[bpf-next,7/7] selftests/bpf: Test switching TCP Congestion Control algorithms.

Commit Message

Kui-Feng Lee Feb. 14, 2023, 10:17 p.m. UTC

Create a pair of sockets that utilize the congestion control algorithm
under a particular name. Then switch up this congestion control
algorithm to another implementation and check whether newly created
connections using the same cc name now run the new implementation.

Signed-off-by: Kui-Feng Lee <[e-mail]>
---
 .../selftests/bpf/prog_tests/bpf_tcp_ca.c     | 48 ++++++++++++
 .../selftests/bpf/progs/tcp_ca_update.c       | 75 +++++++++++++++++++
 2 files changed, 123 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/progs/tcp_ca_update.c

Comments

Andrii Nakryiko Feb. 16, 2023, 10:50 p.m. UTC | #1

On Tue, Feb 14, 2023 at 2:17 PM Kui-Feng Lee <[e-mail]> wrote:
>
> Create a pair of sockets that utilize the congestion control algorithm
> under a particular name. Then switch up this congestion control
> algorithm to another implementation and check whether newly created
> connections using the same cc name now run the new implementation.
>
> Signed-off-by: Kui-Feng Lee <[e-mail]>
> ---
>  .../selftests/bpf/prog_tests/bpf_tcp_ca.c     | 48 ++++++++++++
>  .../selftests/bpf/progs/tcp_ca_update.c       | 75 +++++++++++++++++++
>  2 files changed, 123 insertions(+)
>  create mode 100644 tools/testing/selftests/bpf/progs/tcp_ca_update.c
>

[...]

> diff --git a/tools/testing/selftests/bpf/progs/tcp_ca_update.c b/tools/testing/selftests/bpf/progs/tcp_ca_update.c
> new file mode 100644
> index 000000000000..cf51fe54ac01
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/progs/tcp_ca_update.c
> @@ -0,0 +1,75 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +#include "vmlinux.h"
> +
> +#include <bpf/bpf_helpers.h>
> +#include <bpf/bpf_tracing.h>
> +
> +char _license[] SEC("license") = "GPL";
> +
> +int ca1_cnt = 0;
> +int ca2_cnt = 0;
> +
> +#define USEC_PER_SEC 1000000UL
> +
> +#define min(a, b) ((a) < (b) ? (a) : (b))
> +
> +static inline struct tcp_sock *tcp_sk(const struct sock *sk)
> +{
> +       return (struct tcp_sock *)sk;
> +}
> +
> +SEC("struct_ops/ca_update_init")
> +void BPF_PROG(ca_update_init, struct sock *sk)
> +{
> +#ifdef ENABLE_ATOMICS_TESTS

it's been 2 years since atomics were added to Clang, I think it's fine
to just assume atomic operations are supported and not do the
ENABLE_ATOMICS_TEST (and I'd clean up ENABLE_ATOMICS_TESTS now as
well)

