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[76.146.13.146]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-2fa3fb55dcasm5554961a91.4.2025.02.10.09.43.58 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 10 Feb 2025 09:43:59 -0800 (PST) From: Amery Hung To: netdev@vger.kernel.org Cc: bpf@vger.kernel.org, daniel@iogearbox.net, andrii@kernel.org, alexei.starovoitov@gmail.com, martin.lau@kernel.org, kuba@kernel.org, edumazet@google.com, xiyou.wangcong@gmail.com, cong.wang@bytedance.com, jhs@mojatatu.com, sinquersw@gmail.com, toke@redhat.com, jiri@resnulli.us, stfomichev@gmail.com, ekarani.silvestre@ccc.ufcg.edu.br, yangpeihao@sjtu.edu.cn, yepeilin.cs@gmail.com, ameryhung@gmail.com, kernel-team@meta.com Subject: [PATCH bpf-next v4 11/19] bpf: net_sched: Add a qdisc watchdog timer Date: Mon, 10 Feb 2025 09:43:25 -0800 Message-ID: <20250210174336.2024258-12-ameryhung@gmail.com> X-Mailer: git-send-email 2.47.1 In-Reply-To: <20250210174336.2024258-1-ameryhung@gmail.com> References: <20250210174336.2024258-1-ameryhung@gmail.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Amery Hung Add a watchdog timer to bpf qdisc. The watchdog can be used to schedule the execution of qdisc through kfunc, bpf_qdisc_schedule(). It can be useful for building traffic shaping scheduling algorithm, where the time the next packet will be dequeued is known. Signed-off-by: Amery Hung --- include/linux/filter.h | 10 +++++ net/sched/bpf_qdisc.c | 92 ++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 102 insertions(+) diff --git a/include/linux/filter.h b/include/linux/filter.h index a3ea46281595..3ed6eb9e7c73 100644 --- a/include/linux/filter.h +++ b/include/linux/filter.h @@ -469,6 +469,16 @@ static inline bool insn_is_cast_user(const struct bpf_insn *insn) .off = 0, \ .imm = BPF_CALL_IMM(FUNC) }) +/* Kfunc call */ + +#define BPF_CALL_KFUNC(OFF, IMM) \ + ((struct bpf_insn) { \ + .code = BPF_JMP | BPF_CALL, \ + .dst_reg = 0, \ + .src_reg = BPF_PSEUDO_KFUNC_CALL, \ + .off = OFF, \ + .imm = IMM }) + /* Raw code statement block */ #define BPF_RAW_INSN(CODE, DST, SRC, OFF, IMM) \ diff --git a/net/sched/bpf_qdisc.c b/net/sched/bpf_qdisc.c index 69a1d547390c..ae06637f4bab 100644 --- a/net/sched/bpf_qdisc.c +++ b/net/sched/bpf_qdisc.c @@ -8,6 +8,10 @@ static struct bpf_struct_ops bpf_Qdisc_ops; +struct bpf_sched_data { + struct qdisc_watchdog watchdog; +}; + struct bpf_sk_buff_ptr { struct sk_buff *skb; }; @@ -111,6 +115,46 @@ static int bpf_qdisc_btf_struct_access(struct bpf_verifier_log *log, return 0; } +BTF_ID_LIST(bpf_qdisc_init_prologue_ids) +BTF_ID(func, bpf_qdisc_init_prologue) + +static int bpf_qdisc_gen_prologue(struct bpf_insn *insn_buf, bool direct_write, + const struct bpf_prog *prog) +{ + struct bpf_insn *insn = insn_buf; + + if (bpf_struct_ops_prog_moff(prog) != offsetof(struct Qdisc_ops, init)) + return 0; + + *insn++ = BPF_MOV64_REG(BPF_REG_6, BPF_REG_1); + *insn++ = BPF_LDX_MEM(BPF_DW, BPF_REG_1, BPF_REG_1, 0); + *insn++ = BPF_CALL_KFUNC(0, bpf_qdisc_init_prologue_ids[0]); + *insn++ = BPF_MOV64_REG(BPF_REG_1, BPF_REG_6); + *insn++ = prog->insnsi[0]; + + return insn - insn_buf; +} + +BTF_ID_LIST(bpf_qdisc_reset_destroy_epilogue_ids) +BTF_ID(func, bpf_qdisc_reset_destroy_epilogue) + +static int bpf_qdisc_gen_epilogue(struct bpf_insn *insn_buf, const struct bpf_prog *prog, + s16 ctx_stack_off) +{ + struct bpf_insn *insn = insn_buf; + + if (bpf_struct_ops_prog_moff(prog) != offsetof(struct Qdisc_ops, reset) && + bpf_struct_ops_prog_moff(prog) != offsetof(struct Qdisc_ops, destroy)) + return 0; + + *insn++ = BPF_LDX_MEM(BPF_DW, BPF_REG_1, BPF_REG_FP, ctx_stack_off); + *insn++ = BPF_LDX_MEM(BPF_DW, BPF_REG_1, BPF_REG_1, 0); + *insn++ = BPF_CALL_KFUNC(0, bpf_qdisc_reset_destroy_epilogue_ids[0]); + *insn++ = BPF_EXIT_INSN(); + + return insn - insn_buf; +} + __bpf_kfunc_start_defs(); /* bpf_skb_get_hash - Get the flow hash of an skb. @@ -139,6 +183,36 @@ __bpf_kfunc void bpf_qdisc_skb_drop(struct sk_buff *skb, __qdisc_drop(skb, (struct sk_buff **)to_free_list); } +/* bpf_qdisc_watchdog_schedule - Schedule a qdisc to a later time using a timer. + * @sch: The qdisc to be scheduled. + * @expire: The expiry time of the timer. + * @delta_ns: The slack range of the timer. + */ +__bpf_kfunc void bpf_qdisc_watchdog_schedule(struct Qdisc *sch, u64 expire, u64 delta_ns) +{ + struct bpf_sched_data *q = qdisc_priv(sch); + + qdisc_watchdog_schedule_range_ns(&q->watchdog, expire, delta_ns); +} + +/* bpf_qdisc_init_prologue - Hidden kfunc called in prologue of .init. */ +__bpf_kfunc void bpf_qdisc_init_prologue(struct Qdisc *sch) +{ + struct bpf_sched_data *q = qdisc_priv(sch); + + qdisc_watchdog_init(&q->watchdog, sch); +} + +/* bpf_qdisc_reset_destroy_epilogue - Hidden kfunc called in epilogue of .reset + * and .destroy + */ +__bpf_kfunc void bpf_qdisc_reset_destroy_epilogue(struct Qdisc *sch) +{ + struct bpf_sched_data *q = qdisc_priv(sch); + + qdisc_watchdog_cancel(&q->watchdog); +} + __bpf_kfunc_end_defs(); BTF_KFUNCS_START(qdisc_kfunc_ids) @@ -146,6 +220,9 @@ BTF_ID_FLAGS(func, bpf_skb_get_hash, KF_TRUSTED_ARGS) BTF_ID_FLAGS(func, bpf_kfree_skb, KF_RELEASE) BTF_ID_FLAGS(func, bpf_qdisc_skb_drop, KF_RELEASE) BTF_ID_FLAGS(func, bpf_dynptr_from_skb, KF_TRUSTED_ARGS) +BTF_ID_FLAGS(func, bpf_qdisc_watchdog_schedule, KF_TRUSTED_ARGS) +BTF_ID_FLAGS(func, bpf_qdisc_init_prologue, KF_TRUSTED_ARGS) +BTF_ID_FLAGS(func, bpf_qdisc_reset_destroy_epilogue, KF_TRUSTED_ARGS) BTF_KFUNCS_END(qdisc_kfunc_ids) BTF_SET_START(qdisc_common_kfunc_set) @@ -156,8 +233,13 @@ BTF_SET_END(qdisc_common_kfunc_set) BTF_SET_START(qdisc_enqueue_kfunc_set) BTF_ID(func, bpf_qdisc_skb_drop) +BTF_ID(func, bpf_qdisc_watchdog_schedule) BTF_SET_END(qdisc_enqueue_kfunc_set) +BTF_SET_START(qdisc_dequeue_kfunc_set) +BTF_ID(func, bpf_qdisc_watchdog_schedule) +BTF_SET_END(qdisc_dequeue_kfunc_set) + static int bpf_qdisc_kfunc_filter(const struct bpf_prog *prog, u32 kfunc_id) { if (bpf_Qdisc_ops.type != btf_type_by_id(prog->aux->attach_btf, @@ -174,6 +256,9 @@ static int bpf_qdisc_kfunc_filter(const struct bpf_prog *prog, u32 kfunc_id) if (bpf_struct_ops_prog_moff(prog) == offsetof(struct Qdisc_ops, enqueue)) { if (btf_id_set_contains(&qdisc_enqueue_kfunc_set, kfunc_id)) return 0; + } else if (bpf_struct_ops_prog_moff(prog) == offsetof(struct Qdisc_ops, dequeue)) { + if (btf_id_set_contains(&qdisc_dequeue_kfunc_set, kfunc_id)) + return 0; } return btf_id_set_contains(&qdisc_common_kfunc_set, kfunc_id) ? 0 : -EACCES; @@ -189,6 +274,8 @@ static const struct bpf_verifier_ops bpf_qdisc_verifier_ops = { .get_func_proto = bpf_qdisc_get_func_proto, .is_valid_access = bpf_qdisc_is_valid_access, .btf_struct_access = bpf_qdisc_btf_struct_access, + .gen_prologue = bpf_qdisc_gen_prologue, + .gen_epilogue = bpf_qdisc_gen_epilogue, }; static int bpf_qdisc_init_member(const struct btf_type *t, @@ -204,6 +291,11 @@ static int bpf_qdisc_init_member(const struct btf_type *t, moff = __btf_member_bit_offset(t, member) / 8; switch (moff) { + case offsetof(struct Qdisc_ops, priv_size): + if (uqdisc_ops->priv_size) + return -EINVAL; + qdisc_ops->priv_size = sizeof(struct bpf_sched_data); + return 1; case offsetof(struct Qdisc_ops, peek): qdisc_ops->peek = qdisc_peek_dequeued; return 0; -- 2.47.1