linux-kernel - [PATCH 3.16 035/217] perf tools: Dont stop PMU parsing on alias parse error

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Message-ID: <lsq.1461711741.652607314@decadent.org.uk>
Date:	Wed, 27 Apr 2016 01:02:21 +0200
From:	Ben Hutchings <ben@...adent.org.uk>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:	akpm@...ux-foundation.org, "Jiri Olsa" <jolsa@...nel.org>,
	"Arnaldo Carvalho de Melo" <acme@...hat.com>,
	"Andi Kleen" <ak@...ux.intel.com>
Subject: [PATCH 3.16 035/217] perf tools: Dont stop PMU parsing on alias
 parse error

3.16.35-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Andi Kleen <ak@...ux.intel.com>

commit 940db6dcd3f4659303fdf6befe7416adc4d24118 upstream.

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@...ux.intel.com>
Cc: Jiri Olsa <jolsa@...nel.org>
Link: http://lkml.kernel.org/r/1455749095-18358-1-git-send-email-andi@firstfloor.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 tools/perf/util/pmu.c | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

--- a/tools/perf/util/pmu.c
+++ b/tools/perf/util/pmu.c
@@ -217,13 +217,12 @@ static int pmu_aliases_parse(char *dir,
 	struct dirent *evt_ent;
 	DIR *event_dir;
 	size_t len;
-	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;
@@ -243,17 +242,19 @@ static int pmu_aliases_parse(char *dir,
 
 		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;
 }
 
 /*