On Jun 26, 2020, at 1:21 PM, Andrii Nakryiko [off-list ref] wrote:

On Thu, Jun 25, 2020 at 5:15 PM Song Liu [off-list ref] wrote:

quoted

The new test is similar to other bpf_iter tests.

Signed-off-by: Song Liu <redacted>
---
.../selftests/bpf/prog_tests/bpf_iter.c       | 17 ++++++
.../selftests/bpf/progs/bpf_iter_task_stack.c | 60 +++++++++++++++++++
2 files changed, 77 insertions(+)
create mode 100644 tools/testing/selftests/bpf/progs/bpf_iter_task_stack.c

diff --git a/tools/testing/selftests/bpf/prog_tests/bpf_iter.c b/tools/testing/selftests/bpf/prog_tests/bpf_iter.c
index 87c29dde1cf96..baa83328f810d 100644
--- a/tools/testing/selftests/bpf/prog_tests/bpf_iter.c
+++ b/tools/testing/selftests/bpf/prog_tests/bpf_iter.c

@@ -5,6 +5,7 @@

#include "bpf_iter_netlink.skel.h"
#include "bpf_iter_bpf_map.skel.h"
#include "bpf_iter_task.skel.h"
+#include "bpf_iter_task_stack.skel.h"
#include "bpf_iter_task_file.skel.h"
#include "bpf_iter_test_kern1.skel.h"
#include "bpf_iter_test_kern2.skel.h"

@@ -106,6 +107,20 @@ static void test_task(void)
       bpf_iter_task__destroy(skel);

}

+static void test_task_stack(void)
+{
+       struct bpf_iter_task_stack *skel;
+
+       skel = bpf_iter_task_stack__open_and_load();
+       if (CHECK(!skel, "bpf_iter_task_stack__open_and_load",
+                 "skeleton open_and_load failed\n"))
+               return;
+
+       do_dummy_read(skel->progs.dump_task_stack);
+
+       bpf_iter_task_stack__destroy(skel);
+}
+
static void test_task_file(void)
{
       struct bpf_iter_task_file *skel;

@@ -392,6 +407,8 @@ void test_bpf_iter(void)
               test_bpf_map();
       if (test__start_subtest("task"))
               test_task();
+       if (test__start_subtest("task_stack"))
+               test_task_stack();
       if (test__start_subtest("task_file"))
               test_task_file();
       if (test__start_subtest("anon"))

diff --git a/tools/testing/selftests/bpf/progs/bpf_iter_task_stack.c b/tools/testing/selftests/bpf/progs/bpf_iter_task_stack.c
new file mode 100644
index 0000000000000..83aca5b1a7965
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/bpf_iter_task_stack.c

@@ -0,0 +1,60 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2020 Facebook */
+/* "undefine" structs in vmlinux.h, because we "override" them below */
+#define bpf_iter_meta bpf_iter_meta___not_used
+#define bpf_iter__task bpf_iter__task___not_used
+#include "vmlinux.h"
+#undef bpf_iter_meta
+#undef bpf_iter__task
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+char _license[] SEC("license") = "GPL";
+
+/* bpf_get_task_stack needs a stackmap to work */

no it doesn't anymore :) please drop

We still need stack_map_alloc() to call get_callchain_buffers() in this
case. Without an active stack map, get_callchain_buffers() may fail. 

Thanks,
Song