netdev - [RFC PATCH bpf-next 11/12] bpf: net: Add a qdisc kfunc to set sk_pacing

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Message-ID: <20250418224652.105998-12-martin.lau@linux.dev>
Date: Fri, 18 Apr 2025 15:46:49 -0700
From: Martin KaFai Lau <martin.lau@...ux.dev>
To: bpf@...r.kernel.org
Cc: 'Alexei Starovoitov ' <ast@...nel.org>,
	'Andrii Nakryiko ' <andrii@...nel.org>,
	'Daniel Borkmann ' <daniel@...earbox.net>,
	netdev@...r.kernel.org,
	kernel-team@...a.com,
	'Amery Hung ' <ameryhung@...il.com>
Subject: [RFC PATCH bpf-next 11/12] bpf: net: Add a qdisc kfunc to set sk_pacing_status.

From: Martin KaFai Lau <martin.lau@...nel.org>

bpf_qdisc_set_sk_pacing() is added to set the sk_pacing_status. This
can tell the tcp stack that the qdisc can do pacing and the tcp
stack does not need to do its own internal pacing.

It is only allowed in the enqueue ops.

Signed-off-by: Martin KaFai Lau <martin.lau@...nel.org>
---
 net/sched/bpf_qdisc.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/net/sched/bpf_qdisc.c b/net/sched/bpf_qdisc.c
index 9f32b305636f..45776918efcf 100644
--- a/net/sched/bpf_qdisc.c
+++ b/net/sched/bpf_qdisc.c
@@ -7,6 +7,7 @@
 #include <linux/filter.h>
 #include <net/pkt_sched.h>
 #include <net/pkt_cls.h>
+#include <net/sock.h>
 
 #define QDISC_OP_IDX(op)	(offsetof(struct Qdisc_ops, op) / sizeof(void (*)(void)))
 #define QDISC_MOFF_IDX(moff)	(moff / sizeof(void (*)(void)))
@@ -214,6 +215,17 @@ __bpf_kfunc void bpf_qdisc_skb_drop(struct sk_buff *skb,
 	__qdisc_drop(skb, (struct sk_buff **)to_free_list);
 }
 
+__bpf_kfunc int bpf_qdisc_set_sk_pacing(struct sk_buff *skb, enum sk_pacing pacing)
+{
+	struct sock *sk = skb->sk;
+
+	if (!sk || sk_listener_or_tw(sk) || pacing != SK_PACING_FQ)
+		return -EINVAL;
+
+	smp_store_release(&sk->sk_pacing_status, pacing);
+	return 0;
+}
+
 /* 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.
@@ -274,6 +286,7 @@ BTF_KFUNCS_START(qdisc_kfunc_ids)
 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_qdisc_set_sk_pacing, KF_TRUSTED_ARGS)
 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)
@@ -290,6 +303,7 @@ 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_ID(func, bpf_qdisc_set_sk_pacing)
 BTF_SET_END(qdisc_enqueue_kfunc_set)
 
 BTF_SET_START(qdisc_dequeue_kfunc_set)
-- 
2.47.1