X-Git-Url: https://git.lttng.org/?a=blobdiff_plain;f=ltt-events.c;h=d6cb397e6a61d44a83c1e8eaa898e8f18976107f;hb=c0e31d2eb7b6d446c87cab8b18a8b8257b4ba3e8;hp=3060c07e05d2386d8d90d0482b3040d3d0f970b9;hpb=d4e1a740a3db547f3f9eaebae9200042fb89f7d6;p=lttng-modules.git

diff --git a/ltt-events.c b/ltt-events.c
index 3060c07e..d6cb397e 100644
--- a/ltt-events.c
+++ b/ltt-events.c
@@ -7,9 +7,13 @@
  */
 
 #include <linux/module.h>
+#include <linux/list.h>
+#include <linux/mutex.h>
+#include <linux/sched.h>
 #include "ltt-events.h"
 
 static LIST_HEAD(sessions);
+static LIST_HEAD(ltt_transport_list);
 static DEFINE_MUTEX(sessions_mutex);
 static struct kmem_cache *event_cache;
 
@@ -56,6 +60,38 @@ int ltt_session_destroy(struct ltt_session *session)
 	kfree(session);
 }
 
+int ltt_session_start(struct ltt_session *session)
+{
+	int ret = 0;
+
+	mutex_lock(&sessions_mutex);
+	if (session->active) {
+		ret = -EBUSY;
+		goto end;
+	}
+	session->active = 1;
+	synchronize_trace();	/* Wait for in-flight events to complete */
+end:
+	mutex_unlock(&sessions_mutex);
+	return ret
+}
+
+int ltt_session_stop(struct ltt_session *session)
+{
+	int ret = 0;
+
+	mutex_lock(&sessions_mutex);
+	if (!session->active) {
+		ret = -EBUSY;
+		goto end;
+	}
+	session->active = 0;
+	synchronize_trace();	/* Wait for in-flight events to complete */
+end:
+	mutex_unlock(&sessions_mutex);
+	return ret
+}
+
 struct ltt_channel *ltt_channel_create(struct ltt_session *session,
 				       int overwrite, void *buf_addr,
 				       size_t subbuf_size, size_t num_subbuf,
@@ -63,22 +99,35 @@ struct ltt_channel *ltt_channel_create(struct ltt_session *session,
 				       unsigned int read_timer_interval)
 {
 	struct ltt_channel *chan;
+	struct ltt_transport *transport = NULL, *tran_iter;
+	char *transport_name;
 
 	mutex_lock(&sessions_mutex);
 	if (session->active)
 		goto active;	/* Refuse to add channel to active session */
+	transport_name = overwrite ? "relay-overwrite" : "relay-discard";
+	list_for_each_entry(tran_iter, &ltt_transport_list, node) {
+		if (!strcmp(tran_iter->name, transport_name)) {
+			transport = tran_iter;
+			break;
+		}
+	}
+	if (!transport)
+		goto notransport;
 	chan = kmalloc(sizeof(struct ltt_channel), GFP_KERNEL);
 	if (!chan)
-		return NULL;
+		goto nomem;
 	chan->session = session;
 	init_waitqueue_head(&chan->notify_wait);
-
-	/* TODO: create rb channel */
+	transport->ops.channel_create(session, buf_addr, subbuf_size,
+				      num_subbuf, switch_timer_interval,
+				      read_timer_interval);
 	list_add(&chan->list, &session->chan);
 	mutex_unlock(&sessions_mutex);
 	return chan;
 
-exist:
+nomem:
+notransport:
 active:
 	mutex_unlock(&sessions_mutex);
 	return NULL;
@@ -89,7 +138,7 @@ active:
  */
 int _ltt_channel_destroy(struct ltt_channel *chan)
 {
-	/* TODO: destroy rb channel */
+	transport->ops.channel_destroy(chan);
 	list_del(&chan->list);
 	kfree(chan);
 }
@@ -163,6 +212,46 @@ int _ltt_event_destroy(struct ltt_event *event)
 	kmem_cache_free(event);
 }
 
+/**
+ * ltt_transport_register - LTT transport registration
+ * @transport: transport structure
+ *
+ * Registers a transport which can be used as output to extract the data out of
+ * LTTng. The module calling this registration function must ensure that no
+ * trap-inducing code will be executed by the transport functions. E.g.
+ * vmalloc_sync_all() must be called between a vmalloc and the moment the memory
+ * is made visible to the transport function. This registration acts as a
+ * vmalloc_sync_all. Therefore, only if the module allocates virtual memory
+ * after its registration must it synchronize the TLBs.
+ */
+void ltt_transport_register(struct ltt_transport *transport)
+{
+	/*
+	 * Make sure no page fault can be triggered by the module about to be
+	 * registered. We deal with this here so we don't have to call
+	 * vmalloc_sync_all() in each module's init.
+	 */
+	vmalloc_sync_all();
+
+	mutex_lock(&sessions_mutex);
+	list_add_tail(&transport->node, &ltt_transport_list);
+	mutex_unlock(&sessions_mutex);
+}
+EXPORT_SYMBOL_GPL(ltt_transport_register);
+
+/**
+ * ltt_transport_unregister - LTT transport unregistration
+ * @transport: transport structure
+ */
+void ltt_transport_unregister(struct ltt_transport *transport)
+{
+	mutex_lock(&sessions_mutex);
+	list_del(&transport->node);
+	mutex_unlock(&sessions_mutex);
+}
+EXPORT_SYMBOL_GPL(ltt_transport_unregister);
+
+
 static int __init ltt_events_init(void)
 {
 	int ret;
@@ -170,9 +259,6 @@ static int __init ltt_events_init(void)
 	events_cache = KMEM_CACHE(ltt_event, 0);
 	if (!events_cache)
 		return -ENOMEM;
-
-	/* TODO: show ABI to userspace */
-
 	return 0;
 }
 
@@ -180,8 +266,6 @@ static void __exit ltt_events_exit(void)
 {
 	struct ltt_session *session, *tmpsession;
 
-	/* TODO: hide ABI from userspace, wait for callers to release refs. */
-
 	list_for_each_entry_safe(session, tmpsession, &sessions, list)
 		ltt_session_destroy(session);
 	kmem_cache_destroy(events_cache);