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Date:   Mon, 5 Jun 2023 17:16:03 -0500
From:   David Vernet <void@manifault.com>
To:     Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc:     bpf <bpf@vger.kernel.org>, Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Andrii Nakryiko <andrii@kernel.org>,
        Martin KaFai Lau <martin.lau@linux.dev>,
        Song Liu <song@kernel.org>, Yonghong Song <yhs@fb.com>,
        John Fastabend <john.fastabend@gmail.com>,
        KP Singh <kpsingh@kernel.org>,
        Stanislav Fomichev <sdf@google.com>,
        Hao Luo <haoluo@google.com>, Jiri Olsa <jolsa@kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Kernel Team <kernel-team@meta.com>,
        Dave Marchevsky <davemarchevsky@meta.com>
Subject: Re: [PATCH bpf-next 2/2] selftests/bpf: Test bpf_for_each_map_elem
 on BPF_MAP_TYPE_HASH_OF_MAPS
Message-ID: <20230605221603.GB1892218@maniforge>
References: <20230605200508.1888874-1-void@manifault.com>
 <20230605200508.1888874-2-void@manifault.com>
 <CAADnVQLZkUFtCwZEaRKMrdnDJzj-9_7fMYY9P55MndiNTrSnkA@mail.gmail.com>
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On Mon, Jun 05, 2023 at 03:07:21PM -0700, Alexei Starovoitov wrote:
> On Mon, Jun 5, 2023 at 1:05 PM David Vernet <void@manifault.com> wrote:
> >
> > +
> > +static __u64 set_invoked(struct bpf_map *map, __u64 *key, __u64 *val, struct callback_ctx *ctx)
> > +{
> > +       struct bpf_map *inner_map;
> > +
> > +       ctx->invoked = true;
> > +       inner_map = bpf_map_lookup_elem(map, key);
> > +       if (!inner_map) {
> > +               ctx->failed = true;
> > +               return 1;
> > +       }
> 
> This doesn't look right. 'val' is not 'u64 *'.
> It probably should be 'struct bpf_map *',
> so lookup shouldn't be necessary.
> 
> map_set_for_each_callback_args() just sets it to PTR_TO_MAP_VALUE.
> It probably should be CONST_PTR_TO_MAP.
> Also for normal hash map for_each_elem 'val' is writeable.
> It shouldn't be in this case.
> So to cleanly support iterating hash_of_maps patch 1 needs more work.

Thanks for the review and pointing out these issues. This all makes
sense, I'll incorporate it into v2.