phase A (forced interleave): xpt_done called 2 time(s) for one ccb; srboutstandingcount = -1 (started at 1)
phase B (natural race): 2,000,000 iterations, 1658716 double-completions observed

[+] DF-3710 CONFIRMED: both contexts can pass their srb_state guard before either acts -> one ccb completed twice (double xpt_done + srboutstandingcount underflow) in the unsynchronized kernel state machine.
RUN_EXIT=0