perf session: Use perf_evlist__id_hdr_size more extensively

Removing perf_session->id_hdr_size, as it can be obtained from the
evsel/evlist.

Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-1nwc2kslu7gsfblu98xbqbll@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/builtin-record.c

@@ -313,7 +313,7 @@ static void perf_record__open(struct perf_record *rec)
 		}
  	}
 
-	perf_session__update_sample_type(session);
+	perf_session__set_id_hdr_size(session);
 }
 
 static int process_buildids(struct perf_record *rec)

tools/perf/builtin-top.c

@@ -1032,7 +1032,7 @@ static int __cmd_top(struct perf_top *top)
 					       &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);

tools/perf/util/session.c

@@ -101,11 +101,12 @@ static int perf_session__open(struct perf_session *self, bool force)
 	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)
@@ -165,7 +166,7 @@ struct perf_session *perf_session__new(const char *filename, int mode,
 	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
@@ -1054,7 +1055,7 @@ static int perf_session__process_user_event(struct perf_session *session, union
 	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);

tools/perf/util/session.h

@@ -44,7 +44,6 @@ struct perf_session {
 	int			fd;
 	bool			fd_pipe;
 	bool			repipe;
-	u16			id_hdr_size;
 	int			cwdlen;
 	char			*cwd;
 	struct ordered_samples	ordered_samples;
@@ -83,7 +82,7 @@ void perf_event__attr_swap(struct perf_event_attr *attr);
 
 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