Fix: tracepoint header: declare tracepoint_dlopen_ptr
[lttng-ust.git] / include / lttng / tracepoint.h
index e88db89242750c591909fb56ae912eb6cc670ff3..6e3faad6e26c2e3a6220007e8c8afde9ee40996b 100644 (file)
@@ -226,6 +226,22 @@ struct lttng_ust_tracepoint_dlopen {
 };
 
 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;
+}
 
 #if defined(TRACEPOINT_DEFINE) || defined(TRACEPOINT_CREATE_PROBES)
 
@@ -240,6 +256,18 @@ 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
@@ -247,24 +275,26 @@ __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.rcu_read_lock_sym_bp)
-               tracepoint_dlopen.rcu_read_lock_sym_bp =
+       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.liblttngust_handle,
+                               dlsym(tracepoint_dlopen_ptr->liblttngust_handle,
                                        "tp_rcu_read_lock_bp"));
-       if (!tracepoint_dlopen.rcu_read_unlock_sym_bp)
-               tracepoint_dlopen.rcu_read_unlock_sym_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.liblttngust_handle,
+                               dlsym(tracepoint_dlopen_ptr->liblttngust_handle,
                                        "tp_rcu_read_unlock_bp"));
-       if (!tracepoint_dlopen.rcu_dereference_sym_bp)
-               tracepoint_dlopen.rcu_dereference_sym_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.liblttngust_handle,
+                               dlsym(tracepoint_dlopen_ptr->liblttngust_handle,
                                        "tp_rcu_dereference_sym_bp"));
 }
 #else
@@ -284,10 +314,12 @@ __tracepoints__init(void)
        if (__tracepoint_registered++)
                return;
 
-       if (!tracepoint_dlopen.liblttngust_handle)
-               tracepoint_dlopen.liblttngust_handle =
+       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.liblttngust_handle)
+       if (!tracepoint_dlopen_ptr->liblttngust_handle)
                return;
        __tracepoint__init_urcu_sym();
 }
@@ -301,13 +333,17 @@ __tracepoints__destroy(void)
 
        if (--__tracepoint_registered)
                return;
-       if (tracepoint_dlopen.liblttngust_handle && !__tracepoint_ptrs_registered) {
-               ret = dlclose(tracepoint_dlopen.liblttngust_handle);
+       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, 0, sizeof(tracepoint_dlopen));
+               memset(tracepoint_dlopen_ptr, 0, sizeof(*tracepoint_dlopen_ptr));
        }
 }
 
@@ -374,22 +410,24 @@ __tracepoints__ptrs_init(void)
 {
        if (__tracepoint_ptrs_registered++)
                return;
-       if (!tracepoint_dlopen.liblttngust_handle)
-               tracepoint_dlopen.liblttngust_handle =
+       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.liblttngust_handle)
+       if (!tracepoint_dlopen_ptr->liblttngust_handle)
                return;
-       tracepoint_dlopen.tracepoint_register_lib =
+       tracepoint_dlopen_ptr->tracepoint_register_lib =
                URCU_FORCE_CAST(int (*)(struct lttng_ust_tracepoint * const *, int),
-                               dlsym(tracepoint_dlopen.liblttngust_handle,
+                               dlsym(tracepoint_dlopen_ptr->liblttngust_handle,
                                        "tracepoint_register_lib"));
-       tracepoint_dlopen.tracepoint_unregister_lib =
+       tracepoint_dlopen_ptr->tracepoint_unregister_lib =
                URCU_FORCE_CAST(int (*)(struct lttng_ust_tracepoint * const *),
-                               dlsym(tracepoint_dlopen.liblttngust_handle,
+                               dlsym(tracepoint_dlopen_ptr->liblttngust_handle,
                                        "tracepoint_unregister_lib"));
        __tracepoint__init_urcu_sym();
-       if (tracepoint_dlopen.tracepoint_register_lib) {
-               tracepoint_dlopen.tracepoint_register_lib(__start___tracepoints_ptrs,
+       if (tracepoint_dlopen_ptr->tracepoint_register_lib) {
+               tracepoint_dlopen_ptr->tracepoint_register_lib(__start___tracepoints_ptrs,
                                __stop___tracepoints_ptrs -
                                __start___tracepoints_ptrs);
        }
@@ -404,15 +442,19 @@ __tracepoints__ptrs_destroy(void)
 
