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Mon, 20 May 2024 20:15:06 -0700 (PDT) Date: Mon, 20 May 2024 20:15:04 -0700 In-Reply-To: <20240510192412.3297104-18-amery.hung@bytedance.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20240510192412.3297104-1-amery.hung@bytedance.com> <20240510192412.3297104-18-amery.hung@bytedance.com> Message-ID: Subject: Re: [RFC PATCH v8 17/20] selftests: Add a basic fifo qdisc test From: Stanislav Fomichev To: Amery Hung Cc: netdev@vger.kernel.org, bpf@vger.kernel.org, yangpeihao@sjtu.edu.cn, daniel@iogearbox.net, andrii@kernel.org, martin.lau@kernel.org, sinquersw@gmail.com, toke@redhat.com, jhs@mojatatu.com, jiri@resnulli.us, xiyou.wangcong@gmail.com, yepeilin.cs@gmail.com Content-Type: text/plain; charset="utf-8" On 05/10, Amery Hung wrote: > This selftest shows a bare minimum fifo qdisc, which simply enqueues skbs > into the back of a bpf list and dequeues from the front of the list. > > Signed-off-by: Amery Hung > --- > .../selftests/bpf/prog_tests/bpf_qdisc.c | 161 ++++++++++++++++++ > .../selftests/bpf/progs/bpf_qdisc_common.h | 23 +++ > .../selftests/bpf/progs/bpf_qdisc_fifo.c | 83 +++++++++ > 3 files changed, 267 insertions(+) > create mode 100644 tools/testing/selftests/bpf/prog_tests/bpf_qdisc.c > create mode 100644 tools/testing/selftests/bpf/progs/bpf_qdisc_common.h > create mode 100644 tools/testing/selftests/bpf/progs/bpf_qdisc_fifo.c > > diff --git a/tools/testing/selftests/bpf/prog_tests/bpf_qdisc.c b/tools/testing/selftests/bpf/prog_tests/bpf_qdisc.c > new file mode 100644 > index 000000000000..295d0216e70f > --- /dev/null > +++ b/tools/testing/selftests/bpf/prog_tests/bpf_qdisc.c > @@ -0,0 +1,161 @@ > +#include > +#include > +#include > + > +#include "network_helpers.h" > +#include "bpf_qdisc_fifo.skel.h" > + > +#ifndef ENOTSUPP > +#define ENOTSUPP 524 > +#endif > + > +#define LO_IFINDEX 1 > + > +static const unsigned int total_bytes = 10 * 1024 * 1024; > +static int stop; > + > +static void *server(void *arg) > +{ > + int lfd = (int)(long)arg, err = 0, fd; > + ssize_t nr_sent = 0, bytes = 0; > + char batch[1500]; > + > + fd = accept(lfd, NULL, NULL); > + while (fd == -1) { > + if (errno == EINTR) > + continue; > + err = -errno; > + goto done; > + } > + > + if (settimeo(fd, 0)) { > + err = -errno; > + goto done; > + } > + > + while (bytes < total_bytes && !READ_ONCE(stop)) { > + nr_sent = send(fd, &batch, > + MIN(total_bytes - bytes, sizeof(batch)), 0); > + if (nr_sent == -1 && errno == EINTR) > + continue; > + if (nr_sent == -1) { > + err = -errno; > + break; > + } > + bytes += nr_sent; > + } > + > + ASSERT_EQ(bytes, total_bytes, "send"); > + > +done: > + if (fd >= 0) > + close(fd); > + if (err) { > + WRITE_ONCE(stop, 1); > + return ERR_PTR(err); > + } > + return NULL; > +} > + > +static void do_test(char *qdisc) > +{ > + DECLARE_LIBBPF_OPTS(bpf_tc_hook, hook, .ifindex = LO_IFINDEX, > + .attach_point = BPF_TC_QDISC, > + .parent = TC_H_ROOT, > + .handle = 0x8000000, > + .qdisc = qdisc); > + struct sockaddr_in6 sa6 = {}; > + ssize_t nr_recv = 0, bytes = 0; > + int lfd = -1, fd = -1; > + pthread_t srv_thread; > + socklen_t addrlen = sizeof(sa6); > + void *thread_ret; > + char batch[1500]; > + int err; > + > + WRITE_ONCE(stop, 0); > + > + err = bpf_tc_hook_create(&hook); > + if (!ASSERT_OK(err, "attach qdisc")) > + return; > + > + lfd = start_server(AF_INET6, SOCK_STREAM, NULL, 0, 0); > + if (!ASSERT_NEQ(lfd, -1, "socket")) { > + bpf_tc_hook_destroy(&hook); > + return; > + } > + > + fd = socket(AF_INET6, SOCK_STREAM, 0); > + if (!ASSERT_NEQ(fd, -1, "socket")) { > + bpf_tc_hook_destroy(&hook); > + close(lfd); > + return; > + } > + > + if (settimeo(lfd, 0) || settimeo(fd, 0)) > + goto done; > + > + err = getsockname(lfd, (struct sockaddr *)&sa6, &addrlen); > + if (!ASSERT_NEQ(err, -1, "getsockname")) > + goto done; > + > + /* connect to server */ > + err = connect(fd, (struct sockaddr *)&sa6, addrlen); > + if (!ASSERT_NEQ(err, -1, "connect")) > + goto done; > + > + err = pthread_create(&srv_thread, NULL, server, (void *)(long)lfd); > + if (!ASSERT_OK(err, "pthread_create")) > + goto done; > + > + /* recv total_bytes */ > + while (bytes < total_bytes && !READ_ONCE(stop)) { > + nr_recv = recv(fd, &batch, > + MIN(total_bytes - bytes, sizeof(batch)), 0); > + if (nr_recv == -1 && errno == EINTR) > + continue; > + if (nr_recv == -1) > + break; > + bytes += nr_recv; > + } > + > + ASSERT_EQ(bytes, total_bytes, "recv"); > + > + WRITE_ONCE(stop, 1); > + pthread_join(srv_thread, &thread_ret); > + ASSERT_OK(IS_ERR(thread_ret), "thread_ret"); > + > +done: > + close(lfd); > + close(fd); > + > + bpf_tc_hook_destroy(&hook); > + return; > +} > + > +static void test_fifo(void) > +{ > + struct bpf_qdisc_fifo *fifo_skel; > + struct bpf_link *link; > + > + fifo_skel = bpf_qdisc_fifo__open_and_load(); > + if (!ASSERT_OK_PTR(fifo_skel, "bpf_qdisc_fifo__open_and_load")) > + return; > + > + link = bpf_map__attach_struct_ops(fifo_skel->maps.fifo); > + if (!ASSERT_OK_PTR(link, "bpf_map__attach_struct_ops")) { > + bpf_qdisc_fifo__destroy(fifo_skel); > + return; > + } > + > + do_test("bpf_fifo"); > + > + bpf_link__destroy(link); > + bpf_qdisc_fifo__destroy(fifo_skel); > +} > + > +void test_bpf_qdisc(void) > +{ > + if (test__start_subtest("fifo")) > + test_fifo(); > +} > diff --git a/tools/testing/selftests/bpf/progs/bpf_qdisc_common.h b/tools/testing/selftests/bpf/progs/bpf_qdisc_common.h > new file mode 100644 > index 000000000000..96ab357de28e > --- /dev/null > +++ b/tools/testing/selftests/bpf/progs/bpf_qdisc_common.h > @@ -0,0 +1,23 @@ > +#ifndef _BPF_QDISC_COMMON_H > +#define _BPF_QDISC_COMMON_H > + > +#define NET_XMIT_SUCCESS 0x00 > +#define NET_XMIT_DROP 0x01 /* skb dropped */ > +#define NET_XMIT_CN 0x02 /* congestion notification */ > + > +#define TC_PRIO_CONTROL 7 > +#define TC_PRIO_MAX 15 > + > +void bpf_skb_set_dev(struct sk_buff *skb, struct Qdisc *sch) __ksym; > +u32 bpf_skb_get_hash(struct sk_buff *p) __ksym; > +void bpf_skb_release(struct sk_buff *p) __ksym; > +void bpf_qdisc_skb_drop(struct sk_buff *p, struct bpf_sk_buff_ptr *to_free) __ksym; > +void bpf_qdisc_watchdog_schedule(struct Qdisc *sch, u64 expire, u64 delta_ns) __ksym; > +bool bpf_qdisc_find_class(struct Qdisc *sch, u32 classid) __ksym; > +int bpf_qdisc_create_child(struct Qdisc *sch, u32 min, > + struct netlink_ext_ack *extack) __ksym; > +int bpf_qdisc_enqueue(struct sk_buff *skb, struct Qdisc *sch, u32 classid, > + struct bpf_sk_buff_ptr *to_free_list) __ksym; > +struct sk_buff *bpf_qdisc_dequeue(struct Qdisc *sch, u32 classid) __ksym; > + > +#endif > diff --git a/tools/testing/selftests/bpf/progs/bpf_qdisc_fifo.c b/tools/testing/selftests/bpf/progs/bpf_qdisc_fifo.c > new file mode 100644 > index 000000000000..433fd9c3639c > --- /dev/null > +++ b/tools/testing/selftests/bpf/progs/bpf_qdisc_fifo.c > @@ -0,0 +1,83 @@ > +#include > +#include "bpf_experimental.h" > +#include "bpf_qdisc_common.h" > + > +char _license[] SEC("license") = "GPL"; > + > +#define private(name) SEC(".data." #name) __hidden __attribute__((aligned(8))) > + > +private(B) struct bpf_spin_lock q_fifo_lock; > +private(B) struct bpf_list_head q_fifo __contains_kptr(sk_buff, bpf_list); > + > +unsigned int q_limit = 1000; > +unsigned int q_qlen = 0; > + > +SEC("struct_ops/bpf_fifo_enqueue") > +int BPF_PROG(bpf_fifo_enqueue, struct sk_buff *skb, struct Qdisc *sch, > + struct bpf_sk_buff_ptr *to_free) > +{ > + q_qlen++; > + if (q_qlen > q_limit) { > + bpf_qdisc_skb_drop(skb, to_free); > + return NET_XMIT_DROP; > + } [..] > + bpf_spin_lock(&q_fifo_lock); > + bpf_list_excl_push_back(&q_fifo, &skb->bpf_list); > + bpf_spin_unlock(&q_fifo_lock); Can you also expand a bit on the locking here and elsewhere? And how it interplays with TCQ_F_NOLOCK? As I mentioned at lsfmmbpf, I don't think there is a lot of similar locking in the existing C implementations? So why do we need it here?