From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mta0.migadu.com (out-241.mta0.migadu.com [91.218.175.241]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 98CD4595740 for ; Thu, 17 Sep 2026 14:09:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.241 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789654204; cv=none; b=kO96z3GRNZ2wPeC9aZQvro7U2mj1cYWJx7fBGe9sQ6yOiVNt8RmJHI/dGefbEuR4+Wezhm/ekkxKt22skP0QDmVo7LXZNYqq4rb5avIYWy1cqD2ON/yXHlqQ9sN2/tcKblU2KsLzO0A6iKptjb9bUyQ3ta8KWZQt/6aKOrAOUhI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789654204; c=relaxed/simple; bh=j8COZdqiLv/WW2hv05JO0I6ITBYjGwAy5SbXukZzWVI=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=nzZUdMBS8dD8+Oqotvhbh044SG/LelzwVCD0vJTqEnQzvv9CSYsQSPjxbZ6rmYowwiZTJUuT/NvELa0rg+g2cjnabKGdDO6wpzrh0+UEtSrOiyR7X8h+Bi+xOyWb4CoucOgFnjs7tjXOy5Br0yz/wUh1C0hfyRm0eZSMtQPTTaE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=rMawkcKJ; arc=none smtp.client-ip=91.218.175.241 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="rMawkcKJ" X-Envelope-To: netdev@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=j8COZdqiLv/WW2hv05JO0I6ITBYjGwAy5SbXukZzWVI=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1789654181; v=1; x=1790258981; b=rMawkcKJRvODysJZDvCLFpDFbhQ4r0K8Gb1cXDcQbzTe+0EsxQyFcl50FtpJA7MbwWeMwXIU nxExlIJM6Ss89tIT6WUgbwmfxDu1SmS5bf/g2bhTxkwrgOVljaNd7rB4mKcvkDuhrNUA+e/ODg1 SplUKpxBY7bAJWzv638/czec= X-Envelope-To: netdev@vger.kernel.org Received: by smtp.migadu.com with ESMTPS id afde411d107651f6; Thu, 17 Sep 2026 14:09:41 +0000 X-Mizu-Trace-ID: afde411d107651f6 X-Migadu-Flow: FLOW_OUT Message-ID: Date: Thu, 17 Sep 2026 22:09:32 +0800 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net v2] tcp: preserve timestamps across receive queue collapse To: Jason Xing Cc: netdev@vger.kernel.org, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, horms@kernel.org, willemb@google.com, kuniyu@google.com References: <20260917132742.87117-1-kerneljasonxing@gmail.com> From: Xuanqiang Luo In-Reply-To: <20260917132742.87117-1-kerneljasonxing@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit 在 2026/9/17 21:27, Jason Xing 写道: > When tcp_collapse() rebuilds skbs under memory pressure, the copy > process doesn't include the right tstamp and hwtstamp from the > old skb. And memcpy(nskb->cb, skb->cb, ...) copies has_rxtstamp, > but nskb->tstamp and hwtstamps are left at zero, so > tcp_recv_timestamp() ends up emitting no cmsg at all. > > In net timestamping case, if such an skb happens to be the last > one consumed in a recvmsg() call, the application receives no RX > timestamp for that call. > > Fix this by copying both tstamp and hwtstamp to the new skb right > after the initialization. > > Fixes: 98aaa913b4ed ("tcp: Extend SOF_TIMESTAMPING_RX_SOFTWARE to TCP recvmsg") > Signed-off-by: Jason Xing Reviewed-by: Xuanqiang Luo Thanks, Xuanqiang