Support write to a listen TCP socket, for immediate
transmission on passive connection establishments.
On a normal connection transmission is triggered by the receipt of
the 3rd-ack. On a fastopen (with accepted cookie) connection the data
is sent in the synack packet.
The data preload is done using a sendmsg with a newly-defined flag
(MSG_PRELOAD); the amount of data limited to a single linear sk_buff.
Note that this definition is the last-but-two bit available if "int"
is 32 bits.
Testing:
A) packetdrill scripts for
- normal non-TFO
- normal TFO
- synack lost
- 3rd-ack acks only the SYN
- 3rd-ack acks partial data
(NB: packetdrill can only check the data size, not actual content)
B) Application use, running the application testsuite
and manual check of specific cases via packet capture
C) Daily-driver laptop use (not expected to trigger the feature;
only regression-test)
Jeremy Harris (6):
tcp: support writing to a socket in listening state
tcp: copy write-data from listen socket to accept child socket
tcp: fastopen: add write-data to fastopen synack packet
tcp: transmit any pending data on receipt of 3rd-ack
tcp: fastopen: retransmit data when only the SYN of a synack-with-data
is acked
tcp: fastopen: extend retransmit-queue trimming to handle linear
sk_buff
include/linux/socket.h | 1 +
net/ipv4/tcp.c | 17 ++++--
net/ipv4/tcp_fastopen.c | 3 +-
net/ipv4/tcp_input.c | 15 ++++-
net/ipv4/tcp_ipv4.c | 4 +-
net/ipv4/tcp_minisocks.c | 58 +++++++++++++++++--
net/ipv4/tcp_output.c | 50 ++++++++++++++--
.../perf/trace/beauty/include/linux/socket.h | 1 +
tools/perf/trace/beauty/msg_flags.c | 3 +
9 files changed, 135 insertions(+), 17 deletions(-)
base-commit: 2da35e4b4df99d3dd29bacf0c054e6988013d4ec
--
2.49.0
