From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-183.mta1.migadu.com (out-183.mta1.migadu.com [95.215.58.183]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6AED876416 for ; Thu, 14 Mar 2024 21:49:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.183 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1710452948; cv=none; b=cjXSGiEQhZJsOwnO6cddTDk9/mFZc+RDu4hF9QIthWzFjpCoVHSMEGWHK/Anl0X5yFwxZ1xoQHlBTeawkwz56MLcY/+21yAJwtc17Vy2stFIa8pDEmfj2lZeUxgqh77wcl2VyieeWTj3PSwhzNh8ZPdgJ9f9F4G+FL5uQcrEgZM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1710452948; c=relaxed/simple; bh=FeBtDwOwx7bWu5qqepAggjxF5zHLaj9k63HtMHOYRCs=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=N3qcXEP3Ma4u2yOf8pufUyityO21zh6f4HYr3No4u3gHjP14RdNyxoSr6HGqmCStql4asOky/V6iYnyFbTA9IC0nbOGMOVprdAK0q2sG5nB1fXWygJR6My/elLIG/JTkQ/Pcex3PUdKmLuwZ1ispRTtquzD6ywH4INMlFWQBKAk= 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=BzvnEIZg; arc=none smtp.client-ip=95.215.58.183 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="BzvnEIZg" Message-ID: <8d245f5a-0c75-4634-9513-3d420eb2c88f@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1710452944; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=QiN7/QrqzPkJR7UExDk5VS/K0g1YOEpPfbnDYYLfHKA=; b=BzvnEIZguvRsFkfCMDSsqBRA0YDLTewPY+PyvE54orrRY00M8cT+U55PL+AIx5KowPs0Zi PyblWOHzvDbfeLcaGRyHiqxCT/8AF4WvCkDUufefzIHP466E85+N7i3IVlPQHygwlaW1MD uMZfBzmTV/FSHjTOodeLuBMkonw/c94= Date: Thu, 14 Mar 2024 14:48:54 -0700 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH net-next v4] net: Re-use and set mono_delivery_time bit for userspace tstamp packets Content-Language: en-US To: "Abhishek Chauhan (ABC)" Cc: Willem de Bruijn , kernel@quicinc.com, "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Andrew Halaney , Martin KaFai Lau , bpf , Daniel Borkmann , Alexei Starovoitov , Andrii Nakryiko References: <20240301201348.2815102-1-quic_abchauha@quicinc.com> <2a4cb416-5d95-459d-8c1c-3fb225240363@linux.dev> <65f16946cd33e_344ff1294fc@willemb.c.googlers.com.notmuch> <28282905-065a-4233-a0a2-53aa9b85f381@linux.dev> <65f2004e65802_3d1e792943e@willemb.c.googlers.com.notmuch> <0dff8f05-e18d-47c8-9f19-351c44ea8624@linux.dev> <65f21d65820fc_3d934129463@willemb.c.googlers.com.notmuch> <65f2c81fc7988_3ee61729465@willemb.c.googlers.com.notmuch> <5692ddb3-9558-4440-a7bf-47fcc47401ed@linux.dev> <65f35e00a83c0_2132294f5@willemb.c.googlers.com.notmuch> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Martin KaFai Lau In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Migadu-Flow: FLOW_OUT On 3/14/24 1:53 PM, Abhishek Chauhan (ABC) wrote: >>> The bpf_convert_tstamp_{read,write} and the helper bpf_skb_set_tstamp need to be >>> changed to handle the new "user_delivery_time" bit anyway, e.g. >>> bpf_skb_set_tstamp(BPF_SKB_TSTAMP_DELIVERY_MONO) needs to clear the >>> "user_delivery_time" bit. >>> >>> I think the "struct inet_frag_queue" also needs a new "user_delivery_time" >>> field. "mono_delivery_time" is already in there. [ ... ] I would think the first step is to revert this patch. I don't think much of the current patch can be reused. > 1. I will raise one patch to introduce rename mono_delivery_time to > tstamp_type Right, I expect something like this: struct sk_buff { /* ... */ - __u8 mono_delivery_time:1; + __u8 tstamp_type:1; /* ... */ }; > 2. I will introduce setting of userspace timestamp type as the second bit > whem transmit_time is set. I expect the second patch should be introducing the enum first enum skb_tstamp_type { SKB_TSTAMP_TYPE_RX_REAL = 0, /* A RX (receive) time in real */ SKB_TSTAMP_TYPE_TX_MONO = 1, /* A TX (delivery) time in mono */ }; and start doing "skb->tstamp_type = SKB_TSTAMP_TYPE_TX_MONO;" instead of "skb->tstamp_type = 1;" and the same for "skb->tstamp_type = SKB_TSTAMP_TYPE_RX_REAL;" instead of "skb->tstamp_type = 0;" This one I am not sure but probably need to change the skb_set_delivery_time() function signature also: static inline void skb_set_delivery_time(struct sk_buff *skb, ktime_t kt, - bool mono) + enum skb_tstamp_type tstamp_type) The third patch is to change tstamp_type from 1 bit to 2 bits and add SKB_TSTAMP_TYPE_TX_USER. struct sk_buff { /* ... */ - __u8 tstamp_type:1; + __u8 tstamp_type:2; /* ... */ }; enum skb_tstamp_type { SKB_TSTAMP_TYPE_RX_REAL = 0, /* A RX (receive) time in real */ SKB_TSTAMP_TYPE_TX_MONO = 1, /* A TX (delivery) time in mono */ + SKB_TSTAMP_TYPE_TX_USER = 2, /* A TX (delivery) time and its clock * is in skb->sk->sk_clockid. */ }; This will shift a bit out of the byte where tstamp_type lives. It should be the "inner_protocol_type" bit by my hand count. Please check if it is directly used in bpf instruction (filter.c). As far as I look, it is not, so should be fine. Some details about bpf instruction accessible skb bit field here: https://lore.kernel.org/all/20230321014115.997841-1-kuba@kernel.org/ > 3. This will be a first step to make the design scalable. > 4. Tomorrow if we have more timestamp to support, upstream community has to do is > update the enum and increase the bitfield from 2=>3 and so on. > > I need help from Martin to test the patch which renames the mono_delivery_time > to tstamp_type (Which i feel should be straight forward as the value of the bit is 1) The bpf change is not a no-op rename of mono_delivery_time. It needs to take care of the new bit added to the tstamp_type. Please see the previous email (and I also left it in the beginning of this email). Thus, you need to compile the selftests/bpf/ and run it to verify the changes when handling the new bit. The Documentation/bpf/bpf_devel_QA.rst has the howto details. You probably only need the newer llvm (newer gcc should work also as bpf CI has been using it) and the newer pahole. I can definitely help if there is issue in running the test_progs in selftests/bpf or you have question on making the changes in filter.c. To run the test: "./test_progs -t tc_redirect/tc_redirect_dtime"