Fix: perform volatile load of tracepoint state

[lttng-ust.git] / include / lttng / tracepoint.h

diff --git a/include/lttng/tracepoint.h b/include/lttng/tracepoint.h
index 0327c11dead59e3f0894726b76f4f15120923088..39539911d3b6a12e5a55849013e324958ec4b797 100644 (file)
--- a/include/lttng/tracepoint.h
+++ b/include/lttng/tracepoint.h
@@ -28,6 +28,7 @@
 #include <lttng/tracepoint-types.h>
 #include <lttng/tracepoint-rcu.h>
 #include <urcu/compiler.h>
+#include <urcu/system.h>
 #include <dlfcn.h>     /* for dlopen */
 #include <string.h>    /* for memset */
 #include <lttng/ust-config.h>  /* for sdt */
@@ -47,7 +48,7 @@ extern "C" {
 #define tracepoint(provider, name, ...)                                            \
        do {                                                                \
                STAP_PROBEV(provider, name, ## __VA_ARGS__);                \
-               if (caa_unlikely(__tracepoint_##provider##___##name.state)) \
+               if (caa_unlikely(CMM_LOAD_SHARED(__tracepoint_##provider##___##name.state))) \
                        __tracepoint_cb_##provider##___##name(__VA_ARGS__); \
        } while (0)
 
@@ -145,14 +146,19 @@ extern "C" {
 #define _TP_ARGS_DATA_VAR(...)         _TP_DATA_VAR_N(_TP_NARGS(0, ##__VA_ARGS__), ##__VA_ARGS__)
 #define _TP_PARAMS(...)                        __VA_ARGS__
 
+/*
+ * The tracepoint cb is marked always inline so we can distinguish
+ * between caller's ip addresses within the probe using the return
+ * address.
+ */
 #define _DECLARE_TRACEPOINT(_provider, _name, ...)                                     \
-extern struct tracepoint __tracepoint_##_provider##___##_name;                         \
-static inline lttng_ust_notrace                                                                \
+extern struct lttng_ust_tracepoint __tracepoint_##_provider##___##_name;               \
+static inline __attribute__((always_inline, unused)) lttng_ust_notrace                 \
 void __tracepoint_cb_##_provider##___##_name(_TP_ARGS_PROTO(__VA_ARGS__));             \
-static inline                                                                          \
+static                                                                                 \
 void __tracepoint_cb_##_provider##___##_name(_TP_ARGS_PROTO(__VA_ARGS__))              \
 {                                                                                      \
-       struct tracepoint_probe *__tp_probe;                                            \
+       struct lttng_ust_tracepoint_probe *__tp_probe;                                          \
                                                                                        \
        if (caa_unlikely(!TP_RCU_LINK_TEST()))                                          \
                return;                                                                 \
@@ -161,7 +167,7 @@ void __tracepoint_cb_##_provider##___##_name(_TP_ARGS_PROTO(__VA_ARGS__))           \
        if (caa_unlikely(!__tp_probe))                                                  \
                goto end;                                                               \
        do {                                                                            \
-               void (*__tp_cb)(void) = __tp_probe->func;                                       \
+               void (*__tp_cb)(void) = __tp_probe->func;                               \
                void *__tp_data = __tp_probe->data;                                     \
                                                                                        \
                URCU_FORCE_CAST(void (*)(_TP_ARGS_DATA_PROTO(__VA_ARGS__)), __tp_cb)    \
@@ -199,12 +205,12 @@ extern int __tracepoint_probe_unregister(const char *name, void (*func)(void),
  * tracepoint dynamic linkage handling (callbacks). Hidden visibility:
  * shared across objects in a module/main executable.
  */
-struct tracepoint_dlopen {
+struct lttng_ust_tracepoint_dlopen {
        void *liblttngust_handle;
 
-       int (*tracepoint_register_lib)(struct tracepoint * const *tracepoints_start,
+       int (*tracepoint_register_lib)(struct lttng_ust_tracepoint * const *tracepoints_start,
                int tracepoints_count);
-       int (*tracepoint_unregister_lib)(struct tracepoint * const *tracepoints_start);
+       int (*tracepoint_unregister_lib)(struct lttng_ust_tracepoint * const *tracepoints_start);
 #ifndef _LGPL_SOURCE
        void (*rcu_read_lock_sym_bp)(void);
        void (*rcu_read_unlock_sym_bp)(void);
@@ -212,7 +218,7 @@ struct tracepoint_dlopen {
 #endif
 };
 
