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Message-ID: <60991e56-dad5-c310-86bb-102ebf756b6b@linux.dev>
Date: Wed, 22 Feb 2023 14:35:59 -0800
From: Martin KaFai Lau <martin.lau@...ux.dev>
To: "D. Wythe" <alibuda@...ux.alibaba.com>
Cc: kuba@...nel.org, davem@...emloft.net, netdev@...r.kernel.org,
linux-s390@...r.kernel.org, linux-rdma@...r.kernel.org,
bpf@...r.kernel.org, kgraul@...ux.ibm.com, wenjia@...ux.ibm.com,
jaka@...ux.ibm.com, ast@...nel.org, daniel@...earbox.net,
andrii@...nel.org
Subject: Re: [PATCH bpf-next v2 2/2] bpf/selftests: add selftest for SMC bpf
capability
On 2/21/23 4:18 AM, D. Wythe wrote:
> From: "D. Wythe" <alibuda@...ux.alibaba.com>
>
> This PATCH adds a tiny selftest for SMC bpf capability,
> making decisions on whether to use SMC by collecting
> certain information from kernel smc sock.
>
> Follow the steps below to run this test.
>
> make -C tools/testing/selftests/bpf
> cd tools/testing/selftests/bpf
> sudo ./test_progs -t bpf_smc
>
> Results shows:
> 18 bpf_smc:OK
> Summary: 1/0 PASSED, 0 SKIPPED, 0 FAILED
>
> Signed-off-by: D. Wythe <alibuda@...ux.alibaba.com>
> ---
> tools/testing/selftests/bpf/prog_tests/bpf_smc.c | 39 +++
> tools/testing/selftests/bpf/progs/bpf_smc.c | 315 +++++++++++++++++++++++
> 2 files changed, 354 insertions(+)
> create mode 100644 tools/testing/selftests/bpf/prog_tests/bpf_smc.c
> create mode 100644 tools/testing/selftests/bpf/progs/bpf_smc.c
>
> diff --git a/tools/testing/selftests/bpf/prog_tests/bpf_smc.c b/tools/testing/selftests/bpf/prog_tests/bpf_smc.c
> new file mode 100644
> index 0000000..b143932
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/prog_tests/bpf_smc.c
> @@ -0,0 +1,39 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/* Copyright (c) 2019 Facebook */
copy-and-paste left-over...
> diff --git a/tools/testing/selftests/bpf/progs/bpf_smc.c b/tools/testing/selftests/bpf/progs/bpf_smc.c
> new file mode 100644
> index 0000000..78c7976
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/progs/bpf_smc.c
> @@ -0,0 +1,315 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +
> +#include <linux/bpf.h>
> +#include <linux/stddef.h>
> +#include <linux/smc.h>
> +#include <stdbool.h>
> +#include <linux/types.h>
> +#include <bpf/bpf_helpers.h>
> +#include <bpf/bpf_core_read.h>
> +#include <bpf/bpf_tracing.h>
> +
> +#define BPF_STRUCT_OPS(name, args...) \
> + SEC("struct_ops/"#name) \
> + BPF_PROG(name, args)
> +
> +#define SMC_LISTEN (10)
> +#define SMC_SOCK_CLOSED_TIMING (0)
> +extern unsigned long CONFIG_HZ __kconfig;
> +#define HZ CONFIG_HZ
> +
> +char _license[] SEC("license") = "GPL";
> +#define max(a, b) ((a) > (b) ? (a) : (b))
> +
> +struct sock_common {
> + unsigned char skc_state;
> + __u16 skc_num;
> +} __attribute__((preserve_access_index));
> +
> +struct sock {
> + struct sock_common __sk_common;
> + int sk_sndbuf;
> +} __attribute__((preserve_access_index));
> +
> +struct inet_sock {
> + struct sock sk;
> +} __attribute__((preserve_access_index));
> +
> +struct inet_connection_sock {
> + struct inet_sock icsk_inet;
> +} __attribute__((preserve_access_index));
> +
> +struct tcp_sock {
> + struct inet_connection_sock inet_conn;
> + __u32 rcv_nxt;
> + __u32 snd_nxt;
> + __u32 snd_una;
> + __u32 delivered;
> + __u8 syn_data:1, /* SYN includes data */
> + syn_fastopen:1, /* SYN includes Fast Open option */
> + syn_fastopen_exp:1,/* SYN includes Fast Open exp. option */
> + syn_fastopen_ch:1, /* Active TFO re-enabling probe */
> + syn_data_acked:1,/* data in SYN is acked by SYN-ACK */
> + save_syn:1, /* Save headers of SYN packet */
> + is_cwnd_limited:1,/* forward progress limited by snd_cwnd? */
> + syn_smc:1; /* SYN includes SMC */
> +} __attribute__((preserve_access_index));
> +
> +struct socket {
> + struct sock *sk;
> +} __attribute__((preserve_access_index));
All these tcp_sock, socket, inet_sock definitions can go away if it includes
"vmlinux.h". tcp_ca_write_sk_pacing.c is a better example to follow. Try to
define the "common" (eg. tcp, tc...etc) missing macros in bpf_tracing_net.h. The
smc specific macros can stay in this file.
