From: Jason Xing kernelxing@tencent.com

When I was trying to modify the tx timestamping feature, I found that running "./txtimestamp -4 -C -L 127.0.0.1" didn't reflect the error: I succeeded to generate timestamp stored in the skb but later failed to report it to the userspace (which means failed to put css into cmsg). It can happen when someone writes buggy codes in __sock_recv_timestamp(), for example.

After adding the check so that running ./txtimestamp will reflect the result correctly like this if there is a bug in the reporting phase: protocol: TCP payload: 10 server port: 9000

family: INET test SND USR: 1725458477 s 667997 us (seq=0, len=0) Failed to report timestamps USR: 1725458477 s 718128 us (seq=0, len=0) Failed to report timestamps USR: 1725458477 s 768273 us (seq=0, len=0) Failed to report timestamps USR: 1725458477 s 818416 us (seq=0, len=0) Failed to report timestamps ...

In the future, it will help us detect whether the new coming patch has bugs or not.

Signed-off-by: Jason Xing kernelxing@tencent.com --- v2 Link: https://lore.kernel.org/all/20240904144446.41274-1-kerneljasonxing@gmail.com... 1. mainly change from "parse" to "report", update the commit message. --- tools/testing/selftests/net/txtimestamp.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/net/txtimestamp.c b/tools/testing/selftests/net/txtimestamp.c index ec60a16c9307..d626f22f9550 100644 --- a/tools/testing/selftests/net/txtimestamp.c +++ b/tools/testing/selftests/net/txtimestamp.c @@ -356,8 +356,12 @@ static void __recv_errmsg_cmsg(struct msghdr *msg, int payload_len) } }

- if (batch > 1) + if (batch > 1) { fprintf(stderr, "batched %d timestamps\n", batch); + } else if (!batch) { + fprintf(stderr, "Failed to report timestamps\n"); + test_failed = true; + } }

static int recv_errmsg(int fd)