-extern struct tracepoint_dlopen tracepoint_dlopen;
+extern struct lttng_ust_tracepoint_dlopen tracepoint_dlopen;
 
 #if defined(TRACEPOINT_DEFINE) || defined(TRACEPOINT_CREATE_PROBES)
 
@@ -225,7 +231,7 @@ int __tracepoint_registered
        __attribute__((weak, visibility("hidden")));
 int __tracepoint_ptrs_registered
        __attribute__((weak, visibility("hidden")));
-struct tracepoint_dlopen tracepoint_dlopen
+struct lttng_ust_tracepoint_dlopen tracepoint_dlopen
        __attribute__((weak, visibility("hidden")));
 
 #ifndef _LGPL_SOURCE
@@ -307,9 +313,9 @@ __tracepoints__destroy(void)
  * registering only _one_ instance of the tracepoints per shared-ojbect
  * (or for the whole main program).
  */
-extern struct tracepoint * const __start___tracepoints_ptrs[]
+extern struct lttng_ust_tracepoint * const __start___tracepoints_ptrs[]
        __attribute__((weak, visibility("hidden")));
-extern struct tracepoint * const __stop___tracepoints_ptrs[]
+extern struct lttng_ust_tracepoint * const __stop___tracepoints_ptrs[]
        __attribute__((weak, visibility("hidden")));
 
 /*
@@ -339,7 +345,7 @@ extern struct tracepoint * const __stop___tracepoints_ptrs[]
        static const char __tp_strtab_##_provider##___##_name[]                 \
                __attribute__((section("__tracepoints_strings"))) =             \
                        #_provider ":" #_name;                                  \
-       struct tracepoint __tracepoint_##_provider##___##_name                  \
+       struct lttng_ust_tracepoint __tracepoint_##_provider##___##_name        \
                __attribute__((section("__tracepoints"))) =                     \
                {                                                               \
                        __tp_strtab_##_provider##___##_name,                    \
@@ -347,8 +353,10 @@ extern struct tracepoint * const __stop___tracepoints_ptrs[]
                        NULL,                                                   \
                        _TRACEPOINT_UNDEFINED_REF(_provider),                   \
                        _TP_EXTRACT_STRING(_args),                              \
+                       { },                                                    \
                };                                                              \
-       static struct tracepoint * __tracepoint_ptr_##_provider##___##_name     \
+       static struct lttng_ust_tracepoint *                                    \
+               __tracepoint_ptr_##_provider##___##_name                        \
                __attribute__((used, section("__tracepoints_ptrs"))) =          \
                        &__tracepoint_##_provider##___##_name;
 
@@ -365,11 +373,11 @@ __tracepoints__ptrs_init(void)
        if (!tracepoint_dlopen.liblttngust_handle)
                return;
        tracepoint_dlopen.tracepoint_register_lib =
-               URCU_FORCE_CAST(int (*)(struct tracepoint * const *, int),
+               URCU_FORCE_CAST(int (*)(struct lttng_ust_tracepoint * const *, int),
                                dlsym(tracepoint_dlopen.liblttngust_handle,
                                        "tracepoint_register_lib"));
        tracepoint_dlopen.tracepoint_unregister_lib =
-               URCU_FORCE_CAST(int (*)(struct tracepoint * const *),
+               URCU_FORCE_CAST(int (*)(struct lttng_ust_tracepoint * const *),
                                dlsym(tracepoint_dlopen.liblttngust_handle,
                                        "tracepoint_unregister_lib"));
        __tracepoint__init_urcu_sym();
@@ -565,7 +573,7 @@ __tracepoints__ptrs_destroy(void)
  * debug information with line-level scope (TRACEPOINT_EVENT default)
  *
  * TRACE_DEBUG           14
- * debug-level message (trace_printf default)
+ * debug-level message
  *
  * Declare tracepoint loglevels for tracepoints. A TRACEPOINT_EVENT
  * should be declared prior to the the TRACEPOINT_LOGLEVEL for a given