        if (--__tracepoint_ptrs_registered)
                return;
-       if (tracepoint_dlopen.tracepoint_unregister_lib)
-               tracepoint_dlopen.tracepoint_unregister_lib(__start___tracepoints_ptrs);
-       if (tracepoint_dlopen.liblttngust_handle && !__tracepoint_registered) {
-               ret = dlclose(tracepoint_dlopen.liblttngust_handle);
+       if (!tracepoint_dlopen_ptr)
+               tracepoint_dlopen_ptr = &tracepoint_dlopen;
+       if (tracepoint_dlopen_ptr->tracepoint_unregister_lib)
+               tracepoint_dlopen_ptr->tracepoint_unregister_lib(__start___tracepoints_ptrs);
+       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, 0, sizeof(tracepoint_dlopen));
+               memset(tracepoint_dlopen_ptr, 0, sizeof(*tracepoint_dlopen_ptr));
        }
 }
 
@@ -430,6 +472,50 @@ __tracepoints__ptrs_destroy(void)
 
 /* The following declarations must be outside re-inclusion protection. */
 
+#ifndef TRACEPOINT_ENUM
+
+/*
+ * Tracepoint Enumerations
+ *
+ * The enumeration is a mapping between an integer, or range of integers, and
+ * a string. It can be used to have a more compact trace in cases where the
+ * possible values for a field are limited:
+ *
+ * An example:
+ *
+ * TRACEPOINT_ENUM(someproject_component, enumname,
+ *     TP_ENUM_VALUES(
+ *             ctf_enum_value("even", 0)
+ *             ctf_enum_value("uneven", 1)
+ *             ctf_enum_range("twoto4", 2, 4)
+ *             ctf_enum_value("five", 5)
+ *     )
+ * )
+ *
+ * Where "someproject_component" is the name of the component this enumeration
+ * belongs to and "enumname" identifies this enumeration. Inside the
+ * TP_ENUM_VALUES macro is the actual mapping. Each string value can map
+ * to either a single value with ctf_enum_value or a range of values
+ * with ctf_enum_range.
+ *
+ * Enumeration ranges may overlap, but the behavior is implementation-defined,
+ * each trace reader will handle overlapping as it wishes.
+ *
+ * That enumeration can then be used in a field inside the TP_FIELD macro using
+ * the following line:
+ *
+ * ctf_enum(someproject_component, enumname, enumtype, enumfield, enumval)
+ *
+ * Where "someproject_component" and "enumname" match those in the
+ * TRACEPOINT_ENUM, "enumtype" is a signed or unsigned integer type
+ * backing the enumeration, "enumfield" is the name of the field and
+ * "enumval" is the value.
+ */
+
+#define TRACEPOINT_ENUM(provider, name, values)
+
+#endif /* #ifndef TRACEPOINT_ENUM */
+
 #ifndef TRACEPOINT_EVENT
 
 /*
@@ -453,6 +539,9 @@ __tracepoints__ptrs_destroy(void)
  *         * Integer, printed with 0x base 16 * 
  *         ctf_integer_hex(unsigned long, field_d, arg1)
  *
+ *         * Enumeration *
+ *         ctf_enum(someproject_component, enum_name, int, field_e, arg0)
+ *
  *         * Array Sequence, printed as UTF8-encoded array of bytes * 
  *         ctf_array_text(char, field_b, string, FIXED_LEN)
  *         ctf_sequence_text(char, field_c, string, size_t, strlen)
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