Refactoring: struct lttng_bytecode_runtime

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

diff --git a/include/lttng/ust-events.h b/include/lttng/ust-events.h
index c928fadb246c0ed5ff7fac57878987757348b91a..13ecb6d7f05077d4e4bd2ef883b5485630f4f5f4 100644 (file)
--- a/include/lttng/ust-events.h
+++ b/include/lttng/ust-events.h
@@ -362,14 +362,18 @@ struct lttng_interpreter_output;
 struct lttng_ust_bytecode_runtime_private;
 
 /*
- * This structure is used in the probes. More specifically, the
- * `interpreter_funcs` and `node` fields are explicity used in the
- * probes. When modifying this structure we must not change the layout
- * of these two fields as it is considered ABI.
+ * IMPORTANT: this structure is part of the ABI between the probe and
+ * UST. Fields need to be only added at the end, never reordered, never
+ * removed.
+ *
+ * The field @struct_size should be used to determine the size of the
+ * structure. It should be queried before using additional fields added
+ * at the end of the structure.
  */
-struct lttng_bytecode_runtime {
-       struct lttng_ust_bytecode_runtime_private *priv;
+struct lttng_ust_bytecode_runtime {
+       uint32_t struct_size;                   /* Size of this structure. */
 
+       struct lttng_ust_bytecode_runtime_private *priv;
        /* Associated bytecode */
        union {
                uint64_t (*filter)(void *interpreter_data,
@@ -379,6 +383,8 @@ struct lttng_bytecode_runtime {
                                struct lttng_interpreter_output *interpreter_output);
        } interpreter_funcs;
        struct cds_list_head node;      /* list of bytecode runtime in event */
+
+       /* End of base ABI. Fields below should be used after checking struct_size. */
 };
 
 /*
@@ -421,7 +427,7 @@ struct lttng_ust_event_common {
 
        int enabled;
        int has_enablers_without_bytecode;
-       /* list of struct lttng_bytecode_runtime, sorted by seqnum */
+       /* list of struct lttng_ust_bytecode_runtime, sorted by seqnum */
        struct cds_list_head filter_bytecode_runtime_head;
 
        /* End of base ABI. Fields below should be used after checking struct_size. */