blob: 682ee79593aa3f02f9500d4aed42058e8e4dced9 [file] [log] [blame]
/*
* Copyright (c) 2017 Wind River Systems, Inc.
*
* SPDX-License-Identifier: Apache-2.0
*/
/**
* @file
*
* @brief Kernel asynchronous event polling interface.
*
* This polling mechanism allows waiting on multiple events concurrently,
* either events triggered directly, or from kernel objects or other kernel
* constructs.
*/
#include <kernel.h>
#include <kernel_structs.h>
#include <kernel_internal.h>
#include <wait_q.h>
#include <ksched.h>
#include <syscall_handler.h>
#include <misc/slist.h>
#include <misc/dlist.h>
#include <misc/util.h>
#include <misc/__assert.h>
#include <stdbool.h>
/* Single subsystem lock. Locking per-event would be better on highly
* contended SMP systems, but the original locking scheme here is
* subtle (it relies on releasing/reacquiring the lock in areas for
* latency control and it's sometimes hard to see exactly what data is
* "inside" a given critical section). Do the synchronization port
* later as an optimization.
*/
static struct k_spinlock lock;
void k_poll_event_init(struct k_poll_event *event, u32_t type,
int mode, void *obj)
{
__ASSERT(mode == K_POLL_MODE_NOTIFY_ONLY,
"only NOTIFY_ONLY mode is supported\n");
__ASSERT(type < (BIT(_POLL_NUM_TYPES)), "invalid type\n");
__ASSERT(obj != NULL, "must provide an object\n");
event->poller = NULL;
/* event->tag is left uninitialized: the user will set it if needed */
event->type = type;
event->state = K_POLL_STATE_NOT_READY;
event->mode = mode;
event->unused = 0U;
event->obj = obj;
}
/* must be called with interrupts locked */
static inline bool is_condition_met(struct k_poll_event *event, u32_t *state)
{
switch (event->type) {
case K_POLL_TYPE_SEM_AVAILABLE:
if (k_sem_count_get(event->sem) > 0) {
*state = K_POLL_STATE_SEM_AVAILABLE;
return true;
}
break;
case K_POLL_TYPE_DATA_AVAILABLE:
if (!k_queue_is_empty(event->queue)) {
*state = K_POLL_STATE_FIFO_DATA_AVAILABLE;
return true;
}
break;
case K_POLL_TYPE_SIGNAL:
if (event->signal->signaled != 0U) {
*state = K_POLL_STATE_SIGNALED;
return true;
}
break;
case K_POLL_TYPE_IGNORE:
break;
default:
__ASSERT(false, "invalid event type (0x%x)\n", event->type);
break;
}
return false;
}
static inline void add_event(sys_dlist_t *events, struct k_poll_event *event,
struct _poller *poller)
{
struct k_poll_event *pending;
pending = (struct k_poll_event *)sys_dlist_peek_tail(events);
if ((pending == NULL) ||
z_is_t1_higher_prio_than_t2(pending->poller->thread,
poller->thread)) {
sys_dlist_append(events, &event->_node);
return;
}
SYS_DLIST_FOR_EACH_CONTAINER(events, pending, _node) {
if (z_is_t1_higher_prio_than_t2(poller->thread,
pending->poller->thread)) {
sys_dlist_insert(&pending->_node, &event->_node);
return;
}
}
sys_dlist_append(events, &event->_node);
}
/* must be called with interrupts locked */
static inline int register_event(struct k_poll_event *event,
struct _poller *poller)
{
switch (event->type) {
case K_POLL_TYPE_SEM_AVAILABLE:
__ASSERT(event->sem != NULL, "invalid semaphore\n");
add_event(&event->sem->poll_events, event, poller);
break;
case K_POLL_TYPE_DATA_AVAILABLE:
__ASSERT(event->queue != NULL, "invalid queue\n");
add_event(&event->queue->poll_events, event, poller);
break;
case K_POLL_TYPE_SIGNAL:
__ASSERT(event->signal != NULL, "invalid poll signal\n");
add_event(&event->signal->poll_events, event, poller);
break;
case K_POLL_TYPE_IGNORE:
/* nothing to do */
break;
default:
