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sched.c
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/*
* Copyright (c) 2018 Intel Corporation
*
* SPDX-License-Identifier: Apache-2.0
*/
#include <zephyr/kernel.h>
#include <ksched.h>
#include <zephyr/spinlock.h>
#include <wait_q.h>
#include <kthread.h>
#include <priority_q.h>
#include <kswap.h>
#include <ipi.h>
#include <kernel_arch_func.h>
#include <zephyr/internal/syscall_handler.h>
#include <zephyr/drivers/timer/system_timer.h>
#include <stdbool.h>
#include <kernel_internal.h>
#include <zephyr/logging/log.h>
#include <zephyr/sys/atomic.h>
#include <zephyr/sys/math_extras.h>
#include <zephyr/timing/timing.h>
#include <zephyr/sys/util.h>
LOG_MODULE_DECLARE(os, CONFIG_KERNEL_LOG_LEVEL);
#if defined(CONFIG_SWAP_NONATOMIC) && defined(CONFIG_TIMESLICING)
extern struct k_thread *pending_current;
#endif
struct k_spinlock _sched_spinlock;
/* Storage to "complete" the context switch from an invalid/incomplete thread
* context (ex: exiting an ISR that aborted _current)
*/
__incoherent struct k_thread _thread_dummy;
static ALWAYS_INLINE void update_cache(int preempt_ok);
static void halt_thread(struct k_thread *thread, uint8_t new_state);
static void add_to_waitq_locked(struct k_thread *thread, _wait_q_t *wait_q);
BUILD_ASSERT(CONFIG_NUM_COOP_PRIORITIES >= CONFIG_NUM_METAIRQ_PRIORITIES,
"You need to provide at least as many CONFIG_NUM_COOP_PRIORITIES as "
"CONFIG_NUM_METAIRQ_PRIORITIES as Meta IRQs are just a special class of cooperative "
"threads.");
/*
* Return value same as e.g. memcmp
* > 0 -> thread 1 priority > thread 2 priority
* = 0 -> thread 1 priority == thread 2 priority
* < 0 -> thread 1 priority < thread 2 priority
* Do not rely on the actual value returned aside from the above.
* (Again, like memcmp.)
*/
int32_t z_sched_prio_cmp(struct k_thread *thread_1,
struct k_thread *thread_2)
{
/* `prio` is <32b, so the below cannot overflow. */
int32_t b1 = thread_1->base.prio;
int32_t b2 = thread_2->base.prio;
if (b1 != b2) {
return b2 - b1;
}
#ifdef CONFIG_SCHED_DEADLINE
/* If we assume all deadlines live within the same "half" of
* the 32 bit modulus space (this is a documented API rule),
* then the latest deadline in the queue minus the earliest is
* guaranteed to be (2's complement) non-negative. We can
* leverage that to compare the values without having to check
* the current time.
*/
uint32_t d1 = thread_1->base.prio_deadline;
uint32_t d2 = thread_2->base.prio_deadline;
if (d1 != d2) {
/* Sooner deadline means higher effective priority.
* Doing the calculation with unsigned types and casting
* to signed isn't perfect, but at least reduces this
* from UB on overflow to impdef.
*/
return (int32_t) (d2 - d1);
}
#endif /* CONFIG_SCHED_DEADLINE */
return 0;
}
static ALWAYS_INLINE void *thread_runq(struct k_thread *thread)
{
#ifdef CONFIG_SCHED_CPU_MASK_PIN_ONLY
int cpu, m = thread->base.cpu_mask;
/* Edge case: it's legal per the API to "make runnable" a
* thread with all CPUs masked off (i.e. one that isn't
* actually runnable!). Sort of a wart in the API and maybe
* we should address this in docs/assertions instead to avoid
* the extra test.
