> On Jun 26, 2020, at 4:11 PM, Andrii Nakryiko <andrii.nakryiko@xxxxxxxxx> wrote:
>
> On Fri, Jun 26, 2020 at 4:05 PM Song Liu <songliubraving@xxxxxx> wrote:
>>
>>
>>
>>> On Jun 26, 2020, at 1:21 PM, Andrii Nakryiko <andrii.nakryiko@xxxxxxxxx> wrote:
>>>
>>> On Thu, Jun 25, 2020 at 5:15 PM Song Liu <songliubraving@xxxxxx> wrote:
>>>>
>>>> The new test is similar to other bpf_iter tests.
>>>>
>>>> Signed-off-by: Song Liu <songliubraving@xxxxxx>
>>>> ---
>>>> .../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.
>
> Oh... um... is it possible to do it some other way? It's extremely
> confusing dependency. Does bpf_get_stack() also require stackmap?
>
Aha, I thought bpf_get_stack() also requires stackmap, but it doesn't.
The fix is in check_helper_call(). Let me do the same for bpf_get_task_stack().
Thanks,
Song
