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References: <20211212051816.20478-1-linmq006@gmail.com> <CAH-r-ZGri414YWumUs7U_ktvcv+BWOYfPTsB7So6kz5PNcK5tw@mail.gmail.com>
In-Reply-To: <CAH-r-ZGri414YWumUs7U_ktvcv+BWOYfPTsB7So6kz5PNcK5tw@mail.gmail.com>
From:   Andrii Nakryiko <andrii.nakryiko@gmail.com>
Date:   Mon, 13 Dec 2021 11:33:00 -0800
Message-ID: <CAEf4BzZG7_ihS7m8e9KNcoO0WhFXqw4iK1=SNPr2u3bPmOmxLQ@mail.gmail.com>
Subject: Re: [PATCH] bpftool: Fix NULL vs IS_ERR() checking for return value
 of hashmap__new
To:     =?UTF-8?B?5p6X5aaZ5YCp?= <linmq006@gmail.com>
Cc:     Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Andrii Nakryiko <andrii@kernel.org>,
        Martin KaFai Lau <kafai@fb.com>,
        Song Liu <songliubraving@fb.com>, Yonghong Song <yhs@fb.com>,
        John Fastabend <john.fastabend@gmail.com>,
        KP Singh <kpsingh@kernel.org>,
        Quentin Monnet <quentin@isovalent.com>,
        Networking <netdev@vger.kernel.org>, bpf <bpf@vger.kernel.org>,
        open list <linux-kernel@vger.kernel.org>
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On Mon, Dec 13, 2021 at 7:07 AM =E6=9E=97=E5=A6=99=E5=80=A9 <linmq006@gmail=
.com> wrote:
>
> Sorry, I forgot to do compile testing. I will test it and let you know.
>
> Miaoqian Lin <linmq006@gmail.com> =E4=BA=8E2021=E5=B9=B412=E6=9C=8812=E6=
=97=A5=E5=91=A8=E6=97=A5 13:18=E5=86=99=E9=81=93=EF=BC=9A
>>
>> The hashmap__new() function does not return NULL on errors. It returns
>> ERR_PTR(-ENOMEM). Using IS_ERR() to check the return value to fix this.
>>
>> Signed-off-by: Miaoqian Lin <linmq006@gmail.com>
>> ---

Please do test (not just compile test) and re-send all three patches
as one patch set instead of three independent patches. Thanks.


>>  tools/bpf/bpftool/link.c | 2 +-
>>  tools/bpf/bpftool/map.c  | 2 +-
>>  tools/bpf/bpftool/pids.c | 2 +-
>>  3 files changed, 3 insertions(+), 3 deletions(-)
>>
>> diff --git a/tools/bpf/bpftool/link.c b/tools/bpf/bpftool/link.c
>> index 2c258db0d352..0dc402a89cd8 100644
>> --- a/tools/bpf/bpftool/link.c
>> +++ b/tools/bpf/bpftool/link.c
>> @@ -306,7 +306,7 @@ static int do_show(int argc, char **argv)
>>         if (show_pinned) {
>>                 link_table =3D hashmap__new(hash_fn_for_key_as_id,
>>                                           equal_fn_for_key_as_id, NULL);
>> -               if (!link_table) {
>> +               if (IS_ERR(link_table)) {
>>                         p_err("failed to create hashmap for pinned paths=
");
>>                         return -1;
>>                 }
>> diff --git a/tools/bpf/bpftool/map.c b/tools/bpf/bpftool/map.c
>> index cae1f1119296..af83ae37d247 100644
>> --- a/tools/bpf/bpftool/map.c
>> +++ b/tools/bpf/bpftool/map.c
>> @@ -698,7 +698,7 @@ static int do_show(int argc, char **argv)
>>         if (show_pinned) {
>>                 map_table =3D hashmap__new(hash_fn_for_key_as_id,
>>                                          equal_fn_for_key_as_id, NULL);
>> -               if (!map_table) {
>> +               if (IS_ERR(map_table)) {
>>                         p_err("failed to create hashmap for pinned paths=
");
>>                         return -1;
>>                 }
>> diff --git a/tools/bpf/bpftool/pids.c b/tools/bpf/bpftool/pids.c
>> index 56b598eee043..6c4767e97061 100644
>> --- a/tools/bpf/bpftool/pids.c
>> +++ b/tools/bpf/bpftool/pids.c
>> @@ -101,7 +101,7 @@ int build_obj_refs_table(struct hashmap **map, enum =
bpf_obj_type type)
>>         libbpf_print_fn_t default_print;
>>
>>         *map =3D hashmap__new(hash_fn_for_key_as_id, equal_fn_for_key_as=
_id, NULL);
>> -       if (!*map) {
>> +       if (IS_ERR(*map)) {
>>                 p_err("failed to create hashmap for PID references");
>>                 return -1;
>>         }
>> --
>> 2.17.1
>>