*/
cpu = m == 0 ? 0 : u32_count_trailing_zeros(m);
return &_kernel.cpus[cpu].ready_q.runq;
#else
ARG_UNUSED(thread);
return &_kernel.ready_q.runq;
#endif /* CONFIG_SCHED_CPU_MASK_PIN_ONLY */
}
static ALWAYS_INLINE void *curr_cpu_runq(void)
{
#ifdef CONFIG_SCHED_CPU_MASK_PIN_ONLY
return &arch_curr_cpu()->ready_q.runq;
#else
return &_kernel.ready_q.runq;
#endif /* CONFIG_SCHED_CPU_MASK_PIN_ONLY */
}
static ALWAYS_INLINE void runq_add(struct k_thread *thread)
{
__ASSERT_NO_MSG(!z_is_idle_thread_object(thread));
_priq_run_add(thread_runq(thread), thread);
}
static ALWAYS_INLINE void runq_remove(struct k_thread *thread)
{
__ASSERT_NO_MSG(!z_is_idle_thread_object(thread));
_priq_run_remove(thread_runq(thread), thread);
}
static ALWAYS_INLINE struct k_thread *runq_best(void)
{
return _priq_run_best(curr_cpu_runq());
}
/* _current is never in the run queue until context switch on
* SMP configurations, see z_requeue_current()
*/
static inline bool should_queue_thread(struct k_thread *thread)
{
return !IS_ENABLED(CONFIG_SMP) || (thread != _current);
}
static ALWAYS_INLINE void queue_thread(struct k_thread *thread)
{
thread->base.thread_state |= _THREAD_QUEUED;
if (should_queue_thread(thread)) {
runq_add(thread);
}
#ifdef CONFIG_SMP
if (thread == _current) {
/* add current to end of queue means "yield" */
_current_cpu->swap_ok = true;
}
#endif /* CONFIG_SMP */
}
static ALWAYS_INLINE void dequeue_thread(struct k_thread *thread)
{
thread->base.thread_state &= ~_THREAD_QUEUED;
if (should_queue_thread(thread)) {
runq_remove(thread);
}
}
/* Called out of z_swap() when CONFIG_SMP. The current thread can
* never live in the run queue until we are inexorably on the context
* switch path on SMP, otherwise there is a deadlock condition where a
* set of CPUs pick a cycle of threads to run and wait for them all to
* context switch forever.
*/
void z_requeue_current(struct k_thread *thread)
{
if (z_is_thread_queued(thread)) {
runq_add(thread);
}
signal_pending_ipi();
}
/* Return true if the thread is aborting, else false */
static inline bool is_aborting(struct k_thread *thread)
{
return (thread->base.thread_state & _THREAD_ABORTING) != 0U;
}
/* Return true if the thread is aborting or suspending, else false */
static inline bool is_halting(struct k_thread *thread)
{
return (thread->base.thread_state &
(_THREAD_ABORTING | _THREAD_SUSPENDING)) != 0U;
}
/* Clear the halting bits (_THREAD_ABORTING and _THREAD_SUSPENDING) */
static inline void clear_halting(struct k_thread *thread)
{
barrier_dmem_fence_full(); /* Other cpus spin on this locklessly! */
thread->base.thread_state &= ~(_THREAD_ABORTING | _THREAD_SUSPENDING);
}
static ALWAYS_INLINE struct k_thread *next_up(void)
{
#ifdef CONFIG_SMP
if (is_halting(_current)) {
halt_thread(_current, is_aborting(_current) ?
_THREAD_DEAD : _THREAD_SUSPENDED);
}
#endif /* CONFIG_SMP */
struct k_thread *thread = runq_best();
#if (CONFIG_NUM_METAIRQ_PRIORITIES > 0) && \
(CONFIG_NUM_COOP_PRIORITIES > CONFIG_NUM_METAIRQ_PRIORITIES)
/* MetaIRQs must always attempt to return back to a
* cooperative thread they preempted and not whatever happens
* to be highest priority now. The cooperative thread was
* promised it wouldn't be preempted (by non-metairq threads)!
