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Sat, 19 Sep 2026 07:39:09 -0700 (PDT) Received: from KERNELXING-MC1.tencent.com ([43.132.141.21]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2ddc179ed79sm10711715ad.43.2026.09.19.07.39.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 19 Sep 2026 07:39:08 -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 6/9] bpf-timestamping: restore skb hwtstamp if it is used by start time Date: Sat, 19 Sep 2026 22:37:29 +0800 Message-Id: <20260919143732.11772-7-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 When BPF Timestamping V1 (SKBTX_BPF) and V2 are both active, skb_tstamp_tx_report_bpf_timestamping() writes the hardware timestamp into orig_skb: *skb_hwtstamps(skb) = *hwtstamps; Since orig_skb shares skb_shared_info with the retransmit-queue original via skb_clone(), this clobbers V2's start_time on the retransmit-queue skb. Save start_time before the write and restore it after the V1 callback returns, so both timestamping generations can coexist. Signed-off-by: Jason Xing --- net/core/skbuff.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 44aeea713da7..98cd813006b8 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -5686,6 +5686,7 @@ static void skb_tstamp_tx_report_bpf_timestamping(struct sk_buff *skb, struct sock *sk, int tstype) { + ktime_t start = 0; int op; switch (tstype) { @@ -5695,6 +5696,8 @@ static void skb_tstamp_tx_report_bpf_timestamping(struct sk_buff *skb, case SCM_TSTAMP_SND: if (hwtstamps) { op = BPF_SOCK_OPS_TSTAMP_SND_HW_CB; + if (static_branch_unlikely(&bpfts_v2_needed_key)) + start = skb_hwtstamps(skb)->start_time; *skb_hwtstamps(skb) = *hwtstamps; } else { op = BPF_SOCK_OPS_TSTAMP_SND_SW_CB; @@ -5708,6 +5711,8 @@ static void skb_tstamp_tx_report_bpf_timestamping(struct sk_buff *skb, } bpf_skops_tx_timestamping(sk, skb, op); + if (static_branch_unlikely(&bpfts_v2_needed_key) && start) + skb_hwtstamps(skb)->start_time = start; } void __skb_tstamp_tx(struct sk_buff *orig_skb, -- 2.43.7