[PATCH 2/5] perf tools: Allow to reset open files counter

[Jiri Olsa <jolsa@kernel.org>]

I hit a bug when running test suite without forking
each test (-F option):

  $ perf test -F dso
   8: Test dso data read                                       : Ok
   9: Test dso data cache                                      : FAILED!
  10: Test dso data reopen                                     : FAILED!

The reason the session file limit is set just once for
perf process so we need to reset it for each test,
otherwise wrong limit is taken into account.

Link: http://lkml.kernel.org/n/tip-bqapag0ljaiwmb7hlkw09zk5@git.kernel.org
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 tools/perf/tests/dso-data.c |  6 ++++++
 tools/perf/util/dso.c       | 22 ++++++++++++++++------
 tools/perf/util/dso.h       |  2 ++
 3 files changed, 24 insertions(+), 6 deletions(-)

diff --git a/tools/perf/tests/dso-data.c b/tools/perf/tests/dso-data.c
index 8cf0d9e189a8..13725e09ba22 100644
--- a/tools/perf/tests/dso-data.c
+++ b/tools/perf/tests/dso-data.c
@@ -251,6 +251,9 @@ int test__dso_data_cache(int subtest __maybe_unused)
 	long nr_end, nr = open_files_cnt();
 	int dso_cnt, limit, i, fd;
 
+	/* Rest the internal dso open counter limit. */
+	reset_fd_limit();
+
 	memset(&machine, 0, sizeof(machine));
 
 	/* set as system limit */
@@ -312,6 +315,9 @@ int test__dso_data_reopen(int subtest __maybe_unused)
 #define dso_1 (dsos[1])
 #define dso_2 (dsos[2])
 
+	/* Rest the internal dso open counter limit. */
+	reset_fd_limit();
+
 	memset(&machine, 0, sizeof(machine));
 
 	/*
diff --git a/tools/perf/util/dso.c b/tools/perf/util/dso.c
index 5d286f5d7906..e1de6cc4863e 100644
--- a/tools/perf/util/dso.c
+++ b/tools/perf/util/dso.c
@@ -442,17 +442,27 @@ static rlim_t get_fd_limit(void)
 	return limit;
 }
 
-static bool may_cache_fd(void)
+static rlim_t fd_limit;
+
+/*
+ * Used only by tests/dso-data.c to reset the environment
+ * for tests. I dont expect we should change this during
+ * standard runtime.
+ */
+void reset_fd_limit(void)
 {
-	static rlim_t limit;
+	fd_limit = 0;
+}
 
-	if (!limit)
-		limit = get_fd_limit();
+static bool may_cache_fd(void)
+{
+	if (!fd_limit)
+		fd_limit = get_fd_limit();
 
-	if (limit == RLIM_INFINITY)
+	if (fd_limit == RLIM_INFINITY)
 		return true;
 
-	return limit > (rlim_t) dso__data_open_cnt;
+	return fd_limit > (rlim_t) dso__data_open_cnt;
 }
 
 /*
diff --git a/tools/perf/util/dso.h b/tools/perf/util/dso.h
index 76d79d070e21..a571f24895ca 100644
--- a/tools/perf/util/dso.h
+++ b/tools/perf/util/dso.h
@@ -360,4 +360,6 @@ enum dso_type dso__type(struct dso *dso, struct machine *machine);
 
 int dso__strerror_load(struct dso *dso, char *buf, size_t buflen);
 
+void reset_fd_limit(void);
+
 #endif /* __PERF_DSO */
-- 
2.4.11