*/
struct k_thread *mirqp = _current_cpu->metairq_preempted;
if (mirqp != NULL && (thread == NULL || !thread_is_metairq(thread))) {
if (!z_is_thread_prevented_from_running(mirqp)) {
thread = mirqp;
} else {
_current_cpu->metairq_preempted = NULL;
}
}
#endif
/* CONFIG_NUM_METAIRQ_PRIORITIES > 0 &&
* CONFIG_NUM_COOP_PRIORITIES > CONFIG_NUM_METAIRQ_PRIORITIES
*/
#ifndef CONFIG_SMP
/* In uniprocessor mode, we can leave the current thread in
* the queue (actually we have to, otherwise the assembly
* context switch code for all architectures would be
* responsible for putting it back in z_swap and ISR return!),
* which makes this choice simple.
*/
return (thread != NULL) ? thread : _current_cpu->idle_thread;
#else
/* Under SMP, the "cache" mechanism for selecting the next
* thread doesn't work, so we have more work to do to test
* _current against the best choice from the queue. Here, the
* thread selected above represents "the best thread that is
* not current".
*
* Subtle note on "queued": in SMP mode, _current does not
* live in the queue, so this isn't exactly the same thing as
* "ready", it means "is _current already added back to the
* queue such that we don't want to re-add it".
*/
bool queued = z_is_thread_queued(_current);
bool active = !z_is_thread_prevented_from_running(_current);
if (thread == NULL) {
thread = _current_cpu->idle_thread;
}
if (active) {
int32_t cmp = z_sched_prio_cmp(_current, thread);
/* Ties only switch if state says we yielded */
if ((cmp > 0) || ((cmp == 0) && !_current_cpu->swap_ok)) {
thread = _current;
}
if (!should_preempt(thread, _current_cpu->swap_ok)) {
thread = _current;
}
}
/* Put _current back into the queue */
if ((thread != _current) && active &&
!z_is_idle_thread_object(_current) && !queued) {
queue_thread(_current);
}
/* Take the new _current out of the queue */
if (z_is_thread_queued(thread)) {
dequeue_thread(thread);
}
_current_cpu->swap_ok = false;
return thread;
#endif /* CONFIG_SMP */
}
void move_thread_to_end_of_prio_q(struct k_thread *thread)
{
if (z_is_thread_queued(thread)) {
dequeue_thread(thread);
}
queue_thread(thread);
update_cache(thread == _current);
}
/* Track cooperative threads preempted by metairqs so we can return to
* them specifically. Called at the moment a new thread has been
* selected to run.
*/
static void update_metairq_preempt(struct k_thread *thread)
{
#if (CONFIG_NUM_METAIRQ_PRIORITIES > 0) && \
(CONFIG_NUM_COOP_PRIORITIES > CONFIG_NUM_METAIRQ_PRIORITIES)
if (thread_is_metairq(thread) && !thread_is_metairq(_current) &&
!thread_is_preemptible(_current)) {
/* Record new preemption */
_current_cpu->metairq_preempted = _current;
} else if (!thread_is_metairq(thread) && !z_is_idle_thread_object(thread)) {
/* Returning from existing preemption */
_current_cpu->metairq_preempted = NULL;
}
#else
ARG_UNUSED(thread);
#endif
/* CONFIG_NUM_METAIRQ_PRIORITIES > 0 &&
* CONFIG_NUM_COOP_PRIORITIES > CONFIG_NUM_METAIRQ_PRIORITIES
*/
}
static ALWAYS_INLINE void update_cache(int preempt_ok)
{
#ifndef CONFIG_SMP
struct k_thread *thread = next_up();
if (should_preempt(thread, preempt_ok)) {
#ifdef CONFIG_TIMESLICING
if (thread != _current) {
z_reset_time_slice(thread);
}
#endif /* CONFIG_TIMESLICING */
update_metairq_preempt(thread);
_kernel.ready_q.cache = thread;
} else {
_kernel.ready_q.cache = _current;
}
#else
/* The way this works is that the CPU record keeps its
* "cooperative swapping is OK" flag until the next reschedule
* call or context switch. It doesn't need to be tracked per
* thread because if the thread gets preempted for whatever
* reason the scheduler will make the same decision anyway.
