X-Git-Url: https://git.liburcu.org/?p=ust.git;a=blobdiff_plain;f=libust%2Ftrace_event.c;h=854a7676b3586d10b84ece785eb97cb65f2aec3d;hp=d0d9ec455e36c132f8b3eed065517940f63583b3;hb=HEAD;hpb=fc1caebc8a71283c7766549ebed47300d1b52945

diff --git a/libust/trace_event.c b/libust/trace_event.c
index d0d9ec4..854a767 100644
--- a/libust/trace_event.c
+++ b/libust/trace_event.c
@@ -3,8 +3,8 @@
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
- * License as published by the Free Software Foundation; either
- * version 2.1 of the License, or (at your option) any later version.
+ * License as published by the Free Software Foundation;
+ * version 2.1 of the License.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ -17,31 +17,45 @@
  *
  */
 
+#define _LGPL_SOURCE
 #include <errno.h>
 #include <ust/tracepoint.h>
+#include <ust/tracepoint-internal.h>
 #include <ust/core.h>
 #include <ust/kcompat/kcompat.h>
-#include "usterr.h"
-
-#define _LGPL_SOURCE
 #include <urcu-bp.h>
 
+#include "usterr_signal_safe.h"
+
 /* libraries that contain trace_events (struct trace_event_lib) */
 static CDS_LIST_HEAD(libs);
-
+/*
+ * Nested mutex is not required here, but provide the same guaranteed
+ * for start/stop iteration vs nested ops as markers and tracepoints.
+ */
+static __thread int nested_mutex;
 static DEFINE_MUTEX(trace_events_mutex);
 
+static
+int trace_event_get_iter_range(struct trace_event * const **trace_event,
+	struct trace_event * const *begin,
+	struct trace_event * const *end);
+
+static
 void lock_trace_events(void)
 {
-	pthread_mutex_lock(&trace_events_mutex);
+	if (!(nested_mutex++))
+		pthread_mutex_lock(&trace_events_mutex);
 }
 
+static
 void unlock_trace_events(void)
 {
-	pthread_mutex_unlock(&trace_events_mutex);
+	if (!(--nested_mutex))
+		pthread_mutex_unlock(&trace_events_mutex);
 }
 
-
+static
 int lib_get_iter_trace_events(struct trace_event_iter *iter)
 {
 	struct trace_event_lib *iter_lib;
@@ -71,17 +85,21 @@ int lib_get_iter_trace_events(struct trace_event_iter *iter)
  *
  * Returns whether a next trace_event has been found (1) or not (0).
  * Will return the first trace_event in the range if the input trace_event is NULL.
+ * Called with trace event mutex held.
  */
+static
 int trace_event_get_iter_range(struct trace_event * const **trace_event,
 	struct trace_event * const *begin,
 	struct trace_event * const *end)
 {
-	if (!*trace_event && begin != end) {
+	if (!*trace_event && begin != end)
 		*trace_event = begin;
-		return 1;
+	while (*trace_event >= begin && *trace_event < end) {
+		if (!**trace_event)
+			(*trace_event)++;	/* skip dummy */
+		else
+			return 1;
 	}
-	if (*trace_event >= begin && *trace_event < end)
-		return 1;
 	return 0;
 }
 
@@ -97,9 +115,13 @@ static void trace_event_get_iter(struct trace_event_iter *iter)
 
 void trace_event_iter_start(struct trace_event_iter *iter)
 {
+	lock_trace_events();
 	trace_event_get_iter(iter);
 }
 
+/*
+ * Called with trace event mutex held.
+ */
 void trace_event_iter_next(struct trace_event_iter *iter)
 {
 	iter->trace_event++;
@@ -111,6 +133,11 @@ void trace_event_iter_next(struct trace_event_iter *iter)
 	trace_event_get_iter(iter);
 }
 
+void trace_event_iter_stop(struct trace_event_iter *iter)
+{
+	unlock_trace_events();
+}
+
 void trace_event_iter_reset(struct trace_event_iter *iter)
 {
 	iter->lib = NULL;
@@ -120,19 +147,32 @@ void trace_event_iter_reset(struct trace_event_iter *iter)
 int trace_event_register_lib(struct trace_event * const *trace_events_start,
 			     int trace_events_count)
 {
-	struct trace_event_lib *pl;
+	struct trace_event_lib *pl, *iter;
 
 	pl = (struct trace_event_lib *) malloc(sizeof(struct trace_event_lib));
 
 	pl->trace_events_start = trace_events_start;
 	pl->trace_events_count = trace_events_count;
 
-	/* FIXME: maybe protect this with its own mutex? */
-	pthread_mutex_lock(&trace_events_mutex);
+	lock_trace_events();
+	/*
+	 * We sort the libs by struct lib pointer address.
+	 */
+	cds_list_for_each_entry_reverse(iter, &libs, list) {
+		BUG_ON(iter == pl);    /* Should never be in the list twice */
+		if (iter < pl) {
+			/* We belong to the location right after iter. */
+			cds_list_add(&pl->list, &iter->list);
+			goto lib_added;
+		}
+	}
+	/* We should be added at the head of the list */
 	cds_list_add(&pl->list, &libs);
-	pthread_mutex_unlock(&trace_events_mutex);
+lib_added:
+	unlock_trace_events();
 
-	DBG("just registered a trace_events section from %p and having %d trace_events", trace_events_start, trace_events_count);
+	/* trace_events_count - 1: skip dummy */
+	DBG("just registered a trace_events section from %p and having %d trace_events (minus dummy trace_event)", trace_events_start, trace_events_count);
 
 	return 0;
 }
@@ -141,8 +181,7 @@ int trace_event_unregister_lib(struct trace_event * const *trace_events_start)
 {
 	struct trace_event_lib *lib;
 
-	pthread_mutex_lock(&trace_events_mutex);
-
+	unlock_trace_events();
 	cds_list_for_each_entry(lib, &libs, list) {
 		if(lib->trace_events_start == trace_events_start) {
 			struct trace_event_lib *lib2free = lib;
@@ -151,8 +190,7 @@ int trace_event_unregister_lib(struct trace_event * const *trace_events_start)
 			break;
 		}
 	}
-
-	pthread_mutex_unlock(&trace_events_mutex);
+	unlock_trace_events();
 
 	return 0;
 }