Implement capturing payload on event notifier

[lttng-modules.git] / src / lttng-ring-buffer-event-notifier-client.h

diff --git a/src/lttng-ring-buffer-event-notifier-client.h b/src/lttng-ring-buffer-event-notifier-client.h
index ea0ab66ed1fa868dd3d6701014bb9e081b18c8a3..a857c8f7ef6684eed968f7e3354344889c3c4fc4 100644 (file)
--- a/src/lttng-ring-buffer-event-notifier-client.h
+++ b/src/lttng-ring-buffer-event-notifier-client.h
@@ -7,9 +7,11 @@
  * Copyright (C) 2010-2020 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
  */
 
+#include <linux/limits.h>
 #include <linux/module.h>
 #include <linux/types.h>
 #include <wrapper/vmalloc.h>   /* for wrapper_vmalloc_sync_mappings() */
+#include <lttng/abi.h>
 #include <lttng/events.h>
 #include <lttng/tracer.h>
 
@@ -20,6 +22,7 @@ struct event_notifier_packet_header {
 };
 
 struct event_notifier_record_header {
+       uint32_t payload_len;           /* in bytes */
        uint8_t header_end[0];          /* End of header */
 };
 
@@ -38,7 +41,17 @@ size_t record_header_size(const struct lib_ring_buffer_config *config,
                                 struct lib_ring_buffer_ctx *ctx,
                                 void *client_ctx)
 {
-       return 0;
+       size_t orig_offset = offset;
+       size_t padding;
+
+       padding = lib_ring_buffer_align(offset, lttng_alignof(uint32_t));
+       offset += padding;
+
+       offset += sizeof(uint32_t);
+
+       *pre_header_padding = padding;
+
+       return offset - orig_offset;
 }
 
 #include <ringbuffer/api.h>
@@ -55,7 +68,8 @@ size_t client_record_header_size(const struct lib_ring_buffer_config *config,
                                 struct lib_ring_buffer_ctx *ctx,
                                 void *client_ctx)
 {
-       return 0;
+       return record_header_size(config, chan, offset,
+                                 pre_header_padding, ctx, client_ctx);
 }
 
 /**
@@ -169,10 +183,7 @@ static void client_record_get(const struct lib_ring_buffer_config *config,
                        offsetof(struct event_notifier_record_header, header_end));
        CHAN_WARN_ON(chan, ret != offsetof(struct event_notifier_record_header, header_end));
        *header_len = offsetof(struct event_notifier_record_header, header_end);
-       /*
-        * Currently, only 64-bit event notifier ID.
-        */
-       *payload_len = sizeof(uint64_t);
+       *payload_len = header.payload_len;
        *timestamp = 0;
 }
 
@@ -273,6 +284,21 @@ void lttng_buffer_read_close(struct lib_ring_buffer *buf)
        lib_ring_buffer_release_read(buf);
 }
 
+static
+void lttng_write_event_notifier_header(const struct lib_ring_buffer_config *config,
+                           struct lib_ring_buffer_ctx *ctx)
+{
+       uint32_t data_size;
+
+       WARN_ON_ONCE(ctx->data_size > U32_MAX);
+
+       data_size = (uint32_t) ctx->data_size;
+
+       lib_ring_buffer_write(config, ctx, &data_size, sizeof(data_size));
+
+       lib_ring_buffer_align_ctx(ctx, ctx->largest_align);
+}
+
 static
 int lttng_event_reserve(struct lib_ring_buffer_ctx *ctx, uint32_t event_id)
 {
@@ -283,6 +309,8 @@ int lttng_event_reserve(struct lib_ring_buffer_ctx *ctx, uint32_t event_id)
                return ret;
        lib_ring_buffer_backend_get_pages(&client_config, ctx,
                        &ctx->backend_pages);
+
+       lttng_write_event_notifier_header(&client_config, ctx);
        return 0;
 }