This reminds me of a bug I had to fix while working on the AIX version of a SCSI-failover driver (ATF) for Clariion disk arrays.  It turned out that <i>sometimes</i>, telnet&#x27;ing in to a system with ATF active would hang the system.  (FWIW, ssh would have had the same problem.  That&#x27;s just not what actually happened, and ssh on AIX wasn&#x27;t much of a thing back in those days.)  It turned out that the telnet daemon and an ATF daemon together were triggering a classic lock-inversion kind of deadlock in the AIX kernel&#x27;s generic ioctl code.  The details and the fix aren&#x27;t all that relevant, but it was an important lesson in how these absolutely crazy-seeming kinds of interactions can and do occur in real systems.  If your code even runs &quot;alongside&quot; some other code, they can interact in strange and unpleasant ways.