kernel/sched: Don't preempt cooperative threads
The scheduler rewrite added a regression in uniprocessor mode where
cooperative threads would be unexpectedly preempted, because nothing
was checking the preemption status of _current at the point where the
next-thread cache pointer was being updated.
Note that update_cache() needs a little more context: spots like
k_yield() that leave _current runable need to be able to tell it that
"yes, preemption is OK here even though the thread is cooperative'.
So it has a "preempt_ok" argument now.
Interestingly this didn't get caught because we don't test that. We
have lots and lots of tests of the converse cases (i.e. making sure
that threads get preempted when we expect them to), but nothing that
explicitly tries to jump in front of a cooperative thread.
Signed-off-by: Andy Ross <andrew.j.ross@intel.com>
1 file changed
