hw.df5563.busy: 0 -> 1
--- ps t0 (watch TIME) ---
   PID STAT        TIME COMMAND
  2007 R1       0:03.01 ./park nowait
--- ps t1 (+3s) ---
   PID STAT        TIME COMMAND
  2007 R1       0:06.01 ./park nowait
--- kill -9 ---
   PID STAT        TIME COMMAND
  2007 R1       0:09.01 ./park nowait
SIGKILL_IGNORED=YES
--- unbusy: loop must exit within one callback ---
hw.df5563.busy: 1 -> 0
   PID STAT   COMMAND
GONE_AFTER_UNBUSY=YES
[park 2007] ioctl 0xc0046403 on /dev/df5563...