__ASSERT(false, "invalid event type\n");
break;
}
event->poller = poller;
return 0;
}
/* must be called with interrupts locked */
static inline void clear_event_registration(struct k_poll_event *event)
{
bool remove = false;
event->poller = NULL;
switch (event->type) {
case K_POLL_TYPE_SEM_AVAILABLE:
__ASSERT(event->sem != NULL, "invalid semaphore\n");
remove = true;
break;
case K_POLL_TYPE_DATA_AVAILABLE:
__ASSERT(event->queue != NULL, "invalid queue\n");
remove = true;
break;
case K_POLL_TYPE_SIGNAL:
__ASSERT(event->signal != NULL, "invalid poll signal\n");
remove = true;
break;
case K_POLL_TYPE_IGNORE:
/* nothing to do */
break;
default:
__ASSERT(false, "invalid event type\n");
break;
}
if (remove && sys_dnode_is_linked(&event->_node)) {
sys_dlist_remove(&event->_node);
}
}
/* must be called with interrupts locked */
static inline void clear_event_registrations(struct k_poll_event *events,
int last_registered,
k_spinlock_key_t key)
{
for (; last_registered >= 0; last_registered--) {
clear_event_registration(&events[last_registered]);
k_spin_unlock(&lock, key);
key = k_spin_lock(&lock);
}
}
static inline void set_event_ready(struct k_poll_event *event, u32_t state)
{
event->poller = NULL;
event->state |= state;
}
int z_impl_k_poll(struct k_poll_event *events, int num_events, s32_t timeout)
{
__ASSERT(!z_is_in_isr(), "");
__ASSERT(events != NULL, "NULL events\n");
__ASSERT(num_events > 0, "zero events\n");
int last_registered = -1, rc;
k_spinlock_key_t key;
struct _poller poller = { .thread = _current, .is_polling = true, };
/* find events whose condition is already fulfilled */
for (int ii = 0; ii < num_events; ii++) {
u32_t state;
key = k_spin_lock(&lock);
if (is_condition_met(&events[ii], &state)) {
set_event_ready(&events[ii], state);
poller.is_polling = false;
} else if (timeout != K_NO_WAIT && poller.is_polling) {
rc = register_event(&events[ii], &poller);
if (rc == 0) {
++last_registered;
} else {
__ASSERT(false, "unexpected return code\n");
}
}
k_spin_unlock(&lock, key);
}
key = k_spin_lock(&lock);
/*
* If we're not polling anymore, it means that at least one event
* condition is met, either when looping through the events here or
* because one of the events registered has had its state changed.
*/
if (!poller.is_polling) {
clear_event_registrations(events, last_registered, key);
k_spin_unlock(&lock, key);
return 0;
}
poller.is_polling = false;
if (timeout == K_NO_WAIT) {
k_spin_unlock(&lock, key);
return -EAGAIN;
}
_wait_q_t wait_q = Z_WAIT_Q_INIT(&wait_q);
int swap_rc = z_pend_curr(&lock, key, &wait_q, timeout);
/*
* Clear all event registrations. If events happen while we're in this
* loop, and we already had one that triggered, that's OK: they will
* end up in the list of events that are ready; if we timed out, and
* events happen while we're in this loop, that is OK as well since
* we've already know the return code (-EAGAIN), and even if they are
* added to the list of events that occurred, the user has to check the
* return code first, which invalidates the whole list of event states.
*/
key = k_spin_lock(&lock);
clear_event_registrations(events, last_registered, key);
k_spin_unlock(&lock, key);
return swap_rc;
}
#ifdef CONFIG_USERSPACE
Z_SYSCALL_HANDLER(k_poll, events, num_events, timeout)
{
int ret;
k_spinlock_key_t key;
struct k_poll_event *events_copy = NULL;
unsigned int bounds;
/* Validate the events buffer and make a copy of it in an
* allocated kernel-side buffer.
