From: Amery Hung <ameryhung@gmail.com>
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,
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 v5 05/13] bpf: net_sched: Add a qdisc watchdog timer
Date: Thu, 13 Mar 2025 12:02:59 -0700 [thread overview]
Message-ID: <20250313190309.2545711-6-ameryhung@gmail.com> (raw)
In-Reply-To: <20250313190309.2545711-1-ameryhung@gmail.com>
From: Amery Hung <amery.hung@bytedance.com>
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 <amery.hung@bytedance.com>
---
net/sched/bpf_qdisc.c | 92 +++++++++++++++++++++++++++++++++++++++++++
1 file changed, 92 insertions(+)
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
next prev parent reply other threads:[~2025-03-13 19:03 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-03-13 19:02 [PATCH bpf-next v5 00/13] bpf qdisc Amery Hung
2025-03-13 19:02 ` [PATCH bpf-next v5 01/13] bpf: Prepare to reuse get_ctx_arg_idx Amery Hung
2025-03-13 19:02 ` [PATCH bpf-next v5 02/13] bpf: Generalize finding member offset of struct_ops prog Amery Hung
2025-03-13 19:02 ` [PATCH bpf-next v5 03/13] bpf: net_sched: Support implementation of Qdisc_ops in bpf Amery Hung
2025-03-13 19:02 ` [PATCH bpf-next v5 04/13] bpf: net_sched: Add basic bpf qdisc kfuncs Amery Hung
2025-03-14 20:14 ` Alexei Starovoitov
2025-03-17 19:44 ` Amery Hung
2025-03-13 19:02 ` Amery Hung [this message]
2025-03-13 19:03 ` [PATCH bpf-next v5 06/13] bpf: net_sched: Support updating bstats Amery Hung
2025-03-13 19:03 ` [PATCH bpf-next v5 07/13] bpf: net_sched: Support updating qstats Amery Hung
2025-03-14 20:24 ` Alexei Starovoitov
2025-03-16 13:56 ` Amery Hung
2025-03-13 19:03 ` [PATCH bpf-next v5 08/13] bpf: net_sched: Allow writing to more Qdisc members Amery Hung
2025-03-13 19:03 ` [PATCH bpf-next v5 09/13] bpf: net_sched: Disable attaching bpf qdisc to non root Amery Hung
2025-03-14 20:31 ` Alexei Starovoitov
2025-03-16 13:58 ` Amery Hung
2025-03-13 19:03 ` [PATCH bpf-next v5 10/13] libbpf: Support creating and destroying qdisc Amery Hung
2025-03-13 19:03 ` [PATCH bpf-next v5 11/13] selftests/bpf: Add a basic fifo qdisc test Amery Hung
2025-03-13 19:03 ` [PATCH bpf-next v5 12/13] selftests/bpf: Add a bpf fq qdisc to selftest Amery Hung
2025-03-14 20:35 ` Alexei Starovoitov
2025-03-17 1:25 ` Amery Hung
2025-03-13 19:03 ` [PATCH bpf-next v5 13/13] selftests/bpf: Test attaching bpf qdisc to mq and non root Amery Hung
2025-03-13 19:52 ` [PATCH bpf-next v5 00/13] bpf qdisc Toke Høiland-Jørgensen
2025-03-14 1:43 ` Amery Hung
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