*/
_current_cpu->swap_ok = preempt_ok;
#endif /* CONFIG_SMP */
}
static struct _cpu *thread_active_elsewhere(struct k_thread *thread)
{
/* Returns pointer to _cpu if the thread is currently running on
* another CPU. There are more scalable designs to answer this
* question in constant time, but this is fine for now.
*/
#ifdef CONFIG_SMP
int currcpu = _current_cpu->id;
unsigned int num_cpus = arch_num_cpus();
for (int i = 0; i < num_cpus; i++) {
if ((i != currcpu) &&
(_kernel.cpus[i].current == thread)) {
return &_kernel.cpus[i];
}
}
#endif /* CONFIG_SMP */
ARG_UNUSED(thread);
return NULL;
}
static void ready_thread(struct k_thread *thread)
{
#ifdef CONFIG_KERNEL_COHERENCE
__ASSERT_NO_MSG(arch_mem_coherent(thread));
#endif /* CONFIG_KERNEL_COHERENCE */
/* If thread is queued already, do not try and added it to the
* run queue again
*/
if (!z_is_thread_queued(thread) && z_is_thread_ready(thread)) {
SYS_PORT_TRACING_OBJ_FUNC(k_thread, sched_ready, thread);
queue_thread(thread);
update_cache(0);
flag_ipi(ipi_mask_create(thread));
}
}
void z_ready_thread(struct k_thread *thread)
{
K_SPINLOCK(&_sched_spinlock) {
if (thread_active_elsewhere(thread) == NULL) {
ready_thread(thread);
}
}
}
void z_move_thread_to_end_of_prio_q(struct k_thread *thread)
{
K_SPINLOCK(&_sched_spinlock) {
move_thread_to_end_of_prio_q(thread);
}
}
void z_sched_start(struct k_thread *thread)
{
k_spinlock_key_t key = k_spin_lock(&_sched_spinlock);
if (z_has_thread_started(thread)) {
k_spin_unlock(&_sched_spinlock, key);
return;
}
z_mark_thread_as_started(thread);
ready_thread(thread);
z_reschedule(&_sched_spinlock, key);
}
/* Spins in ISR context, waiting for a thread known to be running on
* another CPU to catch the IPI we sent and halt. Note that we check
* for ourselves being asynchronously halted first to prevent simple
* deadlocks (but not complex ones involving cycles of 3+ threads!).
* Acts to release the provided lock before returning.
*/
static void thread_halt_spin(struct k_thread *thread, k_spinlock_key_t key)
{
if (is_halting(_current)) {
halt_thread(_current,
is_aborting(_current) ? _THREAD_DEAD : _THREAD_SUSPENDED);
}
k_spin_unlock(&_sched_spinlock, key);
while (is_halting(thread)) {
unsigned int k = arch_irq_lock();
arch_spin_relax(); /* Requires interrupts be masked */
arch_irq_unlock(k);
}
}
/* Shared handler for k_thread_{suspend,abort}(). Called with the
* scheduler lock held and the key passed (which it may
* release/reacquire!) which will be released before a possible return
* (aborting _current will not return, obviously), which may be after
* a context switch.
*/
static void z_thread_halt(struct k_thread *thread, k_spinlock_key_t key,
bool terminate)
{
_wait_q_t *wq = &thread->join_queue;
#ifdef CONFIG_SMP
wq = terminate ? wq : &thread->halt_queue;
#endif
/* If the target is a thread running on another CPU, flag and
* poke (note that we might spin to wait, so a true
* synchronous IPI is needed here, not deferred!), it will
* halt itself in the IPI. Otherwise it's unscheduled, so we
* can clean it up directly.
