This procedure is called by “issig” (3999) if the tracing flag (“STRC”, 0395) is set.
If your parent is process 1 (i.e. “/etc/init”), then call “exit” (line 4032);
Otherwise look through “proc” for your parent ... wake him up ... declare yourself “stopped” and ... call “swtch” (Note do NOT call “sleep”. Why?);
If the tracing flag has been reset, or the result of the procedure “procxmt” is true, return to “issig”;
Otherwise start again.