perf tools: Fix PMU object alias initialization

The pmu_lookup should return pmus that do not expose the 'events'
group attribute in sysfs. Also it should fail when any other error
during 'events' lookup is hit (pmu_aliases fails).
Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Stephane Eranian <eranian@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1349873598-12583-7-git-send-email-jolsa@redhat.comSigned-off-by: Ingo Molnar <mingo@kernel.org>

tools/perf/util/pmu.c

@@ -164,7 +164,7 @@ static int pmu_aliases(char *name, struct list_head *head)
 		 "%s/bus/event_source/devices/%s/events", sysfs, name);
 
 	if (stat(path, &st) < 0)
-		return -1;
+		return 0;	 /* no error if 'events' does not exist */
 
 	if (pmu_aliases_parse(path, head))
 		return -1;
@@ -296,6 +296,9 @@ static struct perf_pmu *pmu_lookup(char *name)
 	if (pmu_format(name, &format))
 		return NULL;
 
+	if (pmu_aliases(name, &aliases))
+		return NULL;
+
 	if (pmu_type(name, &type))
 		return NULL;
 
@@ -305,8 +308,6 @@ static struct perf_pmu *pmu_lookup(char *name)
 
 	pmu->cpus = pmu_cpumask(name);
 
-	pmu_aliases(name, &aliases);
-
 	INIT_LIST_HEAD(&pmu->format);
 	INIT_LIST_HEAD(&pmu->aliases);
 	list_splice(&format, &pmu->format);