linux-kernel - Re: [PATCH bpf-next v3 6/6] bpf: Test bpf_sk_storage

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Date:   Thu, 26 Nov 2020 23:02:34 -0800
From:   Yonghong Song <yhs@...com>
To:     Florent Revest <revest@...omium.org>, <bpf@...r.kernel.org>
CC:     <viro@...iv.linux.org.uk>, <davem@...emloft.net>,
        <kuba@...nel.org>, <ast@...nel.org>, <daniel@...earbox.net>,
        <kafai@...com>, <andrii@...nel.org>, <kpsingh@...omium.org>,
        <revest@...gle.com>, <linux-kernel@...r.kernel.org>,
        <netdev@...r.kernel.org>
Subject: Re: [PATCH bpf-next v3 6/6] bpf: Test bpf_sk_storage_get in tcp
 iterators



On 11/26/20 8:44 AM, Florent Revest wrote:
> This extends the existing bpf_sk_storage_get test where a socket is
> created and tagged with its creator's pid by a task_file iterator.
> 
> A TCP iterator is now also used at the end of the test to negate the
> values already stored in the local storage. The test therefore expects
> -getpid() to be stored in the local storage.
> 
> Signed-off-by: Florent Revest <revest@...gle.com>

Ack with a minor comment below.

Acked-by: Yonghong Song <yhs@...com>

> ---
>   .../selftests/bpf/prog_tests/bpf_iter.c        | 13 +++++++++++++
>   .../progs/bpf_iter_bpf_sk_storage_helpers.c    | 18 ++++++++++++++++++
>   2 files changed, 31 insertions(+)
> 
> diff --git a/tools/testing/selftests/bpf/prog_tests/bpf_iter.c b/tools/testing/selftests/bpf/prog_tests/bpf_iter.c
> index 9336d0f18331..b8362147c9e3 100644
> --- a/tools/testing/selftests/bpf/prog_tests/bpf_iter.c
> +++ b/tools/testing/selftests/bpf/prog_tests/bpf_iter.c
> @@ -978,6 +978,8 @@ static void test_bpf_sk_storage_delete(void)
>   /* This creates a socket and its local storage. It then runs a task_iter BPF
>    * program that replaces the existing socket local storage with the tgid of the
>    * only task owning a file descriptor to this socket, this process, prog_tests.
> + * It then runs a tcp socket iterator that negates the value in the existing
> + * socket local storage, the test verifies that the resulting value is -pid.
>    */
>   static void test_bpf_sk_storage_get(void)
>   {
> @@ -994,6 +996,10 @@ static void test_bpf_sk_storage_get(void)
>   	if (CHECK(sock_fd < 0, "socket", "errno: %d\n", errno))
>   		goto out;
>   
> +	err = listen(sock_fd, 1);
> +	if (CHECK(err != 0, "listen", "errno: %d\n", errno))
> +		goto out;
> +
>   	map_fd = bpf_map__fd(skel->maps.sk_stg_map);
>   
>   	err = bpf_map_update_elem(map_fd, &sock_fd, &val, BPF_NOEXIST);
> @@ -1007,6 +1013,13 @@ static void test_bpf_sk_storage_get(void)
>   	      "map value wasn't set correctly (expected %d, got %d, err=%d)\n",
>   	      getpid(), val, err);
>   
> +	do_dummy_read(skel->progs.negate_socket_local_storage);
> +
> +	err = bpf_map_lookup_elem(map_fd, &sock_fd, &val);
> +	CHECK(err || val != -getpid(), "bpf_map_lookup_elem",
> +	      "map value wasn't set correctly (expected %d, got %d, err=%d)\n",
> +	      -getpid(), val, err);
> +
>   close_socket:
>   	close(sock_fd);
>   out:
> diff --git a/tools/testing/selftests/bpf/progs/bpf_iter_bpf_sk_storage_helpers.c b/tools/testing/selftests/bpf/progs/bpf_iter_bpf_sk_storage_helpers.c
> index d7a7a802d172..b3f0cb139c55 100644
> --- a/tools/testing/selftests/bpf/progs/bpf_iter_bpf_sk_storage_helpers.c
> +++ b/tools/testing/selftests/bpf/progs/bpf_iter_bpf_sk_storage_helpers.c
> @@ -46,3 +46,21 @@ int fill_socket_owner(struct bpf_iter__task_file *ctx)
>   	return 0;
>   }
>   
> +SEC("iter/tcp")
> +int negate_socket_local_storage(struct bpf_iter__tcp *ctx)
> +{
> +	struct sock_common *sk_common = ctx->sk_common;
> +	int *sock_tgid;
> +
> +	if (!sk_common)
> +		return 0;
> +
> +	sock_tgid = bpf_sk_storage_get(&sk_stg_map, sk_common, 0, 0);
> +	if (!sock_tgid)
> +		return 0;
> +
> +	*sock_tgid = -*sock_tgid;
> +
> +	return 0;
> +}
> +

extra empty line here.

>