[tip:perf/core] perf tools: Dont stop PMU parsing on alias parse error

[tip-bot for Andi Kleen]

Commit-ID:  940db6dcd3f4659303fdf6befe7416adc4d24118
Gitweb:     http://git.kernel.org/tip/940db6dcd3f4659303fdf6befe7416adc4d24118
Author:     Andi Kleen <ak@xxxxxxxxxxxxxxx>
AuthorDate: Wed, 17 Feb 2016 14:44:55 -0800
Committer:  Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
CommitDate: Tue, 23 Feb 2016 12:46:16 -0300

perf tools: Dont stop PMU parsing on alias parse error

When an error happens during alias parsing currently the complete
parsing of all attributes of the PMU is stopped. This is breaks old perf
on a newer kernel that may have not-yet-know alias attributes (such as
.scale or .per-pkg).

Continue when some attribute is unparseable.

This is IMHO a stable candidate and should be backported to older
versions to avoid problems with newer kernels.

v2: Print warnings when something goes wrong.
v3: Change warning to debug output

Signed-off-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx # v3.6+
Link: http://lkml.kernel.org/r/1455749095-18358-1-git-send-email-andi@xxxxxxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
 tools/perf/util/pmu.c | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
index cf59fba..ce61f79 100644
--- a/tools/perf/util/pmu.c
+++ b/tools/perf/util/pmu.c
@@ -284,13 +284,12 @@ static int pmu_aliases_parse(char *dir, struct list_head *head)
 {
 	struct dirent *evt_ent;
 	DIR *event_dir;
-	int ret = 0;
 
 	event_dir = opendir(dir);
 	if (!event_dir)
 		return -EINVAL;
 
-	while (!ret && (evt_ent = readdir(event_dir))) {
+	while ((evt_ent = readdir(event_dir))) {
 		char path[PATH_MAX];
 		char *name = evt_ent->d_name;
 		FILE *file;
@@ -306,17 +305,19 @@ static int pmu_aliases_parse(char *dir, struct list_head *head)
 
 		snprintf(path, PATH_MAX, "%s/%s", dir, name);
 
-		ret = -EINVAL;
 		file = fopen(path, "r");
-		if (!file)
-			break;
+		if (!file) {
+			pr_debug("Cannot open %s\n", path);
+			continue;
+		}
 
-		ret = perf_pmu__new_alias(head, dir, name, file);
+		if (perf_pmu__new_alias(head, dir, name, file) < 0)
+			pr_debug("Cannot set up %s\n", name);
 		fclose(file);
 	}
 
 	closedir(event_dir);
-	return ret;
+	return 0;
 }
 
 /*