*/
struct _cpu *cpu = thread_active_elsewhere(thread);
if (cpu != NULL) {
thread->base.thread_state |= (terminate ? _THREAD_ABORTING
: _THREAD_SUSPENDING);
#if defined(CONFIG_SMP) && defined(CONFIG_SCHED_IPI_SUPPORTED)
#ifdef CONFIG_ARCH_HAS_DIRECTED_IPIS
arch_sched_directed_ipi(IPI_CPU_MASK(cpu->id));
#else
arch_sched_broadcast_ipi();
#endif
#endif
if (arch_is_in_isr()) {
thread_halt_spin(thread, key);
} else {
add_to_waitq_locked(_current, wq);
z_swap(&_sched_spinlock, key);
}
} else {
halt_thread(thread, terminate ? _THREAD_DEAD : _THREAD_SUSPENDED);
if ((thread == _current) && !arch_is_in_isr()) {
z_swap(&_sched_spinlock, key);
__ASSERT(!terminate, "aborted _current back from dead");
} else {
k_spin_unlock(&_sched_spinlock, key);
}
}
/* NOTE: the scheduler lock has been released. Don't put
* logic here, it's likely to be racy/deadlocky even if you
* re-take the lock!
*/
}
void z_impl_k_thread_suspend(k_tid_t thread)
{
SYS_PORT_TRACING_OBJ_FUNC_ENTER(k_thread, suspend, thread);
(void)z_abort_thread_timeout(thread);
k_spinlock_key_t key = k_spin_lock(&_sched_spinlock);
if ((thread->base.thread_state & _THREAD_SUSPENDED) != 0U) {
/* The target thread is already suspended. Nothing to do. */
k_spin_unlock(&_sched_spinlock, key);
return;
}
z_thread_halt(thread, key, false);
SYS_PORT_TRACING_OBJ_FUNC_EXIT(k_thread, suspend, thread);
}
#ifdef CONFIG_USERSPACE
static inline void z_vrfy_k_thread_suspend(k_tid_t thread)
{
K_OOPS(K_SYSCALL_OBJ(thread, K_OBJ_THREAD));
z_impl_k_thread_suspend(thread);
}
#include <zephyr/syscalls/k_thread_suspend_mrsh.c>
#endif /* CONFIG_USERSPACE */
void z_impl_k_thread_resume(k_tid_t thread)
{
SYS_PORT_TRACING_OBJ_FUNC_ENTER(k_thread, resume, thread);
k_spinlock_key_t key = k_spin_lock(&_sched_spinlock);
/* Do not try to resume a thread that was not suspended */
if (!z_is_thread_suspended(thread)) {
k_spin_unlock(&_sched_spinlock, key);
return;
}
z_mark_thread_as_not_suspended(thread);
ready_thread(thread);
z_reschedule(&_sched_spinlock, key);
SYS_PORT_TRACING_OBJ_FUNC_EXIT(k_thread, resume, thread);
}
#ifdef CONFIG_USERSPACE
static inline void z_vrfy_k_thread_resume(k_tid_t thread)
{
K_OOPS(K_SYSCALL_OBJ(thread, K_OBJ_THREAD));
z_impl_k_thread_resume(thread);
}
#include <zephyr/syscalls/k_thread_resume_mrsh.c>
#endif /* CONFIG_USERSPACE */
static void unready_thread(struct k_thread *thread)
{
if (z_is_thread_queued(thread)) {
dequeue_thread(thread);
}
update_cache(thread == _current);
}
/* _sched_spinlock must be held */
static void add_to_waitq_locked(struct k_thread *thread, _wait_q_t *wait_q)
{
unready_thread(thread);
z_mark_thread_as_pending(thread);
SYS_PORT_TRACING_FUNC(k_thread, sched_pend, thread);
if (wait_q != NULL) {
thread->base.pended_on = wait_q;
_priq_wait_add(&wait_q->waitq, thread);
}
}
static void add_thread_timeout(struct k_thread *thread, k_timeout_t timeout)
{
if (!K_TIMEOUT_EQ(timeout, K_FOREVER)) {
z_add_thread_timeout(thread, timeout);
}
}
static void pend_locked(struct k_thread *thread, _wait_q_t *wait_q,
k_timeout_t timeout)
{
#ifdef CONFIG_KERNEL_COHERENCE
__ASSERT_NO_MSG(wait_q == NULL || arch_mem_coherent(wait_q));
#endif /* CONFIG_KERNEL_COHERENCE */
add_to_waitq_locked(thread, wait_q);
add_thread_timeout(thread, timeout);