> +       __sync_bool_compare_and_swap(&sk->sk_pacing_status, SK_PACING_NONE,
> +                                    SK_PACING_NEEDED);
> +#else
> +       sk->sk_pacing_status = SK_PACING_NEEDED;
> +#endif
> +}
> +
> +SEC("struct_ops/ca_update_1_cong_control")
> +void BPF_PROG(ca_update_1_cong_control, struct sock *sk,
> +             const struct rate_sample *rs)
> +{
> +       ca1_cnt++;
> +}
> +
> +SEC("struct_ops/ca_update_2_cong_control")
> +void BPF_PROG(ca_update_2_cong_control, struct sock *sk,
> +             const struct rate_sample *rs)
> +{
> +       ca2_cnt++;
> +}
> +
> +SEC("struct_ops/ca_update_ssthresh")
> +__u32 BPF_PROG(ca_update_ssthresh, struct sock *sk)
> +{
> +       return tcp_sk(sk)->snd_ssthresh;
> +}
> +
> +SEC("struct_ops/ca_update_undo_cwnd")
> +__u32 BPF_PROG(ca_update_undo_cwnd, struct sock *sk)
> +{
> +       return tcp_sk(sk)->snd_cwnd;
> +}
> +
> +SEC(".struct_ops")
> +struct tcp_congestion_ops ca_update_1 = {
> +       .init = (void *)ca_update_init,
> +       .cong_control = (void *)ca_update_1_cong_control,
> +       .ssthresh = (void *)ca_update_ssthresh,
> +       .undo_cwnd = (void *)ca_update_undo_cwnd,
> +       .name = "tcp_ca_update",
> +};
> +
> +SEC(".struct_ops")
> +struct tcp_congestion_ops ca_update_2 = {
> +       .init = (void *)ca_update_init,
> +       .cong_control = (void *)ca_update_2_cong_control,
> +       .ssthresh = (void *)ca_update_ssthresh,
> +       .undo_cwnd = (void *)ca_update_undo_cwnd,
> +       .name = "tcp_ca_update",
> +};
> --
> 2.30.2
>

Kui-Feng Lee Feb. 18, 2023, 12:23 a.m. UTC | #2

On 2/16/23 14:50, Andrii Nakryiko wrote:
> On Tue, Feb 14, 2023 at 2:17 PM Kui-Feng Lee <[e-mail]> wrote:
>>
>> Create a pair of sockets that utilize the congestion control algorithm
>> under a particular name. Then switch up this congestion control
>> algorithm to another implementation and check whether newly created
>> connections using the same cc name now run the new implementation.
>>
>> Signed-off-by: Kui-Feng Lee <[e-mail]>
>> ---
>>   .../selftests/bpf/prog_tests/bpf_tcp_ca.c     | 48 ++++++++++++
>>   .../selftests/bpf/progs/tcp_ca_update.c       | 75 +++++++++++++++++++
>>   2 files changed, 123 insertions(+)
>>   create mode 100644 tools/testing/selftests/bpf/progs/tcp_ca_update.c
>>
> 
> [...]
> 
>> diff --git a/tools/testing/selftests/bpf/progs/tcp_ca_update.c b/tools/testing/selftests/bpf/progs/tcp_ca_update.c
>> new file mode 100644
>> index 000000000000..cf51fe54ac01
>> --- /dev/null
>> +++ b/tools/testing/selftests/bpf/progs/tcp_ca_update.c
>> @@ -0,0 +1,75 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +
>> +#include "vmlinux.h"
>> +
>> +#include <bpf/bpf_helpers.h>
>> +#include <bpf/bpf_tracing.h>
>> +
>> +char _license[] SEC("license") = "GPL";
>> +
>> +int ca1_cnt = 0;
>> +int ca2_cnt = 0;
>> +
>> +#define USEC_PER_SEC 1000000UL
>> +
>> +#define min(a, b) ((a) < (b) ? (a) : (b))
>> +
>> +static inline struct tcp_sock *tcp_sk(const struct sock *sk)
>> +{
>> +       return (struct tcp_sock *)sk;
>> +}
>> +
>> +SEC("struct_ops/ca_update_init")
>> +void BPF_PROG(ca_update_init, struct sock *sk)
>> +{
>> +#ifdef ENABLE_ATOMICS_TESTS
> 
> it's been 2 years since atomics were added to Clang, I think it's fine
> to just assume atomic operations are supported and not do the
> ENABLE_ATOMICS_TEST (and I'd clean up ENABLE_ATOMICS_TESTS now as
> well)

Sure!

