Refactoring: struct lttng_enum_desc and lttng_enum_entry

- Namespace these structures with lttng_ust_ prefix,
- Use struct_size extensibility scheme,
- Remove padding,
- Use an array of pointers to structure rather than array of enumeration
  entries to allow easier handling of extensibility. This is achieved by
  using __LTTNG_COMPOUND_LITERAL().

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I2bf6e24e22c9646fc321f6c7c9ffcbd32ed22da0

diff --git a/include/lttng/ust-events.h b/include/lttng/ust-events.h
index acea99105a86492646723732f930cc8fe250ab85..164c82c4c8288617702a56edc5eec30ba341b6aa 100644 (file)
--- a/include/lttng/ust-events.h
+++ b/include/lttng/ust-events.h
@@ -83,16 +83,26 @@ enum lttng_enum_entry_options {
        LTTNG_ENUM_ENTRY_OPTION_IS_AUTO = 1U << 0,
 };
 
-#define LTTNG_UST_ENUM_ENTRY_PADDING   16
-struct lttng_enum_entry {
+/*
+ * Enumeration entry description
+ *
+ * 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_ust_enum_entry {
+       uint32_t struct_size;
+
        struct lttng_enum_value start, end; /* start and end are inclusive */
        const char *string;
-       union {
-               struct {
-                       unsigned int options;
-               } LTTNG_PACKED extra;
-               char padding[LTTNG_UST_ENUM_ENTRY_PADDING];
-       } u;
+       unsigned int options;
+
+       /* End of base ABI. Fields below should be used after checking struct_size. */
 };
 
 #define __type_integer(_type, _byte_order, _base, _encoding)   \
@@ -168,7 +178,7 @@ struct lttng_type {
                        enum lttng_string_encodings encoding;
                } string;
                struct {
-                       const struct lttng_enum_desc *desc;     /* Enumeration mapping */
+                       const struct lttng_ust_enum_desc *desc; /* Enumeration mapping */
                        struct lttng_type *container_type;
                } enum_nestable;
                struct {
@@ -191,12 +201,26 @@ struct lttng_type {
        } u;
 };
 
-#define LTTNG_UST_ENUM_TYPE_PADDING    24
-struct lttng_enum_desc {
+/*
+ * Enumeration description
+ *
+ * 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_ust_enum_desc {
+       uint32_t struct_size;
+
        const char *name;
-       const struct lttng_enum_entry *entries;
+       const struct lttng_ust_enum_entry **entries;
        unsigned int nr_entries;
-       char padding[LTTNG_UST_ENUM_TYPE_PADDING];
+
+       /* End of base ABI. Fields below should be used after checking struct_size. */
 };
 
 /*
@@ -460,7 +484,7 @@ struct lttng_ust_event_notifier {
 };
 
 struct lttng_enum {
-       const struct lttng_enum_desc *desc;
+       const struct lttng_ust_enum_desc *desc;
        struct lttng_session *session;
        struct cds_list_head node;      /* Enum list in session */
        struct cds_hlist_node hlist;    /* Session ht of enums */

diff --git a/include/lttng/ust-tracepoint-event.h b/include/lttng/ust-tracepoint-event.h
index 872dfa57bb5b3fa5ff1f6ce9992efb25baefc084..e743ffdad43a6982b87a6ca35a69cfb0c436ba52 100644 (file)
--- a/include/lttng/ust-tracepoint-event.h
+++ b/include/lttng/ust-tracepoint-event.h
@@ -147,7 +147,8 @@ void __event_template_proto___##_provider##___##_name(_TP_ARGS_DATA_PROTO(_args)
 /* Enumeration entry (single value) */
 #undef ctf_enum_value
 #define ctf_enum_value(_string, _value)                                        \
-       {                                                               \
+       __LTTNG_COMPOUND_LITERAL(struct lttng_ust_enum_entry, {         \
+               .struct_size = sizeof(struct lttng_ust_enum_entry),             \
                .start = {                                              \
                        .value = lttng_is_signed_type(__typeof__(_value)) ? \
                                (long long) (_value) : (_value),        \
@@ -159,12 +160,13 @@ void __event_template_proto___##_provider##___##_name(_TP_ARGS_DATA_PROTO(_args)
                        .signedness = lttng_is_signed_type(__typeof__(_value)), \
                },                                                      \
                .string = (_string),                                    \
-       },
+       }),
 