}
void z_pend_thread(struct k_thread *thread, _wait_q_t *wait_q,
k_timeout_t timeout)
{
__ASSERT_NO_MSG(thread == _current || is_thread_dummy(thread));
K_SPINLOCK(&_sched_spinlock) {
pend_locked(thread, wait_q, timeout);
}
}
void z_unpend_thread_no_timeout(struct k_thread *thread)
{
K_SPINLOCK(&_sched_spinlock) {
if (thread->base.pended_on != NULL) {
unpend_thread_no_timeout(thread);
}
}
}
void z_sched_wake_thread(struct k_thread *thread, bool is_timeout)
{
K_SPINLOCK(&_sched_spinlock) {
bool killed = (thread->base.thread_state &
(_THREAD_DEAD | _THREAD_ABORTING));
#ifdef CONFIG_EVENTS
bool do_nothing = thread->no_wake_on_timeout && is_timeout;
thread->no_wake_on_timeout = false;
if (do_nothing) {
continue;
}
#endif /* CONFIG_EVENTS */
if (!killed) {
/* The thread is not being killed */
if (thread->base.pended_on != NULL) {
unpend_thread_no_timeout(thread);
}
z_mark_thread_as_started(thread);
if (is_timeout) {
z_mark_thread_as_not_suspended(thread);
}
ready_thread(thread);
}
}
}
#ifdef CONFIG_SYS_CLOCK_EXISTS
/* Timeout handler for *_thread_timeout() APIs */
void z_thread_timeout(struct _timeout *timeout)
{
struct k_thread *thread = CONTAINER_OF(timeout,
struct k_thread, base.timeout);
z_sched_wake_thread(thread, true);
}
#endif /* CONFIG_SYS_CLOCK_EXISTS */
int z_pend_curr(struct k_spinlock *lock, k_spinlock_key_t key,
_wait_q_t *wait_q, k_timeout_t timeout)
{
#if defined(CONFIG_TIMESLICING) && defined(CONFIG_SWAP_NONATOMIC)
pending_current = _current;
#endif /* CONFIG_TIMESLICING && CONFIG_SWAP_NONATOMIC */
__ASSERT_NO_MSG(sizeof(_sched_spinlock) == 0 || lock != &_sched_spinlock);
/* We do a "lock swap" prior to calling z_swap(), such that
* the caller's lock gets released as desired. But we ensure
* that we hold the scheduler lock and leave local interrupts
* masked until we reach the context switch. z_swap() itself
* has similar code; the duplication is because it's a legacy
* API that doesn't expect to be called with scheduler lock
* held.
*/
(void) k_spin_lock(&_sched_spinlock);
pend_locked(_current, wait_q, timeout);
k_spin_release(lock);
return z_swap(&_sched_spinlock, key);
}
struct k_thread *z_unpend1_no_timeout(_wait_q_t *wait_q)
{
struct k_thread *thread = NULL;
K_SPINLOCK(&_sched_spinlock) {
thread = _priq_wait_best(&wait_q->waitq);
if (thread != NULL) {
unpend_thread_no_timeout(thread);
}
}
return thread;
}
void z_unpend_thread(struct k_thread *thread)
{
z_unpend_thread_no_timeout(thread);
(void)z_abort_thread_timeout(thread);
}
/* Priority set utility that does no rescheduling, it just changes the
* run queue state, returning true if a reschedule is needed later.
*/
bool z_thread_prio_set(struct k_thread *thread, int prio)
{
bool need_sched = 0;
int old_prio = thread->base.prio;
K_SPINLOCK(&_sched_spinlock) {
need_sched = z_is_thread_ready(thread);
if (need_sched) {
if (!IS_ENABLED(CONFIG_SMP) || z_is_thread_queued(thread)) {
dequeue_thread(thread);
thread->base.prio = prio;
queue_thread(thread);
if (old_prio > prio) {
flag_ipi(ipi_mask_create(thread));
}
} else {
/*
* This is a running thread on SMP. Update its
* priority, but do not requeue it. An IPI is
* needed if the priority is both being lowered
* and it is running on another CPU.
