In D57511#1318443, @glebius wrote:

That's why I propose the remove this abstraction as it creates more trouble and obfuscation then benefit, IMHO. What's the point of abstraction if certain protocol calls are immediately short-circuited to a different function and the main sending (or receiving) loop is not entered at all?

Ok, let's hear from Pawel.

In D57511#1318085, @glebius wrote:

I really can't understand how this worked before FreeBSD 15. If one side sends less than 128 bytes, but other side says recv(s, buf, 128, MSG_WAITALL), then the other side shall hang always. I don't remember that my changes to unix(4) in FreeBSD 15 had fixed ignored MSG_WAITALL. Was that some other data sent after that woke up the receiver?