 /* Enumeration entry (range) */
 #undef ctf_enum_range
 #define ctf_enum_range(_string, _range_start, _range_end)              \
-       {                                                               \
+       __LTTNG_COMPOUND_LITERAL(struct lttng_ust_enum_entry, {         \
+               .struct_size = sizeof(struct lttng_ust_enum_entry),             \
                .start = {                                              \
                        .value = lttng_is_signed_type(__typeof__(_range_start)) ? \
                                (long long) (_range_start) : (_range_start), \
@@ -176,12 +178,13 @@ void __event_template_proto___##_provider##___##_name(_TP_ARGS_DATA_PROTO(_args)
                        .signedness = lttng_is_signed_type(__typeof__(_range_end)), \
                },                                                      \
                .string = (_string),                                    \
-       },
+       }),
 
 /* Enumeration entry (automatic value; follows the rules of CTF) */
 #undef ctf_enum_auto
-#define ctf_enum_auto(_string)                                 \
-       {                                                               \
+#define ctf_enum_auto(_string)                                         \
+       __LTTNG_COMPOUND_LITERAL(struct lttng_ust_enum_entry, {         \
+               .struct_size = sizeof(struct lttng_ust_enum_entry),             \
                .start = {                                              \
                        .value = -1ULL,                                 \
                        .signedness = 0,                                \
@@ -191,12 +194,8 @@ void __event_template_proto___##_provider##___##_name(_TP_ARGS_DATA_PROTO(_args)
                        .signedness = 0,                                \
                },                                                      \
                .string = (_string),                                    \
-               .u = {                                                  \
-                       .extra = {                                      \
-                               .options = LTTNG_ENUM_ENTRY_OPTION_IS_AUTO, \
-                       },                                              \
-               },                                                      \
-       },
+               .options = LTTNG_ENUM_ENTRY_OPTION_IS_AUTO,             \
+       }),
 
 #undef TP_ENUM_VALUES
 #define TP_ENUM_VALUES(...)                                            \
@@ -204,7 +203,7 @@ void __event_template_proto___##_provider##___##_name(_TP_ARGS_DATA_PROTO(_args)
 
 #undef TRACEPOINT_ENUM
 #define TRACEPOINT_ENUM(_provider, _name, _values)                     \
-       const struct lttng_enum_entry __enum_values__##_provider##_##_name[] = { \
+       const struct lttng_ust_enum_entry *__enum_values__##_provider##_##_name[] = { \
                _values                                                 \
                ctf_enum_value("", 0)   /* Dummy, 0-len array forbidden by C99. */ \
        };
@@ -370,7 +369,8 @@ void __event_template_proto___##_provider##___##_name(_TP_ARGS_DATA_PROTO(_args)
 
 #undef TRACEPOINT_ENUM
 #define TRACEPOINT_ENUM(_provider, _name, _values)                                     \
-       static const struct lttng_enum_desc __enum_##_provider##_##_name = {            \
+       static const struct lttng_ust_enum_desc __enum_##_provider##_##_name = {                \
+               .struct_size = sizeof(struct lttng_ust_enum_desc),                              \
                .name = #_provider "_" #_name,                                          \
                .entries = __enum_values__##_provider##_##_name,                        \
                .nr_entries = _TP_ARRAY_SIZE(__enum_values__##_provider##_##_name) - 1, \

diff --git a/include/ust-comm.h b/include/ust-comm.h
index 3d1ba3729c173a40b2d28b3713cec5ed137582bf..aaf7c6ef76e7e0f51cbc2b798b2cee1276f5690f 100644 (file)
--- a/include/ust-comm.h
+++ b/include/ust-comm.h
@@ -44,7 +44,7 @@
 
 struct lttng_ust_event_field;
 struct lttng_ctx_field;
-struct lttng_enum_entry;
+struct lttng_ust_enum_entry;
 struct lttng_integer_type;
 struct lttng_session;
 
@@ -292,7 +292,7 @@ int ustcomm_register_enum(int sock,
        int session_objd,               /* session descriptor */
        const char *enum_name,          /* enum name (input) */
        size_t nr_entries,              /* entries */
-       const struct lttng_enum_entry *entries,
+       const struct lttng_ust_enum_entry **entries,
        uint64_t *id);                  /* enum id (output) */
 
