Fix ABI: add padding to structures shared between UST and consumer

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

diff --git a/libringbuffer/backend_types.h b/libringbuffer/backend_types.h
index 3d8bd3cb3392c1f5c3db2d3fc11323e1b29f7081..81e67119847a119b2ad140e71aefa0a648ef5bfa 100644 (file)
--- a/libringbuffer/backend_types.h
+++ b/libringbuffer/backend_types.h
@@ -15,12 +15,14 @@
 #include "shm_internal.h"
 #include "vatomic.h"
 
+#define RB_BACKEND_PAGES_PADDING       16
 struct lttng_ust_lib_ring_buffer_backend_pages {
        unsigned long mmap_offset;      /* offset of the subbuffer in mmap */
        union v_atomic records_commit;  /* current records committed count */
        union v_atomic records_unread;  /* records to read */
        unsigned long data_size;        /* Amount of data to read from subbuf */
        DECLARE_SHMP(char, p);          /* Backing memory map */
+       char padding[RB_BACKEND_PAGES_PADDING];
 };
 
 struct lttng_ust_lib_ring_buffer_backend_subbuffer {
@@ -38,6 +40,7 @@ struct lttng_ust_lib_ring_buffer_backend_pages_shmp {
        DECLARE_SHMP(struct lttng_ust_lib_ring_buffer_backend_pages, shmp);
 };
 
+#define RB_BACKEND_RING_BUFFER_PADDING         64
 struct lttng_ust_lib_ring_buffer_backend {
        /* Array of ring_buffer_backend_subbuffer for writer */
        DECLARE_SHMP(struct lttng_ust_lib_ring_buffer_backend_subbuffer, buf_wsb);
@@ -54,12 +57,14 @@ struct lttng_ust_lib_ring_buffer_backend {
        int cpu;                        /* This buffer's cpu. -1 if global. */
        union v_atomic records_read;    /* Number of records read */
        unsigned int allocated:1;       /* is buffer allocated ? */
+       char padding[RB_BACKEND_RING_BUFFER_PADDING];
 };
 
 struct lttng_ust_lib_ring_buffer_shmp {
        DECLARE_SHMP(struct lttng_ust_lib_ring_buffer, shmp); /* Channel per-cpu buffers */
 };
 
+#define RB_BACKEND_CHANNEL_PADDING     64
 struct channel_backend {
        unsigned long buf_size;         /* Size of the buffer */
        unsigned long subbuf_size;      /* Sub-buffer size */
@@ -75,6 +80,7 @@ struct channel_backend {
        DECLARE_SHMP(void *, priv_data);/* Client-specific information */
        struct lttng_ust_lib_ring_buffer_config config; /* Ring buffer configuration */
        char name[NAME_MAX];            /* Channel name */
+       char padding[RB_BACKEND_CHANNEL_PADDING];
        struct lttng_ust_lib_ring_buffer_shmp buf[];
 };
 

diff --git a/libringbuffer/frontend_types.h b/libringbuffer/frontend_types.h
index 961c90e5084bd705c502d40e40a7cbb7b54307f6..1d47b275b6fabd3cdc2c5351771662b4989378f7 100644 (file)
--- a/libringbuffer/frontend_types.h
+++ b/libringbuffer/frontend_types.h
@@ -34,6 +34,7 @@
 enum switch_mode { SWITCH_ACTIVE, SWITCH_FLUSH };
 
 /* channel: collection of per-cpu ring buffers. */
+#define RB_CHANNEL_PADDING     64
 struct channel {
        int record_disabled;
        unsigned long commit_count_mask;        /*
@@ -53,20 +54,26 @@ struct channel {
         * be last member.
         */
        struct channel_backend backend;         /* Associated backend */
+       char padding[RB_CHANNEL_PADDING];
 } __attribute__((aligned(CAA_CACHE_LINE_SIZE)));
 
 /* Per-subbuffer commit counters used on the hot path */
+#define RB_COMMIT_COUNT_HOT_PADDING    16
 struct commit_counters_hot {
        union v_atomic cc;              /* Commit counter */
        union v_atomic seq;             /* Consecutive commits */
+       char padding[RB_COMMIT_COUNT_HOT_PADDING];
 } __attribute__((aligned(CAA_CACHE_LINE_SIZE)));
 
 /* Per-subbuffer commit counters used only on cold paths */
+#define RB_COMMIT_COUNT_COLD_PADDING   24
 struct commit_counters_cold {
        union v_atomic cc_sb;           /* Incremented _once_ at sb switch */
+       char padding[RB_COMMIT_COUNT_COLD_PADDING];
 } __attribute__((aligned(CAA_CACHE_LINE_SIZE)));
 
 /* ring buffer state */
+#define RB_RING_BUFFER_PADDING         64
 struct lttng_ust_lib_ring_buffer {
        /* First 32 bytes cache-hot cacheline */
        union v_atomic offset;          /* Current offset in the buffer */
@@ -109,6 +116,7 @@ struct lttng_ust_lib_ring_buffer {
                read_timer_enabled:1;   /* Protected by ring_buffer_nohz_lock */
        /* shmp pointer to self */
        DECLARE_SHMP(struct lttng_ust_lib_ring_buffer, self);
+       char padding[RB_RING_BUFFER_PADDING];
 } __attribute__((aligned(CAA_CACHE_LINE_SIZE)));
 
 static inline