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kernel/sched: Fix reschedule points in SMP

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There were two related bugs when in SMP mode:

1. Underneath z_reschedule(), the code was inexplicably checking the
   swap_ok flag on the current CPU to see if it was OK to preempt the
   current thread, but reschedule is the DEFINITION of a schedule
   point and we always want to swap, even if the current thread is
   non-preemptible.

2. With similar symptoms: in k_yield() a previous fix correct the
   queue handling for SMP, but it missed the case where a thread of
   the SAME priority as _current was on the queue and would fail to
   swap.  Yielding must always add the current thread to the back of
   the current priority.

Signed-off-by: Andy Ross <andrew.j.ross@intel.com>
This commit is contained in:
Andy Ross 2019-08-16 13:14:51 -07:00 • committed by Anas Nashif
commit b0158cc81f
1 changed files with 2 additions and 5 deletions
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7
kernel/sched.c
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@ -523,9 +523,6 @@ void z_thread_priority_set(struct k_thread *thread, int prio)
static inline int resched(u32_t key)
{
#ifdef CONFIG_SMP
if (!_current_cpu->swap_ok) {
return 0;
}
_current_cpu->swap_ok = 0;
#endif
@ -919,9 +916,9 @@ void z_impl_k_yield(void)
z_is_thread_queued(_current)) {
_priq_run_remove(&_kernel.ready_q.runq,
_current);
_priq_run_add(&_kernel.ready_q.runq,
_current);
}
_priq_run_add(&_kernel.ready_q.runq, _current);
z_mark_thread_as_queued(_current);
update_cache(1);
}
}