[PATCH] perf tests: Fix false TEST_OK result for 'perf test hist'

[Wang Nan <wangnan0@huawei.com>]

Commit 71d6de64feddd4b455555326fba2111b3006d9e0 ('perf test: Fix hist
testcases when kptr_restrict is on') solves a double free problem when
'perf test hist' calling setup_fake_machine(). However, the result is
still incorrect. For example:

 $ ./perf test -v 'filtering hist entries'
 25: Test filtering hist entries                              :
 --- start ---
 test child forked, pid 4186
 Cannot create kernel maps
 test child finished with 0
 ---- end ----
 Test filtering hist entries: Ok

In this case the body of this test is not get executed at all, but the
result is 'Ok'. I think 'Skip' should be better.

The reason is that *ALL* hists test cases forget to reset err after
using it to hold an error code.

This patch ensure err is reset.

In case when kptr_restrict prevent normal user get kernel address, this
test should be skipped, not fail. This patch uses linux/err.h to store
error code in return value of setup_fake_machine(), and let 'EACCES' to
indicate this problem.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Namhyung Kim <namhyung@kernel.org>
---
 tools/perf/tests/hists_common.c   | 12 +++++++++---
 tools/perf/tests/hists_common.h   |  1 +
 tools/perf/tests/hists_cumulate.c |  6 +++++-
 tools/perf/tests/hists_filter.c   |  6 +++++-
 tools/perf/tests/hists_link.c     |  6 +++++-
 tools/perf/tests/hists_output.c   |  6 +++++-
 6 files changed, 30 insertions(+), 7 deletions(-)

diff --git a/tools/perf/tests/hists_common.c b/tools/perf/tests/hists_common.c
index bcfd081..2eca1b2 100644
--- a/tools/perf/tests/hists_common.c
+++ b/tools/perf/tests/hists_common.c
@@ -81,15 +81,20 @@ struct machine *setup_fake_machine(struct machines *machines)
 {
 	struct machine *machine = machines__find(machines, HOST_KERNEL_ID);
 	size_t i;
+	int err = -ENOMEM;
 
 	if (machine == NULL) {
 		pr_debug("Not enough memory for machine setup\n");
-		return NULL;
+		return ERR_PTR(-ENOMEM);
 	}
 
 	if (machine__create_kernel_maps(machine)) {
 		pr_debug("Cannot create kernel maps\n");
-		return NULL;
+		if (symbol_conf.kptr_restrict) {
+			pr_debug("Hint: Check /proc/sys/kernel/kptr_restrict.\n");
+			err = -EACCES;
+		}
+		return ERR_PTR(err);
 	}
 
 	for (i = 0; i < ARRAY_SIZE(fake_threads); i++) {
@@ -155,7 +160,8 @@ struct machine *setup_fake_machine(struct machines *machines)
 out:
 	pr_debug("Not enough memory for machine setup\n");
 	machine__delete_threads(machine);
-	return NULL;
+	machine__exit(machine);
+	return ERR_PTR(err);
 }
 
 void print_hists_in(struct hists *hists)
diff --git a/tools/perf/tests/hists_common.h b/tools/perf/tests/hists_common.h
index 888254e..0252eae 100644
--- a/tools/perf/tests/hists_common.h
+++ b/tools/perf/tests/hists_common.h
@@ -1,5 +1,6 @@
 #ifndef __PERF_TESTS__HISTS_COMMON_H__
 #define __PERF_TESTS__HISTS_COMMON_H__
+#include <linux/err.h>
 
 struct machine;
 struct machines;
diff --git a/tools/perf/tests/hists_cumulate.c b/tools/perf/tests/hists_cumulate.c
index 8292948..c211075 100644
--- a/tools/perf/tests/hists_cumulate.c
+++ b/tools/perf/tests/hists_cumulate.c
@@ -706,13 +706,17 @@ int test__hists_cumulate(int subtest __maybe_unused)
 	err = parse_events(evlist, "cpu-clock", NULL);
 	if (err)
 		goto out;
+	err = TEST_FAIL;
 
 	machines__init(&machines);
 
 	/* setup threads/dso/map/symbols also */
 	machine = setup_fake_machine(&machines);
-	if (!machine)
+	if (IS_ERR(machine)) {
+		if (PTR_ERR(machine) == -EACCES)
+			err = TEST_SKIP;
 		goto out;
+	}
 
 	if (verbose > 1)
 		machine__fprintf(machine, stderr);
diff --git a/tools/perf/tests/hists_filter.c b/tools/perf/tests/hists_filter.c
index ccb5b49..795a04d 100644
--- a/tools/perf/tests/hists_filter.c
+++ b/tools/perf/tests/hists_filter.c
@@ -120,6 +120,7 @@ int test__hists_filter(int subtest __maybe_unused)
 	err = parse_events(evlist, "task-clock", NULL);
 	if (err)
 		goto out;
+	err = TEST_FAIL;
 
 	/* default sort order (comm,dso,sym) will be used */
 	if (setup_sorting() < 0)
@@ -129,8 +130,11 @@ int test__hists_filter(int subtest __maybe_unused)
 
 	/* setup threads/dso/map/symbols also */
 	machine = setup_fake_machine(&machines);
-	if (!machine)
+	if (IS_ERR(machine)) {
+		if (PTR_ERR(machine) == -EACCES)
+			err = TEST_SKIP;
 		goto out;
+	}
 
 	if (verbose > 1)
 		machine__fprintf(machine, stderr);
diff --git a/tools/perf/tests/hists_link.c b/tools/perf/tests/hists_link.c
index 6243e2b..f5f37ef9 100644
--- a/tools/perf/tests/hists_link.c
+++ b/tools/perf/tests/hists_link.c
@@ -293,6 +293,7 @@ int test__hists_link(int subtest __maybe_unused)
 	if (err)
 		goto out;
 
+	err = TEST_FAIL;
 	/* default sort order (comm,dso,sym) will be used */
 	if (setup_sorting() < 0)
 		goto out;
@@ -301,8 +302,11 @@ int test__hists_link(int subtest __maybe_unused)
 
 	/* setup threads/dso/map/symbols also */
 	machine = setup_fake_machine(&machines);
-	if (!machine)
+	if (IS_ERR(machine)) {
+		if (PTR_ERR(machine) == -EACCES)
+			err = TEST_SKIP;
 		goto out;
+	}
 
 	if (verbose > 1)
 		machine__fprintf(machine, stderr);
diff --git a/tools/perf/tests/hists_output.c b/tools/perf/tests/hists_output.c
index 248beec..cc570cf 100644
--- a/tools/perf/tests/hists_output.c
+++ b/tools/perf/tests/hists_output.c
@@ -597,13 +597,17 @@ int test__hists_output(int subtest __maybe_unused)
 	err = parse_events(evlist, "cpu-clock", NULL);
 	if (err)
 		goto out;
+	err = TEST_FAIL;
 
 	machines__init(&machines);
 
 	/* setup threads/dso/map/symbols also */
 	machine = setup_fake_machine(&machines);
-	if (!machine)
+	if (IS_ERR(machine)) {
+		if (PTR_ERR(machine) == -EACCES)
+			err = TEST_SKIP;
 		goto out;
+	}
 
 	if (verbose > 1)
 		machine__fprintf(machine, stderr);
-- 
1.8.3.4