Fix ABI: Adding missing padding in tracepoint event structures

Add padding for future extensions.

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

diff --git a/include/lttng/ust-events.h b/include/lttng/ust-events.h
index 2f00440bdc173dbced449363e252860c190cd178..2bf05d56af0b199a492541304badeb0e0d982306 100644 (file)
--- a/include/lttng/ust-events.h
+++ b/include/lttng/ust-events.h
@@ -31,6 +31,11 @@ struct ltt_channel;
 struct ltt_session;
 struct lttng_ust_lib_ring_buffer_ctx;
 
+/*
+ * Data structures used by tracepoint event declarations, and by the
+ * tracer. Those structures have padding for future extension.
+ */
+
 /*
  * LTTng client type enumeration. Used by the consumer to map the
  * callbacks from its own address space.
@@ -63,9 +68,11 @@ enum lttng_string_encodings {
        NR_STRING_ENCODINGS,
 };
 
+#define LTTNG_UST_ENUM_ENTRY_PADDING   16
 struct lttng_enum_entry {
        unsigned long long start, end;  /* start and end are inclusive */
        const char *string;
+       char padding[LTTNG_UST_ENUM_ENTRY_PADDING];
 };
 
 #define __type_integer(_type, _byte_order, _base, _encoding)   \
@@ -82,6 +89,7 @@ struct lttng_enum_entry {
                },                                              \
        }                                                       \
 
+#define LTTNG_UST_INTEGER_TYPE_PADDING 24
 struct lttng_integer_type {
        unsigned int size;              /* in bits */
        unsigned short alignment;       /* in bits */
@@ -89,6 +97,7 @@ struct lttng_integer_type {
        unsigned int reverse_byte_order:1;
        unsigned int base;              /* 2, 8, 10, 16, for pretty print */
        enum lttng_string_encodings encoding;
+       char padding[LTTNG_UST_INTEGER_TYPE_PADDING];
 };
 
 /*
@@ -113,13 +122,16 @@ struct lttng_integer_type {
                },                                              \
        }                                                       \
 
+#define LTTNG_UST_FLOAT_TYPE_PADDING   24
 struct lttng_float_type {
        unsigned int exp_dig;           /* exponent digits, in bits */
        unsigned int mant_dig;          /* mantissa digits, in bits */
        unsigned short alignment;       /* in bits */
        unsigned int reverse_byte_order:1;
+       char padding[LTTNG_UST_FLOAT_TYPE_PADDING];
 };
 
+#define LTTNG_UST_BASIC_TYPE_PADDING   128
 union _lttng_basic_type {
        struct lttng_integer_type integer;
        struct {
@@ -129,6 +141,7 @@ union _lttng_basic_type {
                enum lttng_string_encodings encoding;
        } string;
        struct lttng_float_type _float;
+       char padding[LTTNG_UST_BASIC_TYPE_PADDING];
 };
 
 struct lttng_basic_type {
@@ -138,6 +151,7 @@ struct lttng_basic_type {
        } u;
 };
 
+#define LTTNG_UST_TYPE_PADDING 128
 struct lttng_type {
        enum abstract_types atype;
        union {
@@ -150,23 +164,29 @@ struct lttng_type {
                        struct lttng_basic_type length_type;
                        struct lttng_basic_type elem_type;
                } sequence;
+               char padding[LTTNG_UST_TYPE_PADDING];
        } u;
 };
 
+#define LTTNG_UST_ENUM_TYPE_PADDING    24
 struct lttng_enum {
        const char *name;
        struct lttng_type container_type;
        const struct lttng_enum_entry *entries;
        unsigned int len;
+       char padding[LTTNG_UST_ENUM_TYPE_PADDING];
 };
 
 /* Event field description */
 
+#define LTTNG_UST_EVENT_FIELD_PADDING  32
 struct lttng_event_field {
        const char *name;
        struct lttng_type type;
+       char padding[LTTNG_UST_EVENT_FIELD_PADDING];
 };
 
+#define LTTNG_UST_CTX_FIELD_PADDING    40
 struct lttng_ctx_field {
        struct lttng_event_field event_field;
        size_t (*get_size)(size_t offset);
@@ -174,16 +194,41 @@ struct lttng_ctx_field {
                       struct lttng_ust_lib_ring_buffer_ctx *ctx,
                       struct ltt_channel *chan);
        union {
+               char padding[LTTNG_UST_CTX_FIELD_PADDING];
        } u;
        void (*destroy)(struct lttng_ctx_field *field);
 };
 
+#define LTTNG_UST_CTX_PADDING  24
 struct lttng_ctx {
        struct lttng_ctx_field *fields;
        unsigned int nr_fields;
        unsigned int allocated_fields;
+       char padding[LTTNG_UST_CTX_PADDING];
+};
+
+#define LTTNG_UST_EVENT_DESC_PADDING   40
+struct lttng_event_desc {
+       const char *name;
+       void *probe_callback;
+       const struct lttng_event_ctx *ctx;      /* context */
+       const struct lttng_event_field *fields; /* event payload */
+       unsigned int nr_fields;
+       const int **loglevel;
+       char padding[LTTNG_UST_EVENT_DESC_PADDING];
+};
+
+#define LTTNG_UST_PROBE_DESC_PADDING   40
+struct lttng_probe_desc {
+       const char *provider;
+       const struct lttng_event_desc **event_desc;
+       unsigned int nr_events;
+       struct cds_list_head head;              /* chain registered probes */
+       char padding[LTTNG_UST_PROBE_DESC_PADDING];
 };
 
+/* Data structures used by the tracer. */
+
 /*
  * Entry describing a per-session active wildcard, along with the event
  * attribute and channel information configuring the events that need to
@@ -213,22 +258,6 @@ struct wildcard_entry {
        char name[0];
 };
 
-struct lttng_event_desc {
-       const char *name;
-       void *probe_callback;
-       const struct lttng_event_ctx *ctx;      /* context */
-       const struct lttng_event_field *fields; /* event payload */
-       unsigned int nr_fields;
-       const int **loglevel;
-};
-
-struct lttng_probe_desc {
-       const char *provider;
-       const struct lttng_event_desc **event_desc;
-       unsigned int nr_events;
-       struct cds_list_head head;              /* chain registered probes */
-};
-
 struct tp_list_entry {
        struct lttng_ust_tracepoint_iter tp;
        struct cds_list_head head;