From 68816f8a1a5274ca16a0ebe27882dd6e95076762 Mon Sep 17 00:00:00 2001
From: Arnaldo Carvalho de Melo <acme@redhat.com>
Date: Sat, 21 Nov 2009 14:31:26 -0200
Subject: [PATCH] --- yaml --- r: 169729 b: refs/heads/master c:
 e25613683bd5c46d3e8c8ae6416dccc9f357dcdc h: refs/heads/master i:   169727:
 bee6342f96705e69683fca04ab71f30f4b2d8542 v: v3

---
 [refs]                                   |  2 +-
 trunk/tools/perf/util/trace-event-info.c | 22 +++++++++++++++-------
 trunk/tools/perf/util/trace-event-read.c |  4 ++--
 trunk/tools/perf/util/trace-event.h      |  2 +-
 4 files changed, 19 insertions(+), 11 deletions(-)

diff --git a/[refs] b/[refs]
index 48cafe9e61df..5abc0fc60a00 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: c12e15e71d4b32da045e798ffd21cbb6197d1c65
+refs/heads/master: e25613683bd5c46d3e8c8ae6416dccc9f357dcdc
diff --git a/trunk/tools/perf/util/trace-event-info.c b/trunk/tools/perf/util/trace-event-info.c
index 831052d4b4fb..cace35595530 100644
--- a/trunk/tools/perf/util/trace-event-info.c
+++ b/trunk/tools/perf/util/trace-event-info.c
@@ -33,11 +33,11 @@
 #include <ctype.h>
 #include <errno.h>
 #include <stdbool.h>
+#include <linux/kernel.h>
 
 #include "../perf.h"
 #include "trace-event.h"
 
-
 #define VERSION "0.5"
 
 #define _STR(x) #x
@@ -483,23 +483,31 @@ static struct tracepoint_path *
 get_tracepoints_path(struct perf_event_attr *pattrs, int nb_events)
 {
 	struct tracepoint_path path, *ppath = &path;
-	int i;
+	int i, nr_tracepoints = 0;
 
 	for (i = 0; i < nb_events; i++) {
 		if (pattrs[i].type != PERF_TYPE_TRACEPOINT)
 			continue;
+		++nr_tracepoints;
 		ppath->next = tracepoint_id_to_path(pattrs[i].config);
 		if (!ppath->next)
 			die("%s\n", "No memory to alloc tracepoints list");
 		ppath = ppath->next;
 	}
 
-	return path.next;
+	return nr_tracepoints > 0 ? path.next : NULL;
 }
-void read_tracing_data(int fd, struct perf_event_attr *pattrs, int nb_events)
+
+int read_tracing_data(int fd, struct perf_event_attr *pattrs, int nb_events)
 {
 	char buf[BUFSIZ];
-	struct tracepoint_path *tps;
+	struct tracepoint_path *tps = get_tracepoints_path(pattrs, nb_events);
+
+	/*
+	 * What? No tracepoints? No sense writing anything here, bail out.
+	 */
+	if (tps == NULL)
+		return -1;
 
 	output_fd = fd;
 
@@ -528,11 +536,11 @@ void read_tracing_data(int fd, struct perf_event_attr *pattrs, int nb_events)
 	page_size = getpagesize();
 	write_or_die(&page_size, 4);
 
-	tps = get_tracepoints_path(pattrs, nb_events);
-
 	read_header_files();
 	read_ftrace_files(tps);
 	read_event_files(tps);
 	read_proc_kallsyms();
 	read_ftrace_printk();
+
+	return 0;
 }
diff --git a/trunk/tools/perf/util/trace-event-read.c b/trunk/tools/perf/util/trace-event-read.c
index 44292e06cca4..342dfdd43f87 100644
--- a/trunk/tools/perf/util/trace-event-read.c
+++ b/trunk/tools/perf/util/trace-event-read.c
@@ -471,11 +471,11 @@ void trace_report(int fd)
 
 	read_or_die(buf, 3);
 	if (memcmp(buf, test, 3) != 0)
-		die("not an trace data file");
+		die("no trace data in the file");
 
 	read_or_die(buf, 7);
 	if (memcmp(buf, "tracing", 7) != 0)
-		die("not a trace file (missing tracing)");
+		die("not a trace file (missing 'tracing' tag)");
 
 	version = read_string();
 	if (show_version)
diff --git a/trunk/tools/perf/util/trace-event.h b/trunk/tools/perf/util/trace-event.h
index f6637c2fa1fe..dd51c6872a15 100644
--- a/trunk/tools/perf/util/trace-event.h
+++ b/trunk/tools/perf/util/trace-event.h
@@ -248,7 +248,7 @@ unsigned long long
 raw_field_value(struct event *event, const char *name, void *data);
 void *raw_field_ptr(struct event *event, const char *name, void *data);
 
-void read_tracing_data(int fd, struct perf_event_attr *pattrs, int nb_events);
+int read_tracing_data(int fd, struct perf_event_attr *pattrs, int nb_events);
 
 /* taken from kernel/trace/trace.h */
 enum trace_flag_type {