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Message-ID: <CAL+tcoDALG5pEXEvhrN4e3AWTi8xO-qOt5nLty55hsDiBaRPrA@mail.gmail.com>
Date: Sat, 14 Dec 2024 00:02:48 +0800
From: Jason Xing <kerneljasonxing@...il.com>
To: Martin KaFai Lau <martin.lau@...ux.dev>
Cc: davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
pabeni@...hat.com, dsahern@...nel.org, willemdebruijn.kernel@...il.com,
willemb@...gle.com, ast@...nel.org, daniel@...earbox.net, andrii@...nel.org,
eddyz87@...il.com, song@...nel.org, yonghong.song@...ux.dev,
john.fastabend@...il.com, kpsingh@...nel.org, sdf@...ichev.me,
haoluo@...gle.com, jolsa@...nel.org, bpf@...r.kernel.org,
netdev@...r.kernel.org, Jason Xing <kernelxing@...cent.com>
Subject: Re: [PATCH net-next v4 11/11] bpf: add simple bpf tests in the tx
path for so_timstamping feature
On Fri, Dec 13, 2024 at 9:14 AM Martin KaFai Lau <martin.lau@...ux.dev> wrote:
>
> On 12/7/24 9:38 AM, Jason Xing wrote:
> > From: Jason Xing <kernelxing@...cent.com>
> >
> > Only check if we pass those three key points after we enable the
> > bpf extension for so_timestamping. During each point, we can choose
> > whether to print the current timestamp.
> >
> > Signed-off-by: Jason Xing <kernelxing@...cent.com>
> > ---
> > .../bpf/prog_tests/so_timestamping.c | 97 +++++++++++++
> > .../selftests/bpf/progs/so_timestamping.c | 135 ++++++++++++++++++
> > 2 files changed, 232 insertions(+)
> > create mode 100644 tools/testing/selftests/bpf/prog_tests/so_timestamping.c
> > create mode 100644 tools/testing/selftests/bpf/progs/so_timestamping.c
> >
> > diff --git a/tools/testing/selftests/bpf/prog_tests/so_timestamping.c b/tools/testing/selftests/bpf/prog_tests/so_timestamping.c
> > new file mode 100644
> > index 000000000000..c5978444f9c8
> > --- /dev/null
> > +++ b/tools/testing/selftests/bpf/prog_tests/so_timestamping.c
> > @@ -0,0 +1,97 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/* Copyright (c) 2024 Tencent */
> > +
> > +#define _GNU_SOURCE
> > +#include <sched.h>
> > +#include <linux/socket.h>
> > +#include <linux/tls.h>
> > +#include <net/if.h>
> > +
> > +#include "test_progs.h"
> > +#include "cgroup_helpers.h"
> > +#include "network_helpers.h"
> > +
> > +#include "so_timestamping.skel.h"
> > +
> > +#define CG_NAME "/so-timestamping-test"
> > +
> > +static const char addr4_str[] = "127.0.0.1";
> > +static const char addr6_str[] = "::1";
> > +static struct so_timestamping *skel;
> > +static int cg_fd;
> > +
> > +static int create_netns(void)
> > +{
> > + if (!ASSERT_OK(unshare(CLONE_NEWNET), "create netns"))
> > + return -1;
> > +
> > + if (!ASSERT_OK(system("ip link set dev lo up"), "set lo up"))
> > + return -1;
> > +
> > + return 0;
> > +}
> > +
> > +static void test_tcp(int family)
> > +{
> > + struct so_timestamping__bss *bss = skel->bss;
> > + char buf[] = "testing testing";
> > + int sfd = -1, cfd = -1;
> > + int n;
> > +
> > + memset(bss, 0, sizeof(*bss));
> > +
> > + sfd = start_server(family, SOCK_STREAM,