> 
>> +       __sync_bool_compare_and_swap(&sk->sk_pacing_status, SK_PACING_NONE,
>> +                                    SK_PACING_NEEDED);
>> +#else
>> +       sk->sk_pacing_status = SK_PACING_NEEDED;
>> +#endif
>> +}
>> +
>> +SEC("struct_ops/ca_update_1_cong_control")
>> +void BPF_PROG(ca_update_1_cong_control, struct sock *sk,
>> +             const struct rate_sample *rs)
>> +{
>> +       ca1_cnt++;
>> +}
>> +
>> +SEC("struct_ops/ca_update_2_cong_control")
>> +void BPF_PROG(ca_update_2_cong_control, struct sock *sk,
>> +             const struct rate_sample *rs)
>> +{
>> +       ca2_cnt++;
>> +}
>> +
>> +SEC("struct_ops/ca_update_ssthresh")
>> +__u32 BPF_PROG(ca_update_ssthresh, struct sock *sk)
>> +{
>> +       return tcp_sk(sk)->snd_ssthresh;
>> +}
>> +
>> +SEC("struct_ops/ca_update_undo_cwnd")
>> +__u32 BPF_PROG(ca_update_undo_cwnd, struct sock *sk)
>> +{
>> +       return tcp_sk(sk)->snd_cwnd;
>> +}
>> +
>> +SEC(".struct_ops")
>> +struct tcp_congestion_ops ca_update_1 = {
>> +       .init = (void *)ca_update_init,
>> +       .cong_control = (void *)ca_update_1_cong_control,
>> +       .ssthresh = (void *)ca_update_ssthresh,
>> +       .undo_cwnd = (void *)ca_update_undo_cwnd,
>> +       .name = "tcp_ca_update",
>> +};
>> +
>> +SEC(".struct_ops")
>> +struct tcp_congestion_ops ca_update_2 = {
>> +       .init = (void *)ca_update_init,
>> +       .cong_control = (void *)ca_update_2_cong_control,
>> +       .ssthresh = (void *)ca_update_ssthresh,
>> +       .undo_cwnd = (void *)ca_update_undo_cwnd,
>> +       .name = "tcp_ca_update",
>> +};
>> --
>> 2.30.2
>>

Patch

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 e980188d4124..89477e4c9a24 100644
--- a/tools/testing/selftests/bpf/prog_tests/bpf_tcp_ca.c
+++ b/tools/testing/selftests/bpf/prog_tests/bpf_tcp_ca.c
@@ -8,6 +8,7 @@ 
 #include "bpf_dctcp.skel.h"
 #include "bpf_cubic.skel.h"
 #include "bpf_tcp_nogpl.skel.h"
+#include "tcp_ca_update.skel.h"
 #include "bpf_dctcp_release.skel.h"
 #include "tcp_ca_write_sk_pacing.skel.h"
 #include "tcp_ca_incompl_cong_ops.skel.h"
@@ -381,6 +382,51 @@  static void test_unsupp_cong_op(void)
 	libbpf_set_print(old_print_fn);
 }
 
