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Sat, 19 Sep 2026 07:38:50 -0700 (PDT) Received: from KERNELXING-MC1.tencent.com ([43.132.141.21]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2ddc179ed79sm10711715ad.43.2026.09.19.07.38.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 19 Sep 2026 07:38:49 -0700 (PDT) From: Jason Xing To: davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, horms@kernel.org, willemb@google.com, kuniyu@google.com Cc: netdev@vger.kernel.org, bpf@vger.kernel.org, Jason Xing Subject: [PATCH RFC net-next 1/9] net: add bpf_setsockopt for SK_BPF_CB_TIMESTAMPING_V2 Date: Sat, 19 Sep 2026 22:37:24 +0800 Message-Id: <20260919143732.11772-2-kerneljasonxing@gmail.com> X-Mailer: git-send-email 2.33.0 In-Reply-To: <20260919143732.11772-1-kerneljasonxing@gmail.com> References: <20260919143732.11772-1-kerneljasonxing@gmail.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Introduce a per-socket bit SK_BPF_CB_TIMESTAMPING_V2 for BPF Timestamping V2, that allows a socket opt into recording a "start time" on every skb it produces or receives, which should be reflected in the rest of patches. Add a static key to avoid normal traffic suffered from the performance affect. It works exactly like netstamp_needed_key. Use bpf_setsockopt(SK_BPF_CB_FLAGS) to toggle the feature that is the same mechanism used by SK_BPF_CB_TX_TIMESTAMPING which is actually version 1. The whole feature is only reachable from BPF, not from user-space setsockopt(). Signed-off-by: Jason Xing --- include/linux/skbuff.h | 4 +++ include/uapi/linux/bpf.h | 5 ++-- net/core/dev.c | 53 ++++++++++++++++++++++++++++++++++ net/core/filter.c | 7 +++++ net/core/sock.c | 5 ++++ tools/include/uapi/linux/bpf.h | 5 ++-- 6 files changed, 75 insertions(+), 4 deletions(-) diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index 671c13494566..55ae1653a1cf 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -4514,6 +4514,10 @@ static inline void skb_set_delivery_type_by_clockid(struct sk_buff *skb, DECLARE_STATIC_KEY_FALSE(netstamp_needed_key); +DECLARE_STATIC_KEY_FALSE(bpfts_v2_needed_key); +void bpfts_v2_enable(void); +void bpfts_v2_disable(void); + /* It is used in the ingress path to clear the delivery_time. * If needed, set the skb->tstamp to the (rcv) timestamp. */ diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 732b35cc08d1..40feea175a10 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -7143,8 +7143,9 @@ enum { enum { SK_BPF_CB_TX_TIMESTAMPING = 1<<0, - SK_BPF_CB_MASK = (SK_BPF_CB_TX_TIMESTAMPING - 1) | - SK_BPF_CB_TX_TIMESTAMPING + SK_BPF_CB_TIMESTAMPING_V2 = 1<<1, + SK_BPF_CB_MASK = (SK_BPF_CB_TIMESTAMPING_V2 - 1) | + SK_BPF_CB_TIMESTAMPING_V2 }; /* List of known BPF sock_ops operators. diff --git a/net/core/dev.c b/net/core/dev.c index 38336858c168..4479fc87b789 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -2440,6 +2440,59 @@ void net_disable_timestamp(void) } EXPORT_SYMBOL(net_disable_timestamp); +DEFINE_STATIC_KEY_FALSE(bpfts_v2_needed_key); +EXPORT_SYMBOL(bpfts_v2_needed_key); +#ifdef