Re: [PATCH bpf-next v2 1/4] selftests/bpf: Use post_socket_cb in connect_to_fd_opts

[Martin KaFai Lau <martin.lau@linux.dev>]

On 5/14/24 9:20 PM, Geliang Tang wrote:
> From: Geliang Tang <tanggeliang@kylinos.cn>
> 
> Since the post_socket_cb() callback is added in struct network_helper_opts,
> it's make sense to use it not only in __start_server(), but also in
> connect_to_fd_opts(). Then it can be used to set TCP_CONGESTION sockopt.
> 
> Add a post_socket_opts type member cb_opts into struct network_helper_opts,
> then cc can be moved into struct post_socket_opts from network_helper_opts.
> Define a new callback cc_cb() to set TCP_CONGESTION sockopt, and set it to
> post_socket_cb pointer.
> 
> Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
> ---
>   tools/testing/selftests/bpf/network_helpers.c       | 5 ++---
>   tools/testing/selftests/bpf/network_helpers.h       | 6 ++++--
>   tools/testing/selftests/bpf/prog_tests/bpf_tcp_ca.c | 9 ++++++++-
>   3 files changed, 14 insertions(+), 6 deletions(-)
> 
> diff --git a/tools/testing/selftests/bpf/network_helpers.c b/tools/testing/selftests/bpf/network_helpers.c
> index 35250e6cde7f..d97f8a669b38 100644
> --- a/tools/testing/selftests/bpf/network_helpers.c
> +++ b/tools/testing/selftests/bpf/network_helpers.c
> @@ -338,9 +338,8 @@ int connect_to_fd_opts(int server_fd, const struct network_helper_opts *opts)
>   	if (settimeo(fd, opts->timeout_ms))
>   		goto error_close;
>   
> -	if (opts->cc && opts->cc[0] &&
> -	    setsockopt(fd, SOL_TCP, TCP_CONGESTION, opts->cc,
> -		       strlen(opts->cc) + 1))
> +	if (opts->post_socket_cb &&
> +	    opts->post_socket_cb(fd, &opts->cb_opts))
>   		goto error_close;
>   
>   	if (!opts->noconnect)
> diff --git a/tools/testing/selftests/bpf/network_helpers.h b/tools/testing/selftests/bpf/network_helpers.h
> index 883c7ea9d8d5..e44a6e5d8344 100644
> --- a/tools/testing/selftests/bpf/network_helpers.h
> +++ b/tools/testing/selftests/bpf/network_helpers.h
> @@ -21,16 +21,18 @@ typedef __u16 __sum16;
>   #define VIP_NUM 5
>   #define MAGIC_BYTES 123
>   
> -struct post_socket_opts {};
> +struct post_socket_opts {
> +	const char *cc;
> +};

 From looking its usage in this set, it has cc name and map fd in it. It becomes 
clear that it is not possible to have one generic/common "struct 
post_socket_opts" for all tests.

>   
>   struct network_helper_opts {
> -	const char *cc;
>   	int timeout_ms;
>   	bool must_fail;
>   	bool noconnect;
>   	int type;
>   	int proto;
>   	int (*post_socket_cb)(int fd, const struct post_socket_opts *opts);
> +	struct post_socket_opts cb_opts;

It is better to have the individual test define its own callback opts struct. 
Something like this:

/* network_helpers.h */
struct network_helper_opts {
	/* ... */
	int (*post_socket_cb)(int fd, void *opts);
	void *post_socket_opts;
};

/* bpf_tcp_ca.c */
struct cb_opts {
	const char *cc;
	int map_fd;
};

struct cb_opts cb_opts = {
	.cc = "bpf_dctcp",
	.map_fd = fd,
};

struct network_helper_opts opts = {
	.post_socket_cb = stg_post_socket_cb,
	.post_sock_opts = &cb_opts,
};

pw-bot: cr

>   };
>   
>   /* ipv4 test vector */
> diff --git a/tools/testing/selftests/bpf/prog_tests/bpf_tcp_ca.c b/tools/testing/selftests/bpf/prog_tests/bpf_tcp_ca.c
> index 0aca02532794..9bc909fa0833 100644
> --- a/tools/testing/selftests/bpf/prog_tests/bpf_tcp_ca.c
> +++ b/tools/testing/selftests/bpf/prog_tests/bpf_tcp_ca.c
> @@ -81,6 +81,12 @@ static void do_test(const char *tcp_ca, const struct bpf_map *sk_stg_map)
>   	close(fd);
>   }
>   
> +static int cc_cb(int fd, const struct post_socket_opts *opts)
> +{
> +	return setsockopt(fd, SOL_TCP, TCP_CONGESTION, opts->cc,
> +			  strlen(opts->cc) + 1);
> +}
> +
>   static void test_cubic(void)
>   {
>   	struct bpf_cubic *cubic_skel;
> @@ -172,7 +178,8 @@ static void test_dctcp_fallback(void)
>   {
>   	int err, lfd = -1, cli_fd = -1, srv_fd = -1;
>   	struct network_helper_opts opts = {
> -		.cc = "cubic",
> +		.cb_opts.cc = "cubic",
> +		.post_socket_cb = cc_cb,
>   	};
>   	struct bpf_dctcp *dctcp_skel;
>   	struct bpf_link *link = NULL;