K 10
svn:author
V 7
glebius
K 8
svn:date
V 27
2019-10-29T17:28:25.588277Z
K 7
svn:log
V 589
Merge td_epochnest with td_no_sleeping.

Epoch itself doesn't rely on the counter and it is provided
merely for sleeping subsystems to check it.

- In functions that sleep use THREAD_CAN_SLEEP() to assert
  correctness.  With EPOCH_TRACE compiled print epoch info.
- _sleep() was a wrong place to put the assertion for epoch,
  right place is sleepq_add(), as there ways to call the
  latter bypassing _sleep().
- Do not increase td_no_sleeping in non-preemptible epochs.
  The critical section would trigger all possible safeguards,
  no sleeping counter is extraneous.

Reviewed by:	kib

END