netdev - Re: [PATCH bpf-next] selftests/bpf: fix trampoline

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Date:   Fri, 21 Feb 2020 04:31:46 +0000
From:   Song Liu <songliubraving@...com>
To:     Andrii Nakryiko <andriin@...com>
CC:     Song Liu <song@...nel.org>, bpf <bpf@...r.kernel.org>,
        Networking <netdev@...r.kernel.org>,
        Alexei Starovoitov <ast@...com>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii.nakryiko@...il.com>,
        "Kernel Team" <Kernel-team@...com>, Jiri Olsa <jolsa@...nel.org>
Subject: Re: [PATCH bpf-next] selftests/bpf: fix trampoline_count clean up
 logic



> On Feb 20, 2020, at 8:20 PM, Andrii Nakryiko <andriin@...com> wrote:
> 
> On 2/20/20 6:06 PM, Song Liu wrote:
>> On Thu, Feb 20, 2020 at 3:07 PM Andrii Nakryiko <andriin@...com> wrote:
>>> 
>>> Libbpf's Travis CI tests caught this issue. Ensure bpf_link and bpf_object
>>> clean up is performed correctly.
>>> 
>>> Fixes: d633d57902a5 ("selftest/bpf: Add test for allowed trampolines count")
>>> Cc: Jiri Olsa <jolsa@...nel.org>
>>> Signed-off-by: Andrii Nakryiko <andriin@...com>
>>> ---
>>>  .../bpf/prog_tests/trampoline_count.c         | 25 +++++++++++++------
>>>  1 file changed, 18 insertions(+), 7 deletions(-)
>>> 
>>> diff --git a/tools/testing/selftests/bpf/prog_tests/trampoline_count.c b/tools/testing/selftests/bpf/prog_tests/trampoline_count.c
>>> index 1f6ccdaed1ac..781c8d11604b 100644
>>> --- a/tools/testing/selftests/bpf/prog_tests/trampoline_count.c
>>> +++ b/tools/testing/selftests/bpf/prog_tests/trampoline_count.c
>>> @@ -55,31 +55,40 @@ void test_trampoline_count(void)
>>>         /* attach 'allowed' 40 trampoline programs */
>>>         for (i = 0; i < MAX_TRAMP_PROGS; i++) {
>>>                 obj = bpf_object__open_file(object, NULL);
>>> -               if (CHECK(IS_ERR(obj), "obj_open_file", "err %ld\n", PTR_ERR(obj)))
>>> +               if (CHECK(IS_ERR(obj), "obj_open_file", "err %ld\n", PTR_ERR(obj))) {
>>> +                       obj = NULL;
>> I think we don't need obj and link in cleanup? Did I miss anything?
> 
> We do set obj below (line 87) after this loop, so need to clean it up as well. As for link, yeah, technically link doesn't have to be set to NULL, but I kind of did it for completeness without thinking too much.

I meant "obj = NULL;" before "goto cleanup;", as we don't use obj in the 
cleanup path. 

Anyway, this is not a real issue. 

Thanks,
Song