> > + family == AF_INET6 ? addr6_str : addr4_str, 0, 0);
> > + if (!ASSERT_GE(sfd, 0, "start_server"))
> > + goto out;
> > +
> > + cfd = connect_to_fd(sfd, 0);
> > + if (!ASSERT_GE(cfd, 0, "connect_to_fd_server")) {
> > + close(sfd);
> > + goto out;
> > + }
> > +
> > + n = write(cfd, buf, sizeof(buf));
> > + if (!ASSERT_EQ(n, sizeof(buf), "send to server"))
> > + goto out;
> > +
> > + ASSERT_EQ(bss->nr_active, 1, "nr_active");
> > + ASSERT_EQ(bss->nr_sched, 1, "nr_sched");
> > + ASSERT_EQ(bss->nr_txsw, 1, "nr_txsw");
> > + ASSERT_EQ(bss->nr_ack, 1, "nr_ack");
> > +
> > +out:
> > + if (sfd >= 0)
> > + close(sfd);
> > + if (cfd >= 0)
> > + close(cfd);
> > +}
> > +
> > +void test_so_timestamping(void)
> > +{
> > + cg_fd = test__join_cgroup(CG_NAME);
> > + if (cg_fd < 0)
> > + return;
> > +
> > + if (create_netns())
> > + goto done;
> > +
> > + skel = so_timestamping__open();
> > + if (!ASSERT_OK_PTR(skel, "open skel"))
> > + goto done;
> > +
> > + if (!ASSERT_OK(so_timestamping__load(skel), "load skel"))
> > + goto done;
> > +
> > + skel->links.skops_sockopt =
> > + bpf_program__attach_cgroup(skel->progs.skops_sockopt, cg_fd);
> > + if (!ASSERT_OK_PTR(skel->links.skops_sockopt, "attach cgroup"))
> > + goto done;
> > +
> > + test_tcp(AF_INET6);
> > + test_tcp(AF_INET);
> > +
> > +done:
> > + so_timestamping__destroy(skel);
> > + close(cg_fd);
> > +}
> > diff --git a/tools/testing/selftests/bpf/progs/so_timestamping.c b/tools/testing/selftests/bpf/progs/so_timestamping.c
> > new file mode 100644
> > index 000000000000..f64e94dbd70e
> > --- /dev/null
> > +++ b/tools/testing/selftests/bpf/progs/so_timestamping.c
> > @@ -0,0 +1,135 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/* Copyright (c) 2024 Tencent */
> > +
> > +#include "vmlinux.h"
> > +#include "bpf_tracing_net.h"
> > +#include <bpf/bpf_core_read.h>
> > +#include <bpf/bpf_helpers.h>
> > +#include <bpf/bpf_tracing.h>
> > +#include "bpf_misc.h"
> > +
> > +#define SK_BPF_CB_FLAGS 1009
> > +#define SK_BPF_CB_TX_TIMESTAMPING 1
> > +
> > +int nr_active;
> > +int nr_passive;
> > +int nr_sched;
> > +int nr_txsw;
> > +int nr_ack;
> > +
> > +struct sockopt_test {
> > + int opt;
> > + int new;
> > +};
> > +
> > +static const struct sockopt_test sol_socket_tests[] = {
> > + { .opt = SK_BPF_CB_FLAGS, .new = SK_BPF_CB_TX_TIMESTAMPING, },
> > + { .opt = 0, },
> > +};
> > +
> > +struct loop_ctx {
> > + void *ctx;
> > + struct sock *sk;
> > +};
> > +
> > +struct {
> > + __uint(type, BPF_MAP_TYPE_HASH);
> > + __type(key, u32);
> > + __type(value, u64);
> > + __uint(max_entries, 1024);
> > +} hash_map SEC(".maps");
> > +
> > +static u64 delay_tolerance_nsec = 5000000;
>
> If I count right, 5ms may not a lot for the bpf CI and the test could become
> flaky. Probably good enough to ensure the delay is larger than the previous one.
You're right, initially I set 2ms which make the test flaky. How about
20ms? We cannot ensure each delta (calculated between two tx points)
is larger than the previous one.
