (ret)
+		goto error_abi;
 	return 0;
+error_abi:
+	ltt_probes_exit();
 error:
 	kmem_cache_destroy(event_cache);
 	return ret;
@@ -300,6 +305,7 @@ static void __exit ltt_events_exit(void)
 	struct ltt_session *session, *tmpsession;
 
 	ltt_debugfs_abi_exit();
+	ltt_probes_exit();
 	list_for_each_entry_safe(session, tmpsession, &sessions, list)
 		ltt_session_destroy(session);
 	kmem_cache_destroy(event_cache);
diff --git a/ltt-events.h b/ltt-events.h
index ab90bad3..b888dd2b 100644
--- a/ltt-events.h
+++ b/ltt-events.h
@@ -96,4 +96,11 @@ void ltt_transport_unregister(struct ltt_transport *transport);
 int ltt_debugfs_abi_init(void);
 void ltt_debugfs_abi_exit(void);
 
+int ltt_probe_register(const char *name, void *cb);
+void ltt_probe_unregister(const char *name);
+void *ltt_probe_get(const char *name);
+void ltt_probe_put(void *cb);
+int ltt_probes_init(void);
+void ltt_probes_exit(void);
+
 #endif /* _LTT_EVENTS_H */
diff --git a/ltt-probes.c b/ltt-probes.c
new file mode 100644
index 00000000..9870b9d8
--- /dev/null
+++ b/ltt-probes.c
@@ -0,0 +1,111 @@
+/*
+ * ltt-probes.c
+ *
+ * Copyright 2010 (c) - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * Holds LTTng probes registry.
+ */
+
+#include <linux/module.h>
+#include <linux/list.h>
+#include <linux/mutex.h>
+#include <linux/slab.h>
+
+struct ltt_probe {
+	const char *name;
+	void *cb;
+	struct list_head list;
+};
+
+static LIST_HEAD(probe_list);
+static DEFINE_MUTEX(probe_mutex);
+static struct kmem_cache *probe_cache;
+
+static void *find_probe(const char *name)
+{
+	struct ltt_probe *probe;
+
+	list_for_each_entry(probe, &probe_list, list) {
+		if (!strcmp(probe->name, name))
+			return probe->cb;
+	}
+	return NULL;
+}
+
+int ltt_probe_register(const char *name, void *cb)
+{
+	struct ltt_probe *probe;
+	int ret = 0;
+
+	if (!cb)
+		return -EPERM;
+
+	mutex_lock(&probe_mutex);
+	if (find_probe(name)) {
+		ret = -EEXIST;
+		goto end;
+	}
+	probe = kmem_cache_zalloc(probe_cache, GFP_KERNEL);
+	if (!probe) {
+		ret = -ENOMEM;
+		goto end;
+	}
+	probe->name = name;
+	probe->cb = cb;
+	list_add(&probe->list, &probe_list);
+end:
+	mutex_unlock(&probe_mutex);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(ltt_probe_register);
+
+void ltt_probe_unregister(const char *name)
+{
+	struct ltt_probe *probe;
+
+	mutex_lock(&probe_mutex);
+	probe = find_probe(name);
+	WARN_ON_ONCE(!probe);
+	list_del(&probe->list);
+	mutex_unlock(&probe_mutex);
+	kmem_cache_free(probe_cache, probe);
+}
+EXPORT_SYMBOL_GPL(ltt_probe_unregister);
+
+void *ltt_probe_get(const char *name)
+{
+	struct ltt_probe *probe;
+	void *cb = NULL;
+	int ret;
+
+	mutex_lock(&probe_mutex);
+	probe = find_probe(name);
+	if (!probe)
+		goto end;
+	cb = probe->cb;
+	ret = try_module_get(__module_text_address((unsigned long) cb));
+	WARN_ON_ONCE(!ret);
+end:
+	mutex_unlock(&probe_mutex);
+	return cb;
+}
+EXPORT_SYMBOL_GPL(ltt_probe_get);
+
+void ltt_probe_put(void *cb)
+{
+	module_put(__module_text_address((unsigned long) cb));
+}
+EXPORT_SYMBOL_GPL(ltt_probe_put);
+
+int __init ltt_probes_init(void)
+{
+	probe_cache = KMEM_CACHE(ltt_probe, 0);
+	if (!probe_cache)
+		return -ENOMEM;
+	return 0;
+}
+
+void __exit ltt_probes_exit(void)
+{
+	kmem_cache_destroy(probe_cache);
+}