From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Fri, 17 Feb 2023 21:08:46 +0000 (-0500)
Subject: Fix: trace events in C constructors/destructors
X-Git-Tag: v2.12.8~3
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=a8fafb675a9f580f6a889223e26664ea11cb0c99;p=lttng-ust.git

Fix: trace events in C constructors/destructors

Adding a priority (150) to the tracepoint and tracepoint provider
constructors/destructors ensures that we trace tracepoints located
within C constructors/destructors with a higher priority value,
including the default init priority of 65535, when the tracepoint vs
tracepoint definition vs tracepoint probe provider are in different
compile units (and in various link order one compared to another).

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: Ia8e36317ae058402cdb81cb921da69cfa97a2f82
---

diff --git a/include/lttng/tracepoint.h b/include/lttng/tracepoint.h
index 1cf02188..56249f6e 100644
--- a/include/lttng/tracepoint.h
+++ b/include/lttng/tracepoint.h
@@ -333,7 +333,7 @@ __tracepoint__init_urcu_sym(void)
 }
 #endif
 
-static void lttng_ust_notrace __attribute__((constructor))
+static void lttng_ust_notrace __attribute__((constructor(LTTNG_UST_CONSTRUCTOR_PRIO)))
 __tracepoints__init(void);
 static void
 __tracepoints__init(void)
@@ -355,7 +355,7 @@ __tracepoints__init(void)
 	__tracepoint__init_urcu_sym();
 }
 
-static void lttng_ust_notrace __attribute__((destructor))
+static void lttng_ust_notrace __attribute__((destructor(LTTNG_UST_CONSTRUCTOR_PRIO)))
 __tracepoints__destroy(void);
 static void
 __tracepoints__destroy(void)
@@ -460,7 +460,7 @@ extern struct lttng_ust_tracepoint * const __stop___tracepoints_ptrs[]
 		__lttng_ust_variable_attribute_no_sanitize_address =		\
 			&__tracepoint_##_provider##___##_name;
 
-static void lttng_ust_notrace __attribute__((constructor))
+static void lttng_ust_notrace __attribute__((constructor(LTTNG_UST_CONSTRUCTOR_PRIO)))
 __tracepoints__ptrs_init(void);
 static void
 __tracepoints__ptrs_init(void)
@@ -504,7 +504,7 @@ __tracepoints__ptrs_init(void)
 	}
 }
 
-static void lttng_ust_notrace __attribute__((destructor))
+static void lttng_ust_notrace __attribute__((destructor(LTTNG_UST_CONSTRUCTOR_PRIO)))
 __tracepoints__ptrs_destroy(void);
 static void
 __tracepoints__ptrs_destroy(void)
diff --git a/include/lttng/ust-compiler.h b/include/lttng/ust-compiler.h
index 31eaf73c..7e9aa497 100644
--- a/include/lttng/ust-compiler.h
+++ b/include/lttng/ust-compiler.h
@@ -24,6 +24,16 @@
  * SOFTWARE.
  */
 
+/*
+ * By default, LTTng-UST uses the priority 150 for the tracepoint and probe
+ * provider constructors to trace tracepoints located within
+ * constructors/destructors with a higher priority value within the same
+ * module. This priority can be overridden by the application.
+ */
+#ifndef LTTNG_UST_CONSTRUCTOR_PRIO
+#define LTTNG_UST_CONSTRUCTOR_PRIO	150
+#endif
+
 #define lttng_ust_notrace __attribute__((no_instrument_function))
 #define LTTNG_PACKED	__attribute__((__packed__))
 
diff --git a/include/lttng/ust-tracepoint-event.h b/include/lttng/ust-tracepoint-event.h
index da52162c..80906feb 100644
--- a/include/lttng/ust-tracepoint-event.h
+++ b/include/lttng/ust-tracepoint-event.h
@@ -1017,7 +1017,7 @@ static int _TP_COMBINE_TOKENS(__probe_register_refcount___, TRACEPOINT_PROVIDER)
 
 /* Reset all macros within TRACEPOINT_EVENT */
 #include <lttng/ust-tracepoint-event-reset.h>
-static void lttng_ust_notrace __attribute__((constructor))
+static void lttng_ust_notrace __attribute__((constructor(LTTNG_UST_CONSTRUCTOR_PRIO)))
 _TP_COMBINE_TOKENS(__lttng_events_init__, TRACEPOINT_PROVIDER)(void);
 static void
 _TP_COMBINE_TOKENS(__lttng_events_init__, TRACEPOINT_PROVIDER)(void)
@@ -1044,7 +1044,7 @@ _TP_COMBINE_TOKENS(__lttng_events_init__, TRACEPOINT_PROVIDER)(void)
 	}
 }
 
-static void lttng_ust_notrace __attribute__((destructor))
+static void lttng_ust_notrace __attribute__((destructor(LTTNG_UST_CONSTRUCTOR_PRIO)))
 _TP_COMBINE_TOKENS(__lttng_events_exit__, TRACEPOINT_PROVIDER)(void);
 static void
 _TP_COMBINE_TOKENS(__lttng_events_exit__, TRACEPOINT_PROVIDER)(void)