+static void test_update_ca(void)
+{
+	struct tcp_ca_update *skel;
+	struct bpf_link *link;
+	int saved_ca1_cnt;
+	int err;
+
+	skel = tcp_ca_update__open();
+	if (!ASSERT_OK_PTR(skel, "open"))
+		return;
+
+	err = bpf_map__set_map_flags(skel->maps.ca_update_1,
+				     bpf_map__map_flags(skel->maps.ca_update_1) | BPF_F_LINK);
+	if (!ASSERT_OK(err, "set_map_flags_1"))
+		return;
+
+	err = bpf_map__set_map_flags(skel->maps.ca_update_2,
+				     bpf_map__map_flags(skel->maps.ca_update_2) | BPF_F_LINK);
+	if (!ASSERT_OK(err, "set_map_flags_2"))
+		return;
+
+	err = tcp_ca_update__load(skel);
+	if (!ASSERT_OK(err, "load")) {
+		tcp_ca_update__destroy(skel);
+		return;
+	}
+
+	link = bpf_map__attach_struct_ops(skel->maps.ca_update_1);
+	ASSERT_OK_PTR(link, "attach_struct_ops");
+
+	do_test("tcp_ca_update", NULL);
+	saved_ca1_cnt = skel->bss->ca1_cnt;
+	ASSERT_GT(saved_ca1_cnt, 0, "ca1_ca1_cnt");
+
+	err = bpf_link__update_struct_ops(link, skel->maps.ca_update_2);
+	ASSERT_OK(err, "update_struct_ops");
+
+	do_test("tcp_ca_update", NULL);
+	ASSERT_EQ(skel->bss->ca1_cnt, saved_ca1_cnt, "ca2_ca1_cnt");
+	ASSERT_GT(skel->bss->ca2_cnt, 0, "ca2_ca2_cnt");
+
+	bpf_link__destroy(link);
+	tcp_ca_update__destroy(skel);
+}
+
 void test_bpf_tcp_ca(void)
 {
 	if (test__start_subtest("dctcp"))
@@ -399,4 +445,6 @@  void test_bpf_tcp_ca(void)
 		test_incompl_cong_ops();
 	if (test__start_subtest("unsupp_cong_op"))
 		test_unsupp_cong_op();
+	if (test__start_subtest("update_ca"))
+		test_update_ca();
 }
diff --git a/tools/testing/selftests/bpf/progs/tcp_ca_update.c b/tools/testing/selftests/bpf/progs/tcp_ca_update.c
new file mode 100644
index 000000000000..cf51fe54ac01
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/tcp_ca_update.c
@@ -0,0 +1,75 @@ 
+// SPDX-License-Identifier: GPL-2.0
+
+#include "vmlinux.h"
+
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+char _license[] SEC("license") = "GPL";
+
+int ca1_cnt = 0;
+int ca2_cnt = 0;
+
+#define USEC_PER_SEC 1000000UL
+
+#define min(a, b) ((a) < (b) ? (a) : (b))
+
+static inline struct tcp_sock *tcp_sk(const struct sock *sk)
+{
+	return (struct tcp_sock *)sk;
+}
+
+SEC("struct_ops/ca_update_init")
+void BPF_PROG(ca_update_init, struct sock *sk)
+{
+#ifdef ENABLE_ATOMICS_TESTS
+	__sync_bool_compare_and_swap(&sk->sk_pacing_status, SK_PACING_NONE,
+				     SK_PACING_NEEDED);
+#else
+	sk->sk_pacing_status = SK_PACING_NEEDED;
+#endif
+}
+
+SEC("struct_ops/ca_update_1_cong_control")
+void BPF_PROG(ca_update_1_cong_control, struct sock *sk,
+	      const struct rate_sample *rs)
+{
+	ca1_cnt++;
+}
+
+SEC("struct_ops/ca_update_2_cong_control")
+void BPF_PROG(ca_update_2_cong_control, struct sock *sk,
+	      const struct rate_sample *rs)
+{
+	ca2_cnt++;
+}
+
+SEC("struct_ops/ca_update_ssthresh")
+__u32 BPF_PROG(ca_update_ssthresh, struct sock *sk)
+{
+	return tcp_sk(sk)->snd_ssthresh;
+}
+
+SEC("struct_ops/ca_update_undo_cwnd")
+__u32 BPF_PROG(ca_update_undo_cwnd, struct sock *sk)
+{
+	return tcp_sk(sk)->snd_cwnd;
+}
+
+SEC(".struct_ops")
+struct tcp_congestion_ops ca_update_1 = {
+	.init = (void *)ca_update_init,
+	.cong_control = (void *)ca_update_1_cong_control,
+	.ssthresh = (void *)ca_update_ssthresh,
+	.undo_cwnd = (void *)ca_update_undo_cwnd,
+	.name = "tcp_ca_update",
+};
+
+SEC(".struct_ops")
+struct tcp_congestion_ops ca_update_2 = {
+	.init = (void *)ca_update_init,
+	.cong_control = (void *)ca_update_2_cong_control,
+	.ssthresh = (void *)ca_update_ssthresh,
+	.undo_cwnd = (void *)ca_update_undo_cwnd,
+	.name = "tcp_ca_update",
+};