Subject: Re: [PATCH net-next v3 0/4] Add option to provide OPT_ID value via cmsg

From: Vadim Fedorenko <[email-masked]>
Date: Wed, 4 Sep 2024 12:36:45 +0100

On 04/09/2024 12:31, Vadim Fedorenko wrote:
> SOF_TIMESTAMPING_OPT_ID socket option flag gives a way to correlate TX
> timestamps and packets sent via socket. Unfortunately, there is no way
> to reliably predict socket timestamp ID value in case of error returned
> by sendmsg. For UDP sockets it's impossible because of lockless
> nature of UDP transmit, several threads may send packets in parallel. In
> case of RAW sockets MSG_MORE option makes things complicated. More
> details are in the conversation [1].
> This patch adds new control message type to give user-space
> software an opportunity to control the mapping between packets and
> values by providing ID with each sendmsg.
> 
> The first patch in the series adds all needed definitions and implements
> the function for UDP sockets. The explicit check of socket's type is not
> added because subsequent patches in the series will add support for other
> types of sockets. The documentation is also included into the first
> patch.
> 
> Patch 2/4 adds support for TCP sockets. This part is simple and straight
> forward.
> 
> Patch 3/4 adds support for RAW sockets. It's a bit tricky because
> sock_tx_timestamp functions has to be refactored to receive full socket
> cookie information to fill in ID. The commit b534dc46c8ae ("net_tstamp:
> add SOF_TIMESTAMPING_OPT_ID_TCP") did the conversion of sk_tsflags to
> u32 but sock_tx_timestamp functions were not converted and still receive
> 16b flags. It wasn't a problem because SOF_TIMESTAMPING_OPT_ID_TCP was
> not checked in these functions, that's why no backporting is needed.
> 
> Patch 4/4 adds selftests for new feature.
> 
> Changelog:
> v2 -> v3:
> - remove SOF_TIMESTAMPING_OPT_ID_CMSG UAPI value and use kernel-internal
>    SOCKCM_FLAG_TS_OPT_ID which uses the highest bit of tsflags.
> - add support for TCP and RAW sockets
> v1 -> v2:
> - add more selftests
> - add documentation for the feature
> - refactor UDP send function
> RFC -> v1:
> - add selftests
> - add SOF_TIMESTAMPING_OPT_ID_CMSG to signal of custom ID provided by
> 	user-space instead of reserving value of 0 for this.
> 
> [1] https://lore.kernel.org/netdev/[email-masked]/
> 
> Vadim Fedorenko (4):
>    net_tstamp: add SCM_TS_OPT_ID to provide OPT_ID in control message
>    net_tstamp: add SCM_TS_OPT_ID for TCP sockets
>    net_tstamp: add SCM_TS_OPT_ID for RAW sockets
>    selftests: txtimestamp: add SCM_TS_OPT_ID test
> 
>   Documentation/networking/timestamping.rst  | 13 ++++++
>   arch/alpha/include/uapi/asm/socket.h       |  2 +
>   arch/mips/include/uapi/asm/socket.h        |  2 +
>   arch/parisc/include/uapi/asm/socket.h      |  2 +
>   arch/sparc/include/uapi/asm/socket.h       |  2 +
>   include/net/inet_sock.h                    |  4 +-
>   include/net/sock.h                         | 29 +++++++++----
>   include/uapi/asm-generic/socket.h          |  2 +
>   include/uapi/linux/net_tstamp.h            |  7 ++++
>   net/can/raw.c                              |  2 +-
>   net/core/sock.c                            |  9 ++++
>   net/ipv4/ip_output.c                       | 20 ++++++---
>   net/ipv4/raw.c                             |  2 +-
>   net/ipv4/tcp.c                             | 15 ++++---
>   net/ipv6/ip6_output.c                      | 20 ++++++---
>   net/ipv6/raw.c                             |  2 +-
>   net/packet/af_packet.c                     |  6 +--
>   net/socket.c                               |  2 +-
>   tools/include/uapi/asm-generic/socket.h    |  2 +
>   tools/testing/selftests/net/txtimestamp.c  | 48 +++++++++++++++++-----
>   tools/testing/selftests/net/txtimestamp.sh | 12 +++---
>   21 files changed, 154 insertions(+), 49 deletions(-)
> 
Oh, sorry for the mess, patches:

[PATCH v3 2/3] selftests: txtimestamp: add SCM_TS_OPT_ID test
[PATCH v3 3/3] net_tstamp: add SCM_TS_OPT_ID for TCP sockets

should be ignored.

If it too messy I can resend the series.

Sorry again,
Vadim