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kernel: Scheduler refactoring: use _reschedule_*() always

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There was a somewhat promiscuous pattern in the kernel where IPC
mechanisms would do something that might effect the current thread
choice, then check _must_switch_threads() (or occasionally
__must_switch_threads -- don't ask, the distinction is being replaced
by real English words), sometimes _is_in_isr() (but not always, even
in contexts where that looks like it would be a mistake), and then
call _Swap() if everything is OK, otherwise releasing the irq_lock().
Sometimes this was done directly, sometimes via the inverted test,
sometimes (poll, heh) by doing the test when the thread state was
modified and then needlessly passing the result up the call stack to
the point of the _Swap().

And some places were just calling _reschedule_threads(), which did all
this already.

Unify all this madness.  The old _reschedule_threads() function has
split into two variants: _reschedule_yield() and
_reschedule_noyield().  The latter is the "normal" one that respects
the cooperative priority of the current thread (i.e. it won't switch
out even if there is a higher priority thread ready -- the current
thread has to pend itself first), the former is used in the handful of
places where code was doing a swap unconditionally, just to preserve
precise behavior across the refactor.  I'm not at all convinced it
should exist...

Signed-off-by: Andy Ross <andrew.j.ross@intel.com>
This commit is contained in:
Andy Ross 2018-03-26 10:54:40 -07:00 • committed by Anas Nashif
commit 8606fabf74
19 changed files with 78 additions and 196 deletions
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45
kernel/queue.c
View file

@ -68,13 +68,10 @@ static void prepare_thread_to_run(struct k_thread *thread, void *data)
}
#endif /* CONFIG_POLL */
/* returns 1 if a reschedule must take place, 0 otherwise */
static inline int handle_poll_events(struct k_queue *queue, u32_t state)
static inline void handle_poll_events(struct k_queue *queue, u32_t state)
{
#ifdef CONFIG_POLL
return _handle_obj_poll_events(&queue->poll_events, state);
#else
return 0;
_handle_obj_poll_events(&queue->poll_events, state);
#endif
}
@ -88,19 +85,12 @@ void k_queue_cancel_wait(struct k_queue *queue)
if (first_pending_thread) {
prepare_thread_to_run(first_pending_thread, NULL);
if (!_is_in_isr() && _must_switch_threads()) {
(void)_Swap(key);
return;
}
}
#else
if (handle_poll_events(queue, K_POLL_STATE_NOT_READY)) {
(void)_Swap(key);
return;
}
handle_poll_events(queue, K_POLL_STATE_NOT_READY);
#endif /* !CONFIG_POLL */
irq_unlock(key);
_reschedule_noyield(key);
}
void k_queue_insert(struct k_queue *queue, void *prev, void *data)
@ -113,11 +103,7 @@ void k_queue_insert(struct k_queue *queue, void *prev, void *data)
if (first_pending_thread) {
prepare_thread_to_run(first_pending_thread, data);
if (!_is_in_isr() && _must_switch_threads()) {
(void)_Swap(key);
return;
}
irq_unlock(key);
_reschedule_noyield(key);
return;
}
#endif /* !CONFIG_POLL */
@ -125,13 +111,10 @@ void k_queue_insert(struct k_queue *queue, void *prev, void *data)
sys_slist_insert(&queue->data_q, prev, data);
#if defined(CONFIG_POLL)
if (handle_poll_events(queue, K_POLL_STATE_DATA_AVAILABLE)) {
(void)_Swap(key);
return;
}
handle_poll_events(queue, K_POLL_STATE_DATA_AVAILABLE);
#endif /* CONFIG_POLL */
irq_unlock(key);
_reschedule_noyield(key);
}
void k_queue_append(struct k_queue *queue, void *data)
@ -148,7 +131,6 @@ void k_queue_append_list(struct k_queue *queue, void *head, void *tail)
{
__ASSERT(head && tail, "invalid head or tail");
int need_sched = 0;
unsigned int key = irq_lock();
#if !defined(CONFIG_POLL)
struct k_thread *thread;
@ -156,7 +138,6 @@ void k_queue_append_list(struct k_queue *queue, void *head, void *tail)
while (head && ((thread = _unpend_first_thread(&queue->wait_q)))) {
prepare_thread_to_run(thread, head);
head = *(void **)head;
need_sched = 1;
}
if (head) {
@ -165,18 +146,10 @@ void k_queue_append_list(struct k_queue *queue, void *head, void *tail)
#else
sys_slist_append_list(&queue->data_q, head, tail);
if (handle_poll_events(queue, K_POLL_STATE_DATA_AVAILABLE)) {
(void)_Swap(key);
return;
}
handle_poll_events(queue, K_POLL_STATE_DATA_AVAILABLE);
#endif /* !CONFIG_POLL */
if (need_sched) {
_reschedule_threads(key);
return;
} else {
irq_unlock(key);
}
_reschedule_noyield(key);
}
void k_queue_merge_slist(struct k_queue *queue, sys_slist_t *list)