 /*

diff --git a/liblttng-ust-comm/lttng-ust-comm.c b/liblttng-ust-comm/lttng-ust-comm.c
index e0b7d73bf9c33e763e6c2232eb31fd6e8a70e9e5..656e170b100a8f0694b1ff3c37d2b324079204f2 100644 (file)
--- a/liblttng-ust-comm/lttng-ust-comm.c
+++ b/liblttng-ust-comm/lttng-ust-comm.c
@@ -1303,7 +1303,7 @@ error_type:
 static
 int serialize_entries(struct ustctl_enum_entry **_entries,
                size_t nr_entries,
-               const struct lttng_enum_entry *lttng_entries)
+               const struct lttng_ust_enum_entry **lttng_entries)
 {
        struct ustctl_enum_entry *entries;
        int i;
@@ -1314,10 +1314,10 @@ int serialize_entries(struct ustctl_enum_entry **_entries,
                return -ENOMEM;
        for (i = 0; i < nr_entries; i++) {
                struct ustctl_enum_entry *uentry;
-               const struct lttng_enum_entry *lentry;
+               const struct lttng_ust_enum_entry *lentry;
 
                uentry = &entries[i];
-               lentry = &lttng_entries[i];
+               lentry = lttng_entries[i];
 
                uentry->start.value = lentry->start.value;
                uentry->start.signedness = lentry->start.signedness;
@@ -1326,7 +1326,7 @@ int serialize_entries(struct ustctl_enum_entry **_entries,
                strncpy(uentry->string, lentry->string, LTTNG_UST_ABI_SYM_NAME_LEN);
                uentry->string[LTTNG_UST_ABI_SYM_NAME_LEN - 1] = '\0';
 
-               if (lentry->u.extra.options & LTTNG_ENUM_ENTRY_OPTION_IS_AUTO) {
+               if (lentry->options & LTTNG_ENUM_ENTRY_OPTION_IS_AUTO) {
                        uentry->u.extra.options |=
                                USTCTL_UST_ENUM_ENTRY_OPTION_IS_AUTO;
                }
@@ -1523,7 +1523,7 @@ int ustcomm_register_enum(int sock,
        int session_objd,               /* session descriptor */
        const char *enum_name,          /* enum name (input) */
        size_t nr_entries,              /* entries */
-       const struct lttng_enum_entry *lttng_entries,
+       const struct lttng_ust_enum_entry **lttng_entries,
        uint64_t *id)
 {
        ssize_t len;

diff --git a/liblttng-ust/lttng-events.c b/liblttng-ust/lttng-events.c
index 3c78734fe22bb1e433add84861e0ae5012cecc27..762395d657330b0aca25959661d8d2ebe587bb53 100644 (file)
--- a/liblttng-ust/lttng-events.c
+++ b/liblttng-ust/lttng-events.c
@@ -398,7 +398,7 @@ void lttng_enabler_destroy(struct lttng_enabler *enabler)
 }
 
 static
-int lttng_enum_create(const struct lttng_enum_desc *desc,
+int lttng_enum_create(const struct lttng_ust_enum_desc *desc,
                struct lttng_session *session)
 {
        const char *enum_name = desc->name;
@@ -462,7 +462,7 @@ int lttng_create_enum_check(const struct lttng_type *type,
        switch (type->atype) {
        case atype_enum_nestable:
        {
-               const struct lttng_enum_desc *enum_desc;
+               const struct lttng_ust_enum_desc *enum_desc;
                int ret;
 
                enum_desc = type->u.enum_nestable.desc;
@@ -476,7 +476,7 @@ int lttng_create_enum_check(const struct lttng_type *type,
        case atype_dynamic:
        {
                const struct lttng_ust_event_field *tag_field_generic;
-               const struct lttng_enum_desc *enum_desc;
+               const struct lttng_ust_enum_desc *enum_desc;
                int ret;
 
                tag_field_generic = lttng_ust_dynamic_type_tag_field();
@@ -1140,7 +1140,7 @@ void _event_enum_destroy(struct lttng_ust_event_common *event)
 
