&top->session->host_machine);
        perf_top__start_counters(top);
        top->session->evlist = top->evlist;
-       perf_session__update_sample_type(top->session);
+       perf_session__set_id_hdr_size(top->session);
 
        /* Wait for a minimal set of events before starting the snapshot */
        poll(top->evlist->pollfd, top->evlist->nr_fds, 100);
 
        return -1;
 }
 
-void perf_session__update_sample_type(struct perf_session *self)
+void perf_session__set_id_hdr_size(struct perf_session *session)
 {
-       self->id_hdr_size = perf_evlist__id_hdr_size(self->evlist);
-       self->host_machine.id_hdr_size = self->id_hdr_size;
-       machines__set_id_hdr_size(&self->machines, self->id_hdr_size);
+       u16 id_hdr_size = perf_evlist__id_hdr_size(session->evlist);
+
+       session->host_machine.id_hdr_size = id_hdr_size;
+       machines__set_id_hdr_size(&session->machines, id_hdr_size);
 }
 
 int perf_session__create_kernel_maps(struct perf_session *self)
        if (mode == O_RDONLY) {
                if (perf_session__open(self, force) < 0)
                        goto out_delete;
-               perf_session__update_sample_type(self);
+               perf_session__set_id_hdr_size(self);
        } else if (mode == O_WRONLY) {
                /*
                 * In O_RDONLY mode this will be performed when reading the
        case PERF_RECORD_HEADER_ATTR:
                err = tool->attr(event, &session->evlist);
                if (err == 0)
-                       perf_session__update_sample_type(session);
+                       perf_session__set_id_hdr_size(session);
                return err;
        case PERF_RECORD_HEADER_EVENT_TYPE:
                return tool->event_type(tool, event);
 
        int                     fd;
        bool                    fd_pipe;
        bool                    repipe;
-       u16                     id_hdr_size;
        int                     cwdlen;
        char                    *cwd;
        struct ordered_samples  ordered_samples;
 
 int perf_session__create_kernel_maps(struct perf_session *self);
 
-void perf_session__update_sample_type(struct perf_session *self);
+void perf_session__set_id_hdr_size(struct perf_session *session);
 void perf_session__remove_thread(struct perf_session *self, struct thread *th);
 
 static inline