From: Jason Xing kernelxing@tencent.com
When one socket is set SOF_TIMESTAMPING_RX_SOFTWARE which means the whole system turns on the netstamp_needed_key button, other sockets that only have SOF_TIMESTAMPING_SOFTWARE will be affected and then print the rx timestamp information even without setting SOF_TIMESTAMPING_RX_SOFTWARE generation flag.
How to solve it without breaking users? We introduce a new flag named SOF_TIMESTAMPING_OPT_RX_FILTER. Using it together with SOF_TIMESTAMPING_SOFTWARE can stop reporting the rx software timestamp.
Similarly, we also filter out the hardware case where one process enables the rx hardware generation flag, then another process only passing SOF_TIMESTAMPING_RAW_HARDWARE gets the timestamp. So we can set both SOF_TIMESTAMPING_RAW_HARDWARE and SOF_TIMESTAMPING_OPT_RX_FILTER to stop reporting rx hardware timestamp after this patch applied.
v4 Link: https://lore.kernel.org/all/20240830153751.86895-1-kerneljasonxing@gmail.com... 1. revise the doc and commit message (Willem) 2. add patch [2/4] to make the doc right (Willem) 3. add patch [3/4] to cover the hardware use (Willem) 4. add testcase for hardware use. Note: the reason why I split into 4 patches is try to make each commit clean, atomic, easy to review.
v3 Link: https://lore.kernel.org/all/20240828160145.68805-1-kerneljasonxing@gmail.com... 1. introduce a new flag to avoid application breakage, suggested by Willem. 2. add it into the selftests.
v2 Link: https://lore.kernel.org/all/20240825152440.93054-1-kerneljasonxing@gmail.com... Discussed with Willem 1. update the documentation accordingly 2. add more comments in each patch 3. remove the previous test statements in __sock_recv_timestamp()
Jason Xing (4): net-timestamp: filter out report when setting SOF_TIMESTAMPING_SOFTWARE net-timestamp: correct the use of SOF_TIMESTAMPING_RAW_HARDWARE net-timestamp: extend SOF_TIMESTAMPING_OPT_RX_FILTER for hardware use rxtimestamp.c: add the test for SOF_TIMESTAMPING_OPT_RX_FILTER
Documentation/networking/timestamping.rst | 18 +++++++++++++++++- include/uapi/linux/net_tstamp.h | 3 ++- net/core/sock.c | 5 +++++ net/ethtool/common.c | 1 + net/ipv4/tcp.c | 7 +++++-- net/socket.c | 7 +++++-- tools/testing/selftests/net/rxtimestamp.c | 11 +++++++++++ 7 files changed, 46 insertions(+), 6 deletions(-)