| Message ID | 20240911091333.1870071-1-vadfed@meta.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | Add option to provide OPT_ID value via cmsg | expand |
On Wed, 11 Sep 2024 02:13:30 -0700 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. Does not apply to net-next any more, sorry :(
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: v4 -> v5: - replace BUILD_BUG_ON_MSG with simple BUILD_BUG_ON - adjust comment about added flag and check - remove redefinition of flag from selftests - adjust tcp_tx_timestamp() to use sock cookie v3 -> v4: - remove static_assert from UAPI header - add BUILD_BUG_ON_MSG with some explanation - use SOF_TIMESTAMPING_OPT_ID flag in ipv4/ipv6 UDP case - move ts_opt_id initialization under flag check to avoid extra assignment in the hot path 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/CALCETrU0jB+kg0mhV6A8mrHfTE1D1pr1SD_B9Eaa9aDPfgHdtA@mail.gmail.com/ Vadim Fedorenko (3): net_tstamp: add SCM_TS_OPT_ID to provide OPT_ID in control message net_tstamp: add SCM_TS_OPT_ID for RAW sockets selftests: txtimestamp: add SCM_TS_OPT_ID test Documentation/networking/timestamping.rst | 14 +++++++ 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 | 34 ++++++++++++----- include/uapi/asm-generic/socket.h | 2 + net/can/raw.c | 2 +- net/core/sock.c | 13 +++++++ net/ipv4/ip_output.c | 21 ++++++++--- net/ipv4/raw.c | 2 +- net/ipv4/tcp.c | 7 ++-- net/ipv6/ip6_output.c | 22 +++++++---- 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 | 44 +++++++++++++++++----- tools/testing/selftests/net/txtimestamp.sh | 12 +++--- 20 files changed, 149 insertions(+), 48 deletions(-)