>
> > +
> > +static int bpf_test_sockopt_int(void *ctx, struct sock *sk,
> > + const struct sockopt_test *t,
> > + int level)
> > +{
> > + int new, opt;
> > +
> > + opt = t->opt;
> > + new = t->new;
> > +
> > + if (bpf_setsockopt(ctx, level, opt, &new, sizeof(new)))
> > + return 1;
> > +
> > + return 0;
> > +}
> > +
> > +static int bpf_test_socket_sockopt(__u32 i, struct loop_ctx *lc)
> > +{
> > + const struct sockopt_test *t;
> > +
> > + if (i >= ARRAY_SIZE(sol_socket_tests))
> > + return 1;
> > +
> > + t = &sol_socket_tests[i];
> > + if (!t->opt)
> > + return 1;
> > +
> > + return bpf_test_sockopt_int(lc->ctx, lc->sk, t, SOL_SOCKET);
> > +}
> > +
> > +static int bpf_test_sockopt(void *ctx, struct sock *sk)
> > +{
> > + struct loop_ctx lc = { .ctx = ctx, .sk = sk, };
> > + int n;
> > +
> > + n = bpf_loop(ARRAY_SIZE(sol_socket_tests), bpf_test_socket_sockopt, &lc, 0);
> > + if (n != ARRAY_SIZE(sol_socket_tests))
> > + return -1;
> > +
> > + return 0;
> > +}
> > +
> > +static bool bpf_test_delay(struct bpf_sock_ops *skops)
> > +{
> > + u64 timestamp = bpf_ktime_get_ns();
> > + u32 seq = skops->args[2];
> > + u64 *value;
> > +
> > + value = bpf_map_lookup_elem(&hash_map, &seq);
> > + if (value && (timestamp - *value > delay_tolerance_nsec)) {
> > + bpf_printk("time delay: %lu", timestamp - *value);
>
> Please try not to printk in selftests. The bpf CI cannot interpret it
> meaningfully and turn it into a PASS/FAIL signal.
All right.
>
> > + return false;
> > + }
> > +
> > + bpf_map_update_elem(&hash_map, &seq, ×tamp, BPF_ANY);
>
> A nit.
>
> *value = timestamp;
Will fix it.
>
> > + return true;
> > +}
> > +
> > +SEC("sockops")
> > +int skops_sockopt(struct bpf_sock_ops *skops)
> > +{
> > + struct bpf_sock *bpf_sk = skops->sk;
> > + struct sock *sk;
> > +
> > + if (!bpf_sk)
> > + return 1;
> > +
> > + sk = (struct sock *)bpf_skc_to_tcp_sock(bpf_sk);
> > + if (!sk)
> > + return 1;
> > +
> > + switch (skops->op) {
> > + case BPF_SOCK_OPS_ACTIVE_ESTABLISHED_CB:
> > + nr_active += !bpf_test_sockopt(skops, sk);
> > + break;
> > + case BPF_SOCK_OPS_TS_SCHED_OPT_CB:
> > + if (bpf_test_delay(skops))
> > + nr_sched += 1;
> > + break;
> > + case BPF_SOCK_OPS_TS_SW_OPT_CB:
> > + if (bpf_test_delay(skops))
> > + nr_txsw += 1;
> > + break;
> > + case BPF_SOCK_OPS_TS_ACK_OPT_CB:
> > + if (bpf_test_delay(skops))
> > + nr_ack += 1;
> > + break;
>
> The test is a good step forward. Thanks. Instead of one u64 as the map value, I
> think it can be improved to make the test more real to record the individual
> delay. e.g. the following map value:
>
> struct delay_info {
> u64 sendmsg_ns;
> u32 sched_delay; /* SCHED_OPT_CB - sendmsg_ns */
> u32 sw_snd_delay;
> u32 ack_delay;
> };
>
Good advice :)
> and I think a bpf callback during the sendmsg is still needed in the next respin.
Okay, I planned to introduce a new BPF_SOCK_OPS_TS_SENDMSG_OPT_CB
after this patchset gets merged. Since you've already asked, I will
surely follow :) Thanks.
>
> > + }
> > +
> > + return 1;
> > +}
> > +
> > +char _license[] SEC("license") = "GPL";
>
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