+extern struct lttng_ust_tracepoint_dlopen tracepoint_dlopen;
+extern struct lttng_ust_tracepoint_dlopen *tracepoint_dlopen_ptr;
+
+/* Disable tracepoint destructors. */
+int __tracepoints__disable_destructors __attribute__((weak));
+
+/*
+ * Programs that have threads that survive after they exit, and
+ * therefore call library destructors, should disable the tracepoint
+ * destructors by calling tracepoint_disable_destructors(). This will
+ * leak the tracepoint instrumentation library shared object, leaving
+ * its teardown to the operating system process teardown.
+ */
+static inline void tracepoint_disable_destructors(void)
+{
+ __tracepoints__disable_destructors = 1;
+}
+
+/*
+ * These weak symbols, the constructor, and destructor take care of
+ * registering only _one_ instance of the tracepoints per shared-ojbect
+ * (or for the whole main program).
+ */
+int __tracepoint_registered
+ __attribute__((weak, visibility("hidden")));
+int __tracepoint_ptrs_registered
+ __attribute__((weak, visibility("hidden")));
+struct lttng_ust_tracepoint_dlopen tracepoint_dlopen
+ __attribute__((weak, visibility("hidden")));
+/*
+ * Deal with gcc O1 optimisation issues with weak hidden symbols. gcc
+ * 4.8 and prior does not have the same behavior for symbol scoping on
+ * 32-bit powerpc depending on the object size: symbols for objects of 8
+ * bytes or less have the same address throughout a module, whereas they
+ * have different addresses between compile units for objects larger
+ * than 8 bytes. Add this pointer indirection to ensure that the symbol
+ * scoping match that of the other weak hidden symbols found in this
+ * header.
+ */
+struct lttng_ust_tracepoint_dlopen *tracepoint_dlopen_ptr
+ __attribute__((weak, visibility("hidden")));
+
+#ifndef _LGPL_SOURCE
+static inline void lttng_ust_notrace
+__tracepoint__init_urcu_sym(void);
+static inline void
+__tracepoint__init_urcu_sym(void)
+{
+ if (!tracepoint_dlopen_ptr)
+ tracepoint_dlopen_ptr = &tracepoint_dlopen;
+ /*
+ * Symbols below are needed by tracepoint call sites and probe
+ * providers.
+ */
+ if (!tracepoint_dlopen_ptr->rcu_read_lock_sym_bp)
+ tracepoint_dlopen_ptr->rcu_read_lock_sym_bp =
+ URCU_FORCE_CAST(void (*)(void),
+ dlsym(tracepoint_dlopen_ptr->liblttngust_handle,
+ "tp_rcu_read_lock_bp"));
+ if (!tracepoint_dlopen_ptr->rcu_read_unlock_sym_bp)
+ tracepoint_dlopen_ptr->rcu_read_unlock_sym_bp =
+ URCU_FORCE_CAST(void (*)(void),
+ dlsym(tracepoint_dlopen_ptr->liblttngust_handle,
+ "tp_rcu_read_unlock_bp"));
+ if (!tracepoint_dlopen_ptr->rcu_dereference_sym_bp)
+ tracepoint_dlopen_ptr->rcu_dereference_sym_bp =
+ URCU_FORCE_CAST(void *(*)(void *p),
+ dlsym(tracepoint_dlopen_ptr->liblttngust_handle,
+ "tp_rcu_dereference_sym_bp"));
+}
+#else
+static inline void lttng_ust_notrace
+__tracepoint__init_urcu_sym(void);
+static inline void
+__tracepoint__init_urcu_sym(void)
+{
+}
+#endif
+
+static void lttng_ust_notrace __attribute__((constructor))
+__tracepoints__init(void);
+static void
+__tracepoints__init(void)
+{
+ if (__tracepoint_registered++) {
+ if (!tracepoint_dlopen_ptr->liblttngust_handle)
+ return;
+ __tracepoint__init_urcu_sym();
+ return;
+ }
+
+ if (!tracepoint_dlopen_ptr)
+ tracepoint_dlopen_ptr = &tracepoint_dlopen;
+ if (!tracepoint_dlopen_ptr->liblttngust_handle)
+ tracepoint_dlopen_ptr->liblttngust_handle =
+ dlopen("liblttng-ust-tracepoint.so.0", RTLD_NOW | RTLD_GLOBAL);
+ if (!tracepoint_dlopen_ptr->liblttngust_handle)
+ return;
+ __tracepoint__init_urcu_sym();
+}
+
+static void lttng_ust_notrace __attribute__((destructor))
+__tracepoints__destroy(void);
+static void
+__tracepoints__destroy(void)
+{
+ int ret;
+
+ if (--__tracepoint_registered)
+ return;
+ if (!tracepoint_dlopen_ptr)
+ tracepoint_dlopen_ptr = &tracepoint_dlopen;
+ if (!__tracepoints__disable_destructors
+ && tracepoint_dlopen_ptr->liblttngust_handle
+ && !__tracepoint_ptrs_registered) {
+ ret = dlclose(tracepoint_dlopen_ptr->liblttngust_handle);
+ if (ret) {
+ fprintf(stderr, "Error (%d) in dlclose\n", ret);
+ abort();
+ }
+ memset(tracepoint_dlopen_ptr, 0, sizeof(*tracepoint_dlopen_ptr));
+ }
+}