                /* Destroy enums of the current event. */
                for (i = 0; i < event_recorder->parent->priv->desc->nr_fields; i++) {
-                       const struct lttng_enum_desc *enum_desc;
+                       const struct lttng_ust_enum_desc *enum_desc;
                        const struct lttng_ust_event_field *field;
                        struct lttng_enum *curr_enum;
 

diff --git a/liblttng-ust/lttng-ust-dynamic-type.c b/liblttng-ust/lttng-ust-dynamic-type.c
index 1647094f4f6256c38d458150ebea23dfb605794c..ccda6475d7a773793aeaaee05f44f8b27cb5b605 100644 (file)
--- a/liblttng-ust/lttng-ust-dynamic-type.c
+++ b/liblttng-ust/lttng-ust-dynamic-type.c
@@ -16,7 +16,8 @@
 #include <ust-dynamic-type.h>
 
 #define ctf_enum_value(_string, _value)                                        \
-       {                                                               \
+       __LTTNG_COMPOUND_LITERAL(struct lttng_ust_enum_entry, {         \
+               .struct_size = sizeof(struct lttng_ust_enum_entry),             \
                .start = {                                              \
                        .signedness = lttng_is_signed_type(__typeof__(_value)), \
                        .value = lttng_is_signed_type(__typeof__(_value)) ? \
@@ -28,9 +29,9 @@
                                (long long) (_value) : (_value),        \
                },                                                      \
                .string = (_string),                                    \
-       },
+       }),
 
-static const struct lttng_enum_entry dt_enum[_NR_LTTNG_UST_DYNAMIC_TYPES] = {
+static const struct lttng_ust_enum_entry *dt_enum[_NR_LTTNG_UST_DYNAMIC_TYPES] = {
        [LTTNG_UST_DYNAMIC_TYPE_NONE] = ctf_enum_value("_none", 0)
        [LTTNG_UST_DYNAMIC_TYPE_S8] = ctf_enum_value("_int8", 1)
        [LTTNG_UST_DYNAMIC_TYPE_S16] = ctf_enum_value("_int16", 2)
@@ -45,7 +46,7 @@ static const struct lttng_enum_entry dt_enum[_NR_LTTNG_UST_DYNAMIC_TYPES] = {
        [LTTNG_UST_DYNAMIC_TYPE_STRING] = ctf_enum_value("_string", 11)
 };
 
-static const struct lttng_enum_desc dt_enum_desc = {
+static const struct lttng_ust_enum_desc dt_enum_desc = {
        .name = "dynamic_type_enum",
        .entries = dt_enum,
        .nr_entries = LTTNG_ARRAY_SIZE(dt_enum),

diff --git a/liblttng-ust/ust-core.c b/liblttng-ust/ust-core.c
index 17fa7d1e7cb1f813f03c0f76efa46a0b3cf067c1..0b52f298ee2a9c16cf38d8d2d68eefe39f425618 100644 (file)
--- a/liblttng-ust/ust-core.c
+++ b/liblttng-ust/ust-core.c
@@ -87,7 +87,7 @@ void lttng_counter_transport_unregister(struct lttng_counter_transport *transpor
  * Needed by comm layer.
  */
 struct lttng_enum *lttng_ust_enum_get_from_desc(struct lttng_session *session,
-               const struct lttng_enum_desc *enum_desc)
+               const struct lttng_ust_enum_desc *enum_desc)
 {
        struct lttng_enum *_enum;
        struct cds_hlist_head *head;

diff --git a/liblttng-ust/ust-events-internal.h b/liblttng-ust/ust-events-internal.h
index ac85b7116e2931fdfd6430a7403a814461fa43ce..f351e954767f0fe0e8c19a6f92fa82e15a507383 100644 (file)
--- a/liblttng-ust/ust-events-internal.h
+++ b/liblttng-ust/ust-events-internal.h
@@ -543,7 +543,7 @@ struct cds_list_head *lttng_get_probe_list_head(void);
 
 LTTNG_HIDDEN
 struct lttng_enum *lttng_ust_enum_get_from_desc(struct lttng_session *session,
-               const struct lttng_enum_desc *enum_desc);
+               const struct lttng_ust_enum_desc *enum_desc);
 
 LTTNG_HIDDEN
 int lttng_abi_create_root_handle(void);