jump label: Introduce static_branch() interface

[deliverable/linux.git] / include / linux / tracepoint.h

diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h
index c6814616653b1ff4d385b8b4148c4b2b14847e31..d530a4460a0b96d4a73ebfb1a65e7fe32547f210 100644 (file)
--- a/include/linux/tracepoint.h
+++ b/include/linux/tracepoint.h
@@ -29,16 +29,11 @@ struct tracepoint_func {
 
 struct tracepoint {
        const char *name;               /* Tracepoint name */
-       int state;                      /* State. */
+       struct jump_label_key key;
        void (*regfunc)(void);
        void (*unregfunc)(void);
        struct tracepoint_func __rcu *funcs;
-} __attribute__((aligned(32)));                /*
-                                        * Aligned on 32 bytes because it is
-                                        * globally visible and gcc happily
-                                        * align these on the structure size.
-                                        * Keep in sync with vmlinux.lds.h.
-                                        */
+};
 
 /*
  * Connect a probe to a tracepoint.
@@ -61,15 +56,15 @@ extern void tracepoint_probe_update_all(void);
 
 struct tracepoint_iter {
        struct module *module;
-       struct tracepoint *tracepoint;
+       struct tracepoint * const *tracepoint;
 };
 
 extern void tracepoint_iter_start(struct tracepoint_iter *iter);
 extern void tracepoint_iter_next(struct tracepoint_iter *iter);
 extern void tracepoint_iter_stop(struct tracepoint_iter *iter);
 extern void tracepoint_iter_reset(struct tracepoint_iter *iter);
-extern int tracepoint_get_iter_range(struct tracepoint **tracepoint,
-       struct tracepoint *begin, struct tracepoint *end);
+extern int tracepoint_get_iter_range(struct tracepoint * const **tracepoint,
+       struct tracepoint * const *begin, struct tracepoint * const *end);
 
 /*
  * tracepoint_synchronize_unregister must be called between the last tracepoint
@@ -84,11 +79,13 @@ static inline void tracepoint_synchronize_unregister(void)
 #define PARAMS(args...) args
 
 #ifdef CONFIG_TRACEPOINTS
-extern void tracepoint_update_probe_range(struct tracepoint *begin,
-       struct tracepoint *end);
+extern
+void tracepoint_update_probe_range(struct tracepoint * const *begin,
+       struct tracepoint * const *end);
 #else
-static inline void tracepoint_update_probe_range(struct tracepoint *begin,
-       struct tracepoint *end)
+static inline
+void tracepoint_update_probe_range(struct tracepoint * const *begin,
+       struct tracepoint * const *end)
 { }
 #endif /* CONFIG_TRACEPOINTS */
 
@@ -149,9 +146,7 @@ static inline void tracepoint_update_probe_range(struct tracepoint *begin,
        extern struct tracepoint __tracepoint_##name;                   \
        static inline void trace_##name(proto)                          \
        {                                                               \
-               JUMP_LABEL(&__tracepoint_##name.state, do_trace);       \
-               return;                                                 \
-do_trace:                                                              \
+               if (static_branch(&__tracepoint_##name.key))            \
                        __DO_TRACE(&__tracepoint_##name,                \
                                TP_PROTO(data_proto),                   \
                                TP_ARGS(data_args),                     \
@@ -174,12 +169,20 @@ do_trace:                                                         \
        {                                                               \
        }
 
-#define DEFINE_TRACE_FN(name, reg, unreg)                              \
-       static const char __tpstrtab_##name[]                           \
-       __attribute__((section("__tracepoints_strings"))) = #name;      \
-       struct tracepoint __tracepoint_##name                           \
-       __attribute__((section("__tracepoints"), aligned(32))) =        \
-               { __tpstrtab_##name, 0, reg, unreg, NULL }
+/*
+ * We have no guarantee that gcc and the linker won't up-align the tracepoint
+ * structures, so we create an array of pointers that will be used for iteration
+ * on the tracepoints.
+ */
+#define DEFINE_TRACE_FN(name, reg, unreg)                               \
+       static const char __tpstrtab_##name[]                            \
+       __attribute__((section("__tracepoints_strings"))) = #name;       \
+       struct tracepoint __tracepoint_##name                            \
+       __attribute__((section("__tracepoints"))) =                      \
+               { __tpstrtab_##name, JUMP_LABEL_INIT, reg, unreg, NULL };\
+       static struct tracepoint * const __tracepoint_ptr_##name __used  \
+       __attribute__((section("__tracepoints_ptrs"))) =                 \
+               &__tracepoint_##name;
 
 #define DEFINE_TRACE(name)                                             \
        DEFINE_TRACE_FN(name, NULL, NULL);