CONFIG_JUMP_LABEL +static atomic_t bpfts_v2_needed_deferred; +static atomic_t bpfts_v2_wanted; +static void bpfts_v2_clear(struct work_struct *work) +{ + int deferred = atomic_xchg(&bpfts_v2_needed_deferred, 0); + int wanted; + + wanted = atomic_add_return(deferred, &bpfts_v2_wanted); + if (wanted > 0) + static_branch_enable(&bpfts_v2_needed_key); + else + static_branch_disable(&bpfts_v2_needed_key); +} +static DECLARE_WORK(bpfts_v2_work, bpfts_v2_clear); +#endif + +void bpfts_v2_enable(void) +{ +#ifdef CONFIG_JUMP_LABEL + int wanted = atomic_read(&bpfts_v2_wanted); + + while (wanted > 0) { + if (atomic_try_cmpxchg(&bpfts_v2_wanted, &wanted, wanted + 1)) + return; + } + atomic_inc(&bpfts_v2_needed_deferred); + schedule_work(&bpfts_v2_work); +#else + static_branch_inc(&bpfts_v2_needed_key); +#endif +} +EXPORT_SYMBOL(bpfts_v2_enable); + +void bpfts_v2_disable(void) +{ +#ifdef CONFIG_JUMP_LABEL + int wanted = atomic_read(&bpfts_v2_wanted); + + while (wanted > 1) { + if (atomic_try_cmpxchg(&bpfts_v2_wanted, &wanted, wanted - 1)) + return; + } + atomic_dec(&bpfts_v2_needed_deferred); + schedule_work(&bpfts_v2_work); +#else + static_branch_dec(&bpfts_v2_needed_key); +#endif +} +EXPORT_SYMBOL(bpfts_v2_disable); + static inline void net_timestamp_set(struct sk_buff *skb) { skb->tstamp = 0; diff --git a/net/core/filter.c b/net/core/filter.c index 61940e753552..3486c5c2d170 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -5468,6 +5468,13 @@ static int sk_bpf_set_get_cb_flags(struct sock *sk, char *optval, bool getopt) if (sk_bpf_cb_flags & ~SK_BPF_CB_MASK) return -EINVAL; + if ((sk_bpf_cb_flags ^ sk->sk_bpf_cb_flags) & SK_BPF_CB_TIMESTAMPING_V2) { + if (sk_bpf_cb_flags & SK_BPF_CB_TIMESTAMPING_V2) + bpfts_v2_enable(); + else + bpfts_v2_disable(); + } + sk->sk_bpf_cb_flags = sk_bpf_cb_flags; return 0; diff --git a/net/core/sock.c b/net/core/sock.c index 1ad41904db25..251c88e2ee45 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -2364,6 +2364,9 @@ static void __sk_destruct(struct rcu_head *head) sock_disable_timestamp(sk, SK_FLAGS_TIMESTAMP); + if (sk->sk_bpf_cb_flags & SK_BPF_CB_TIMESTAMPING_V2) + bpfts_v2_disable(); + #ifdef CONFIG_BPF_SYSCALL bpf_sk_storage_free(sk); #endif @@ -2550,6 +2553,8 @@ struct sock *sk_clone(const struct sock *sk, const gfp_t priority, if (sock_needs_netstamp(sk) && newsk->sk_flags & SK_FLAGS_TIMESTAMP) net_enable_timestamp(); + if (newsk->sk_bpf_cb_flags & SK_BPF_CB_TIMESTAMPING_V2) + bpfts_v2_enable(); rcu_read_lock(); filter = rcu_dereference(sk->sk_filter); diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index 732b35cc08d1..40feea175a10 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -7143,8 +7143,9 @@ enum { enum { SK_BPF_CB_TX_TIMESTAMPING = 1<<0, - SK_BPF_CB_MASK = (SK_BPF_CB_TX_TIMESTAMPING - 1) | - SK_BPF_CB_TX_TIMESTAMPING + SK_BPF_CB_TIMESTAMPING_V2 = 1<<1, + SK_BPF_CB_MASK = (SK_BPF_CB_TIMESTAMPING_V2 - 1) | + SK_BPF_CB_TIMESTAMPING_V2 }; /* List of known BPF sock_ops operators. -- 2.43.7