*/
if (Z_SYSCALL_VERIFY(num_events > 0)) {
ret = -EINVAL;
goto out;
}
if (Z_SYSCALL_VERIFY_MSG(
!__builtin_umul_overflow(num_events,
sizeof(struct k_poll_event),
&bounds),
"num_events too large")) {
ret = -EINVAL;
goto out;
}
events_copy = z_thread_malloc(bounds);
if (!events_copy) {
ret = -ENOMEM;
goto out;
}
key = k_spin_lock(&lock);
if (Z_SYSCALL_MEMORY_WRITE(events, bounds)) {
k_spin_unlock(&lock, key);
goto oops_free;
}
(void)memcpy(events_copy, (void *)events, bounds);
k_spin_unlock(&lock, key);
/* Validate what's inside events_copy */
for (int i = 0; i < num_events; i++) {
struct k_poll_event *e = &events_copy[i];
if (Z_SYSCALL_VERIFY(e->mode == K_POLL_MODE_NOTIFY_ONLY)) {
ret = -EINVAL;
goto out_free;
}
switch (e->type) {
case K_POLL_TYPE_IGNORE:
break;
case K_POLL_TYPE_SIGNAL:
Z_OOPS(Z_SYSCALL_OBJ(e->signal, K_OBJ_POLL_SIGNAL));
break;
case K_POLL_TYPE_SEM_AVAILABLE:
Z_OOPS(Z_SYSCALL_OBJ(e->sem, K_OBJ_SEM));
break;
case K_POLL_TYPE_DATA_AVAILABLE:
Z_OOPS(Z_SYSCALL_OBJ(e->queue, K_OBJ_QUEUE));
break;
default:
ret = -EINVAL;
goto out_free;
}
}
ret = k_poll(events_copy, num_events, timeout);
(void)memcpy((void *)events, events_copy, bounds);
out_free:
k_free(events_copy);
out:
return ret;
oops_free:
k_free(events_copy);
Z_OOPS(1);
}
#endif
/* must be called with interrupts locked */
static int signal_poll_event(struct k_poll_event *event, u32_t state)
{
if (!event->poller) {
goto ready_event;
}
struct k_thread *thread = event->poller->thread;
__ASSERT(event->poller->thread != NULL,
"poller should have a thread\n");
event->poller->is_polling = false;
if (!z_is_thread_pending(thread)) {
goto ready_event;
}
if (z_is_thread_timeout_expired(thread)) {
return -EAGAIN;
}
z_unpend_thread(thread);
z_set_thread_return_value(thread,
state == K_POLL_STATE_CANCELLED ? -EINTR : 0);
if (!z_is_thread_ready(thread)) {
goto ready_event;
}
z_ready_thread(thread);
ready_event:
set_event_ready(event, state);
return 0;
}
void z_handle_obj_poll_events(sys_dlist_t *events, u32_t state)
{
struct k_poll_event *poll_event;
poll_event = (struct k_poll_event *)sys_dlist_get(events);
if (poll_event != NULL) {
(void) signal_poll_event(poll_event, state);
}
}
void z_impl_k_poll_signal_init(struct k_poll_signal *signal)
{
sys_dlist_init(&signal->poll_events);
signal->signaled = 0U;
/* signal->result is left unitialized */
z_object_init(signal);
}
#ifdef CONFIG_USERSPACE
Z_SYSCALL_HANDLER(k_poll_signal_init, signal)
{
Z_OOPS(Z_SYSCALL_OBJ_INIT(signal, K_OBJ_POLL_SIGNAL));
z_impl_k_poll_signal_init((struct k_poll_signal *)signal);
return 0;
}
#endif
void z_impl_k_poll_signal_check(struct k_poll_signal *signal,
unsigned int *signaled, int *result)
{
*signaled = signal->signaled;
*result = signal->result;
}
#ifdef CONFIG_USERSPACE
Z_SYSCALL_HANDLER(k_poll_signal_check, signal, signaled, result)
{
Z_OOPS(Z_SYSCALL_OBJ(signal, K_OBJ_POLL_SIGNAL));
Z_OOPS(Z_SYSCALL_MEMORY_WRITE(signaled, sizeof(unsigned int)));
Z_OOPS(Z_SYSCALL_MEMORY_WRITE(result, sizeof(int)));
z_impl_k_poll_signal_check((struct k_poll_signal *)signal,
(unsigned int *)signaled, (int *)result);
return 0;
}
#endif
int z_impl_k_poll_signal_raise(struct k_poll_signal *signal, int result)
{
k_spinlock_key_t key = k_spin_lock(&lock);
struct k_poll_event *poll_event;
signal->result = result;
signal->signaled = 1U;
poll_event = (struct k_poll_event *)sys_dlist_get(&signal->poll_events);
if (poll_event == NULL) {
k_spin_unlock(&lock, key);
return 0;
}
int rc = signal_poll_event(poll_event, K_POLL_STATE_SIGNALED);
z_reschedule(&lock, key);
return rc;
}
#ifdef CONFIG_USERSPACE
Z_SYSCALL_HANDLER(k_poll_signal_raise, signal, result)
{
Z_OOPS(Z_SYSCALL_OBJ(signal, K_OBJ_POLL_SIGNAL));
return z_impl_k_poll_signal_raise((struct k_poll_signal *)signal, result);
}
Z_SYSCALL_HANDLER1_SIMPLE_VOID(k_poll_signal_reset, K_OBJ_POLL_SIGNAL,
struct k_poll_signal *);
#endif