> +static inline struct smc_prediction *smc_prediction_get(const struct smc_sock *smc,
> + const struct tcp_sock *tp, __u64 tstamp)
> +{
> + struct smc_prediction zero = {}, *smc_predictor;
> + __u16 key;
> + __u32 gap;
> + int err;
> +
> + err = bpf_core_read(&key, sizeof(__u16), &tp->inet_conn.icsk_inet.sk.__sk_common.skc_num);
> + if (err)
> + return NULL;
> +
> + /* BAD key */
> + if (key == 0)
> + return NULL;
> +
> + smc_predictor = bpf_map_lookup_elem(&negotiator_map, &key);
> + if (!smc_predictor) {
> + zero.start_tstamp = bpf_jiffies64();
> + zero.pacing_delta = SMC_PREDICTION_MIN_PACING_DELTA;
> + bpf_map_update_elem(&negotiator_map, &key, &zero, 0);
> + smc_predictor = bpf_map_lookup_elem(&negotiator_map, &key);
> + if (!smc_predictor)
> + return NULL;
> + }
> +
> + if (tstamp) {
> + bpf_spin_lock(&smc_predictor->lock);
> + gap = (tstamp - smc_predictor->start_tstamp) / smc_predictor->pacing_delta;
> + /* new splice */
> + if (gap > 0) {
> + smc_predictor->start_tstamp = tstamp;
> + smc_predictor->last_rate_of_lcc =
> + (smc_prediction_calt_rate(smc_predictor) * 7) >> (2 + gap);
> + smc_predictor->closed_long_cc = 0;
> + smc_predictor->closed_total_cc = 0;
> + smc_predictor->incoming_long_cc = 0;
> + }
> + bpf_spin_unlock(&smc_predictor->lock);
> + }
> + return smc_predictor;
> +}
> +
> +/* BPF struct ops for smc protocol negotiator */
> +struct smc_sock_negotiator_ops {
> + /* ret for negotiate */
> + int (*negotiate)(struct smc_sock *smc);
> +
> + /* info gathering timing */
> + void (*collect_info)(struct smc_sock *smc, int timing);
> +};
> +
> +int BPF_STRUCT_OPS(bpf_smc_negotiate, struct smc_sock *smc)
> +{
> + struct smc_prediction *smc_predictor;
> + struct tcp_sock *tp;
> + struct sock *clcsk;
> + int ret = SK_DROP;
> + __u32 rate = 0;
> +
> + /* Only make decison during listen */
> + if (smc->sk.__sk_common.skc_state != SMC_LISTEN)
> + return SK_PASS;
> +
> + clcsk = BPF_CORE_READ(smc, clcsock, sk);
Instead of using bpf_core_read here, why not directly gets the clcsk like the
'smc->sk.__sk_common.skc_state' above.
> + if (!clcsk)
> + goto error;
> +
> + tp = tcp_sk(clcsk);
There is a bpf_skc_to_tcp_sock(). Give it a try after changing the above
BPF_CORE_READ.
> + if (!tp)
> + goto error;
> +
> + smc_predictor = smc_prediction_get(smc, tp, bpf_jiffies64());
> + if (!smc_predictor)
> + return SK_PASS;
> +
> + bpf_spin_lock(&smc_predictor->lock);
> +
> + if (smc_predictor->incoming_long_cc == 0)
> + goto out_locked_pass;
> +
> + if (smc_predictor->incoming_long_cc > SMC_PREDICTION_MAX_LONGCC_PER_SPLICE) {
> + ret = 100;
> + goto out_locked_drop;
> + }
> +
> + rate = smc_prediction_calt_rate(smc_predictor);
> + if (rate < SMC_PREDICTION_LONGCC_RATE_THRESHOLD) {
> + ret = 200;
> + goto out_locked_drop;
> + }
> +out_locked_pass:
> + smc_predictor->incoming_long_cc++;
> + bpf_spin_unlock(&smc_predictor->lock);
> + return SK_PASS;
> +out_locked_drop:
> + bpf_spin_unlock(&smc_predictor->lock);
> +error:
> + return SK_DROP;
> +}
> +
> +void BPF_STRUCT_OPS(bpf_smc_collect_info, struct smc_sock *smc, int timing)
Try to stay with SEC("struct_ops/...") void BPF_PROG(....)
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