In the current code, the locking is completely broken and may lead
easilly to deadlocks. Fix it by using the proc_mtx, linked to the
suspending thread, as lock for the operation. Keep using the
thread_lock for setting and reading the flag even if it is not entirely
necessary (atomic ops may do it as well, but this way the code is more
readable).
- Fix a deadlock within kthread_suspend().
The suspender should not sleep on a different channel wrt the suspended
thread, or, otherwise, the awaker should wakeup both. Uniform the
interface to what the kproc_* counterparts do (sleeping on the same
channel).
- Change the kthread_suspend_check() prototype.
kthread_suspend_check() always assumes curthread and must only refer to
it, so skip the thread pointer as it may be easilly mistaken.
If curthread is not a kthread, the system will panic.
In collabouration with: jhb
Tested by: Giovanni Trematerra
<giovanni dot trematerra at gmail dot com>
MFC: 2 weeks
the kthread_create(9) man page to the kproc(9) page as it had migrated and
people looking for it may need a hand to find its new name.
MFC after: 1 week
Remove invalid return values.
Remove reference to non-existent manual pages.
Remove reference to rfork (it does not discuss RFSTOPPED).
Add sys/unistd.h to the list of includes (required for RFSTOPPED).
PR: 126227
Submitted by: Mateusz Guzik <mjguzik@gmail.com> (based on, original version)
Reviewed by: jhb, Christoph Mallon <christoph.mallon@gmx.de>
- Kthread functions return an error status, they don't set errno to an
error status.
- Remove the BUGS section as all the bugs listed have been fixed now.