*/
thread->base.prio = prio;
struct _cpu *cpu;
cpu = thread_active_elsewhere(thread);
if ((cpu != NULL) && (old_prio < prio)) {
flag_ipi(IPI_CPU_MASK(cpu->id));
}
}
update_cache(1);
} else {
thread->base.prio = prio;
}
}
SYS_PORT_TRACING_OBJ_FUNC(k_thread, sched_priority_set, thread, prio);
return need_sched;
}
static inline bool resched(uint32_t key)
{
#ifdef CONFIG_SMP
_current_cpu->swap_ok = 0;
#endif /* CONFIG_SMP */
return arch_irq_unlocked(key) && !arch_is_in_isr();
}
/*
* Check if the next ready thread is the same as the current thread
* and save the trip if true.
*/
static inline bool need_swap(void)
{
/* the SMP case will be handled in C based z_swap() */
#ifdef CONFIG_SMP
return true;
#else
struct k_thread *new_thread;
/* Check if the next ready thread is the same as the current thread */
new_thread = _kernel.ready_q.cache;
return new_thread != _current;
#endif /* CONFIG_SMP */
}
void z_reschedule(struct k_spinlock *lock, k_spinlock_key_t key)
{
if (resched(key.key) && need_swap()) {
z_swap(lock, key);
} else {
k_spin_unlock(lock, key);
signal_pending_ipi();
}
}
void z_reschedule_irqlock(uint32_t key)
{
if (resched(key) && need_swap()) {
z_swap_irqlock(key);
} else {
irq_unlock(key);
signal_pending_ipi();
}
}
void k_sched_lock(void)
{
K_SPINLOCK(&_sched_spinlock) {
SYS_PORT_TRACING_FUNC(k_thread, sched_lock);
z_sched_lock();
}
}
void k_sched_unlock(void)
{
K_SPINLOCK(&_sched_spinlock) {
__ASSERT(_current->base.sched_locked != 0U, "");
__ASSERT(!arch_is_in_isr(), "");
++_current->base.sched_locked;
update_cache(0);
}
LOG_DBG("scheduler unlocked (%p:%d)",
_current, _current->base.sched_locked);
SYS_PORT_TRACING_FUNC(k_thread, sched_unlock);
z_reschedule_unlocked();
}
struct k_thread *z_swap_next_thread(void)
{
#ifdef CONFIG_SMP
struct k_thread *ret = next_up();
if (ret == _current) {
/* When not swapping, have to signal IPIs here. In
* the context switch case it must happen later, after
* _current gets requeued.
*/
signal_pending_ipi();
}
return ret;
#else
return _kernel.ready_q.cache;
#endif /* CONFIG_SMP */
}
#ifdef CONFIG_USE_SWITCH
/* Just a wrapper around _current = xxx with tracing */
static inline void set_current(struct k_thread *new_thread)
{
z_thread_mark_switched_out();
_current_cpu->current = new_thread;
}
/**
* @brief Determine next thread to execute upon completion of an interrupt
*
* Thread preemption is performed by context switching after the completion
* of a non-recursed interrupt. This function determines which thread to
* switch to if any. This function accepts as @p interrupted either:
*
* - The handle for the interrupted thread in which case the thread's context
* must already be fully saved and ready to be picked up by a different CPU.
*
* - NULL if more work is required to fully save the thread's state after
* it is known that a new thread is to be scheduled. It is up to the caller
* to store the handle resulting from the thread that is being switched out
* in that thread's "switch_handle" field after its
* context has fully been saved, following the same requirements as with
* the @ref arch_switch() function.
*
* If a new thread needs to be scheduled then its handle is returned.
* Otherwise the same value provided as @p interrupted is returned back.
* Those handles are the same opaque types used by the @ref arch_switch()
* function.
