linux-kernel - Re: [PATCH net v4 2/2] bpf: selftests: send packet to devmap redirect XDP

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Message-ID: <c4ee29b6-5dfc-44f6-af5c-02d042b42cc0@linux.dev>
Date: Wed, 2 Oct 2024 14:24:08 -0700
From: Martin KaFai Lau <martin.lau@...ux.dev>
To: Florian Kauer <florian.kauer@...utronix.de>
Cc: Alexei Starovoitov <ast@...nel.org>,
 Daniel Borkmann <daniel@...earbox.net>, "David S. Miller"
 <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>,
 Jesper Dangaard Brouer <hawk@...nel.org>,
 John Fastabend <john.fastabend@...il.com>,
 Andrii Nakryiko <andrii@...nel.org>, Eduard Zingerman <eddyz87@...il.com>,
 Song Liu <song@...nel.org>, Yonghong Song <yonghong.song@...ux.dev>,
 KP Singh <kpsingh@...nel.org>, Stanislav Fomichev <sdf@...ichev.me>,
 Hao Luo <haoluo@...gle.com>, Jiri Olsa <jolsa@...nel.org>,
 Toke Høiland-Jørgensen <toke@...hat.com>,
 David Ahern <dsahern@...nel.org>, Hangbin Liu <liuhangbin@...il.com>,
 Mykola Lysenko <mykolal@...com>, Shuah Khan <shuah@...nel.org>,
 netdev@...r.kernel.org, bpf@...r.kernel.org, linux-kernel@...r.kernel.org,
 Jesper Dangaard Brouer <brouer@...hat.com>, linux-kselftest@...r.kernel.org
Subject: Re: [PATCH net v4 2/2] bpf: selftests: send packet to devmap redirect
 XDP

On 9/11/24 1:41 AM, Florian Kauer wrote:
> @@ -25,14 +28,11 @@ static void test_xdp_with_devmap_helpers(void)
>   	if (!ASSERT_OK_PTR(skel, "test_xdp_with_devmap_helpers__open_and_load"))
>   		return;
>   
> -	dm_fd = bpf_program__fd(skel->progs.xdp_redir_prog);
> -	err = bpf_xdp_attach(IFINDEX_LO, dm_fd, XDP_FLAGS_SKB_MODE, NULL);
> +	dm_fd_redir = bpf_program__fd(skel->progs.xdp_redir_prog);
> +	err = bpf_xdp_attach(IFINDEX_LO, dm_fd_redir, XDP_FLAGS_SKB_MODE, NULL);
>   	if (!ASSERT_OK(err, "Generic attach of program with 8-byte devmap"))
>   		goto out_close;
>   
> -	err = bpf_xdp_detach(IFINDEX_LO, XDP_FLAGS_SKB_MODE, NULL);
> -	ASSERT_OK(err, "XDP program detach");
> -
>   	dm_fd = bpf_program__fd(skel->progs.xdp_dummy_dm);
>   	map_fd = bpf_map__fd(skel->maps.dm_ports);
>   	err = bpf_prog_get_info_by_fd(dm_fd, &info, &len);
> @@ -47,6 +47,23 @@ static void test_xdp_with_devmap_helpers(void)
>   	ASSERT_OK(err, "Read devmap entry");
>   	ASSERT_EQ(info.id, val.bpf_prog.id, "Match program id to devmap entry prog_id");
>   
> +	/* send a packet to trigger any potential bugs in there */
> +	char data[10] = {};
> +	DECLARE_LIBBPF_OPTS(bpf_test_run_opts, opts,
> +			    .data_in = &data,
> +			    .data_size_in = 10,
> +			    .flags = BPF_F_TEST_XDP_LIVE_FRAMES,
> +			    .repeat = 1,
> +		);
> +	err = bpf_prog_test_run_opts(dm_fd_redir, &opts);

I am seeing pr_warn on "Driver unsupported XDP return value on prog 
xdp_redir_prog...". There is an existing bug in xdp_redir_prog(). I fixed it 
with this:

SEC("xdp")
int xdp_redir_prog(struct xdp_md *ctx)
{
-	return bpf_redirect_map(&dm_ports, 1, 0);
+	return bpf_redirect_map(&dm_ports, 0, 0);
}

and also wrapped the above "lo" test in its own netns also.

Applied to the bpf tree. Thanks.