Re: [PATCH bpf-next 2/2] bpf: Add tests for bpf_sk_storage to bpf_tcp_ca

[Yonghong Song <yhs@fb.com>]

On 3/19/20 4:50 PM, Martin KaFai Lau wrote:
> This patch adds test to exercise the bpf_sk_storage_get()
> and bpf_sk_storage_delete() helper from the bpf_dctcp.c.
> 
> Signed-off-by: Martin KaFai Lau <kafai@fb.com>
> ---
>   .../selftests/bpf/prog_tests/bpf_tcp_ca.c     | 28 +++++++++++++++++--
>   tools/testing/selftests/bpf/progs/bpf_dctcp.c | 16 +++++++++++
>   2 files changed, 41 insertions(+), 3 deletions(-)
> 
> 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 8482bbc67eec..9aaecce0bc3c 100644
> --- a/tools/testing/selftests/bpf/prog_tests/bpf_tcp_ca.c
> +++ b/tools/testing/selftests/bpf/prog_tests/bpf_tcp_ca.c
> @@ -11,6 +11,7 @@
>   static const unsigned int total_bytes = 10 * 1024 * 1024;
>   static const struct timeval timeo_sec = { .tv_sec = 10 };
>   static const size_t timeo_optlen = sizeof(timeo_sec);
> +static int expected_stg = 0xeB9F;
>   static int stop, duration;
>   
>   static int settimeo(int fd)
> @@ -88,7 +89,7 @@ static void *server(void *arg)
>   	return NULL;
>   }
>   
> -static void do_test(const char *tcp_ca)
> +static void do_test(const char *tcp_ca, const struct bpf_map *sk_stg_map)
>   {
>   	struct sockaddr_in6 sa6 = {};
>   	ssize_t nr_recv = 0, bytes = 0;
> @@ -110,6 +111,14 @@ static void do_test(const char *tcp_ca)
>   		return;
>   	}
>   
> +	if (sk_stg_map) {
> +		err = bpf_map_update_elem(bpf_map__fd(sk_stg_map), &fd,
> +					  &expected_stg, BPF_NOEXIST);
> +		if (CHECK(err, "bpf_map_update_elem(sk_stg_map)",
> +			  "err:%d errno:%d\n", err, errno))
> +			goto done;
> +	}
> +
>   	if (settcpca(lfd, tcp_ca) || settcpca(fd, tcp_ca) ||
>   	    settimeo(lfd) || settimeo(fd))
>   		goto done;
> @@ -149,6 +158,16 @@ static void do_test(const char *tcp_ca)
>   	CHECK(bytes != total_bytes, "recv", "%zd != %u nr_recv:%zd errno:%d\n",
>   	      bytes, total_bytes, nr_recv, errno);

Should the control go to "wait_thread" here if failure?

>   
> +	if (sk_stg_map) {
> +		int tmp_stg;
> +
> +		err = bpf_map_lookup_elem(bpf_map__fd(sk_stg_map), &fd,
> +					  &tmp_stg);
> +		CHECK(!err || errno != ENOENT,
> +		      "bpf_map_lookup_elem(sk_stg_map)",
> +		      "err:%d errno:%d\n", err, errno);
> +	}
> +
>   wait_thread:
>   	WRITE_ONCE(stop, 1);
>   	pthread_join(srv_thread, &thread_ret);
> @@ -175,7 +194,7 @@ static void test_cubic(void)
>   		return;
>   	}
>   
> -	do_test("bpf_cubic");
> +	do_test("bpf_cubic", NULL);
>   
>   	bpf_link__destroy(link);
>   	bpf_cubic__destroy(cubic_skel);
> @@ -197,7 +216,10 @@ static void test_dctcp(void)
>   		return;
>   	}
>   
> -	do_test("bpf_dctcp");
> +	do_test("bpf_dctcp", dctcp_skel->maps.sk_stg_map);
> +	CHECK(dctcp_skel->bss->stg_result != expected_stg,
> +	      "Unexpected stg_result", "stg_result (%x) != expected_stg (%x)\n",
> +	      dctcp_skel->bss->stg_result, expected_stg);
>   
>   	bpf_link__destroy(link);
>   	bpf_dctcp__destroy(dctcp_skel);
> diff --git a/tools/testing/selftests/bpf/progs/bpf_dctcp.c b/tools/testing/selftests/bpf/progs/bpf_dctcp.c
> index 127ea762a062..5c1fc584f3ae 100644
> --- a/tools/testing/selftests/bpf/progs/bpf_dctcp.c
> +++ b/tools/testing/selftests/bpf/progs/bpf_dctcp.c
> @@ -6,6 +6,7 @@
>    * the kernel BPF logic.
>    */
>   
> +#include <stddef.h>
>   #include <linux/bpf.h>
>   #include <linux/types.h>
>   #include <bpf/bpf_helpers.h>
> @@ -14,6 +15,15 @@
>   
>   char _license[] SEC("license") = "GPL";
>   
> +static volatile int stg_result;

"int stg_result = 0;" should work too.

> +
> +struct {
> +	__uint(type, BPF_MAP_TYPE_SK_STORAGE);
> +	__uint(map_flags, BPF_F_NO_PREALLOC);
> +	__type(key, int);
> +	__type(value, int);
> +} sk_stg_map SEC(".maps");
> +
>   #define DCTCP_MAX_ALPHA	1024U
>   
>   struct dctcp {
> @@ -43,12 +53,18 @@ void BPF_PROG(dctcp_init, struct sock *sk)
>   {
>   	const struct tcp_sock *tp = tcp_sk(sk);
>   	struct dctcp *ca = inet_csk_ca(sk);
> +	int *stg;
>   
>   	ca->prior_rcv_nxt = tp->rcv_nxt;
>   	ca->dctcp_alpha = min(dctcp_alpha_on_init, DCTCP_MAX_ALPHA);
>   	ca->loss_cwnd = 0;
>   	ca->ce_state = 0;
>   
> +	stg = bpf_sk_storage_get(&sk_stg_map, (void *)tp, NULL, 0);
> +	if (stg) {
> +		stg_result = *stg;
> +		bpf_sk_storage_delete(&sk_stg_map, (void *)tp);
> +	}
>   	dctcp_reset(tp, ca);
>   }
>   
>