*
* @warning
* The _current value may have changed after this call and not refer
* to the interrupted thread anymore. It might be necessary to make a local
* copy before calling this function.
*
* @param interrupted Handle for the thread that was interrupted or NULL.
* @retval Handle for the next thread to execute, or @p interrupted when
* no new thread is to be scheduled.
*/
void *z_get_next_switch_handle(void *interrupted)
{
z_check_stack_sentinel();
#ifdef CONFIG_SMP
void *ret = NULL;
K_SPINLOCK(&_sched_spinlock) {
struct k_thread *old_thread = _current, *new_thread;
if (IS_ENABLED(CONFIG_SMP)) {
old_thread->switch_handle = NULL;
}
new_thread = next_up();
z_sched_usage_switch(new_thread);
if (old_thread != new_thread) {
uint8_t cpu_id;
update_metairq_preempt(new_thread);
z_sched_switch_spin(new_thread);
arch_cohere_stacks(old_thread, interrupted, new_thread);
_current_cpu->swap_ok = 0;
cpu_id = arch_curr_cpu()->id;
new_thread->base.cpu = cpu_id;
set_current(new_thread);
#ifdef CONFIG_TIMESLICING
z_reset_time_slice(new_thread);
#endif /* CONFIG_TIMESLICING */
#ifdef CONFIG_SPIN_VALIDATE
/* Changed _current! Update the spinlock
* bookkeeping so the validation doesn't get
* confused when the "wrong" thread tries to
* release the lock.
*/
z_spin_lock_set_owner(&_sched_spinlock);
#endif /* CONFIG_SPIN_VALIDATE */
/* A queued (runnable) old/current thread
* needs to be added back to the run queue
* here, and atomically with its switch handle
* being set below. This is safe now, as we
* will not return into it.
*/
if (z_is_thread_queued(old_thread)) {
#ifdef CONFIG_SCHED_IPI_CASCADE
if ((new_thread->base.cpu_mask != -1) &&
(old_thread->base.cpu_mask != BIT(cpu_id))) {
flag_ipi(ipi_mask_create(old_thread));
}
#endif
runq_add(old_thread);
}
}
old_thread->switch_handle = interrupted;
ret = new_thread->switch_handle;
if (IS_ENABLED(CONFIG_SMP)) {
/* Active threads MUST have a null here */
new_thread->switch_handle = NULL;
}
}
signal_pending_ipi();
return ret;
#else
z_sched_usage_switch(_kernel.ready_q.cache);
_current->switch_handle = interrupted;
set_current(_kernel.ready_q.cache);
return _current->switch_handle;
#endif /* CONFIG_SMP */
}
#endif /* CONFIG_USE_SWITCH */
int z_unpend_all(_wait_q_t *wait_q)
{
int need_sched = 0;
struct k_thread *thread;
for (thread = z_waitq_head(wait_q); thread != NULL; thread = z_waitq_head(wait_q)) {
z_unpend_thread(thread);
z_ready_thread(thread);
need_sched = 1;
}
return need_sched;
}
void init_ready_q(struct _ready_q *ready_q)
{
_priq_run_init(&ready_q->runq);
}
void z_sched_init(void)
{
#ifdef CONFIG_SCHED_CPU_MASK_PIN_ONLY
for (int i = 0; i < CONFIG_MP_MAX_NUM_CPUS; i++) {
init_ready_q(&_kernel.cpus[i].ready_q);
}
#else
init_ready_q(&_kernel.ready_q);
#endif /* CONFIG_SCHED_CPU_MASK_PIN_ONLY */
}
void z_impl_k_thread_priority_set(k_tid_t thread, int prio)
{
/*
* Use NULL, since we cannot know what the entry point is (we do not
* keep track of it) and idle cannot change its priority.
*/
Z_ASSERT_VALID_PRIO(prio, NULL);
bool need_sched = z_thread_prio_set((struct k_thread *)thread, prio);
if ((need_sched) && (IS_ENABLED(CONFIG_SMP) ||
(_current->base.sched_locked == 0U))) {
z_reschedule_unlocked();
}
}