In particular:
- Don't evaluate event conditions with a sleepqueue lock held, since such
code may attempt to acquire arbitrary locks.
- Fix the return value for wait_event_interruptible() in the case that the
wait is interrupted by a signal.
- Implement wait_on_bit_timeout() and wait_on_atomic_t().
- Implement some functions used to test for pending signals.
- Implement a number of wait_event_*() variants and unify the existing
implementations.
- Unify the mechanism used by wait_event_*() and schedule() to put the
calling thread to sleep.
This is required to support updated DRM drivers. Thanks to hselasky for
finding and fixing a number of bugs in the original revision.
Reviewed by: hselasky
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D10986
465659643b