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

[lttng-ust.git] / libringbuffer / frontend_types.h

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