Any change in when so_rcv_mtx is destroyed for UDP?

Hi,

PR#292884 shows a crash where the server side
udp krpc crashes when trying to SOCK_RECVBUF_LOCK()
after soreceive() returns EWOULDBLOCK.

The code looks like:
     error = soreceive(..);
     if (error == EWOULDBLOCK) {
          SOCK_RECVBUF_LOCK();

The only time the server side of the krpc does a soclose()
on a UDP socket is after the refcnt on the xprt structure that
the socket is in goes to 0. Since this code hasn't changed in
a long time, I doubt there is a refcnt problem.

So, is there any change in when so_rcv_mtx gets destroyed
for UDP sockets between FreeBSD-14 and FreeBSD-15?
(Or is there any condition where the so_rcv_mtx gets destroyed
for a UDP socket without a soclose(so) being done?)

If you want to look at the code where the crash occurs,
sys/rpc/svc_dg.c around line# 190.

Thanks for any hints on how this could occur, rick