/* * Copyright (c) 2017 Wind River Systems, Inc. * Copyright (c) 2023 Arm Limited (or its affiliates). All rights reserved. * * 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 #include #include #include #include #include #include #include #include #include /* 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; enum POLL_MODE { MODE_NONE, MODE_POLL, MODE_TRIGGERED }; static int signal_poller(struct k_poll_event *event, uint32_t state); static int signal_triggered_work(struct k_poll_event *event, uint32_t status); void k_poll_event_init(struct k_poll_event *event, uint32_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; SYS_PORT_TRACING_FUNC(k_poll_api, event_init, event); } /* must be called with interrupts locked */ static inline bool is_condition_met(struct k_poll_event *event, uint32_t *state) { switch (event->type) { case K_POLL_TYPE_SEM_AVAILABLE: if (k_sem_count_get(event->sem) > 0U) { *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_MSGQ_DATA_AVAILABLE: if (event->msgq->used_msgs > 0) { *state = K_POLL_STATE_MSGQ_DATA_AVAILABLE; return true; } break; #ifdef CONFIG_PIPES case K_POLL_TYPE_PIPE_DATA_AVAILABLE: if (k_pipe_read_avail(event->pipe)) { *state = K_POLL_STATE_PIPE_DATA_AVAILABLE; return true; } #endif /* CONFIG_PIPES */ case K_POLL_TYPE_IGNORE: break; default: __ASSERT(false, "invalid event type (0x%x)\n", event->type); break; } return false; } static struct k_thread *poller_thread(struct z_poller *p) { return p ? CONTAINER_OF(p, struct k_thread, poller) : NULL; } static inline void add_event(sys_dlist_t *events, struct k_poll_event *event, struct z_poller *poller) { struct k_poll_event *pending; pending = (struct k_poll_event *)sys_dlist_peek_tail(events); if ((pending == NULL) || (z_sched_prio_cmp(poller_thread(pending->poller), poller_thread(poller)) > 0)) { sys_dlist_append(events, &event->_node); return; } SYS_DLIST_FOR_EACH_CONTAINER(events, pending, _node) { if (z_sched_prio_cmp(poller_thread(poller), poller_thread(pending->poller)) > 0) { sys_dlist_insert(&pending->_node, &event->_node); return; } } sys_dlist_append(events, &event->_node); } /* must be called with interrupts locked */ static inline void register_event(struct k_poll_event *event, struct z_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_MSGQ_DATA_AVAILABLE: __ASSERT(event->msgq != NULL, "invalid message queue\n"); add_event(&event->msgq->poll_events, event, poller); break; #ifdef CONFIG_PIPES case K_POLL_TYPE_PIPE_DATA_AVAILABLE: __ASSERT(event->pipe != NULL, "invalid pipe\n"); add_event(&event->pipe->poll_events, event, poller); break; #endif /* CONFIG_PIPES */ case K_POLL_TYPE_IGNORE: /* nothing to do */ break; default: __ASSERT(false, "invalid event type\n"); break; } event->poller = poller; } /* must be called with interrupts locked */ static inline void clear_event_registration(struct k_poll_event *event) { bool remove_event = false; event->poller = NULL; switch (event->type) { case K_POLL_TYPE_SEM_AVAILABLE: __ASSERT(event->sem != NULL, "invalid semaphore\n"); remove_event = true; break; case K_POLL_TYPE_DATA_AVAILABLE: __ASSERT(event->queue != NULL, "invalid queue\n"); remove_event = true; break; case K_POLL_TYPE_SIGNAL: __ASSERT(event->signal != NULL, "invalid poll signal\n"); remove_event = true; break; case K_POLL_TYPE_MSGQ_DATA_AVAILABLE: __ASSERT(event->msgq != NULL, "invalid message queue\n"); remove_event = true; break; #ifdef CONFIG_PIPES case K_POLL_TYPE_PIPE_DATA_AVAILABLE: __ASSERT(event->pipe != NULL, "invalid pipe\n"); remove_event = true; break; #endif /* CONFIG_PIPES */ case K_POLL_TYPE_IGNORE: /* nothing to do */ break; default: __ASSERT(false, "invalid event type\n"); break; } if (remove_event && 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 num_events, k_spinlock_key_t key) { while (num_events--) { clear_event_registration(&events[num_events]); k_spin_unlock(&lock, key); key = k_spin_lock(&lock); } } static inline void set_event_ready(struct k_poll_event *event, uint32_t state) { event->poller = NULL; event->state |= state; } static inline int register_events(struct k_poll_event *events, int num_events, struct z_poller *poller, bool just_check) { int events_registered = 0; for (int ii = 0; ii < num_events; ii++) { k_spinlock_key_t key; uint32_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 (!just_check && poller->is_polling) { register_event(&events[ii], poller); events_registered += 1; } else { /* Event is not one of those identified in is_condition_met() * catching non-polling events, or is marked for just check, * or not marked for polling. No action needed. */ ; } k_spin_unlock(&lock, key); } return events_registered; } static int signal_poller(struct k_poll_event *event, uint32_t state) { struct k_thread *thread = poller_thread(event->poller); __ASSERT(thread != NULL, "poller should have a thread\n"); if (!z_is_thread_pending(thread)) { return 0; } z_unpend_thread(thread); arch_thread_return_value_set(thread, state == K_POLL_STATE_CANCELLED ? -EINTR : 0); if (!z_is_thread_ready(thread)) { return 0; } z_ready_thread(thread); return 0; } int z_impl_k_poll(struct k_poll_event *events, int num_events, k_timeout_t timeout) { int events_registered; k_spinlock_key_t key; struct z_poller *poller = &_current->poller; poller->is_polling = true; poller->mode = MODE_POLL; __ASSERT(!arch_is_in_isr(), ""); __ASSERT(events != NULL, "NULL events\n"); __ASSERT(num_events >= 0, "<0 events\n"); SYS_PORT_TRACING_FUNC_ENTER(k_poll_api, poll, events); events_registered = register_events(events, num_events, poller, K_TIMEOUT_EQ(timeout, K_NO_WAIT)); 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, events_registered, key); k_spin_unlock(&lock, key); SYS_PORT_TRACING_FUNC_EXIT(k_poll_api, poll, events, 0); return 0; } poller->is_polling = false; if (K_TIMEOUT_EQ(timeout, K_NO_WAIT)) { k_spin_unlock(&lock, key); SYS_PORT_TRACING_FUNC_EXIT(k_poll_api, poll, events, -EAGAIN); return -EAGAIN; } static _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, events_registered, key); k_spin_unlock(&lock, key); SYS_PORT_TRACING_FUNC_EXIT(k_poll_api, poll, events, swap_rc); return swap_rc; } #ifdef CONFIG_USERSPACE static inline int z_vrfy_k_poll(struct k_poll_event *events, int num_events, k_timeout_t timeout) { int ret; k_spinlock_key_t key; struct k_poll_event *events_copy = NULL; uint32_t bounds; /* Validate the events buffer and make a copy of it in an * allocated kernel-side buffer. */ if (K_SYSCALL_VERIFY(num_events >= 0)) { ret = -EINVAL; goto out; } if (K_SYSCALL_VERIFY_MSG(!u32_mul_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 (K_SYSCALL_MEMORY_WRITE(events, bounds)) { k_spin_unlock(&lock, key); goto oops_free; } (void)memcpy(events_copy, 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 (K_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: K_OOPS(K_SYSCALL_OBJ(e->signal, K_OBJ_POLL_SIGNAL)); break; case K_POLL_TYPE_SEM_AVAILABLE: K_OOPS(K_SYSCALL_OBJ(e->sem, K_OBJ_SEM)); break; case K_POLL_TYPE_DATA_AVAILABLE: K_OOPS(K_SYSCALL_OBJ(e->queue, K_OBJ_QUEUE)); break; case K_POLL_TYPE_MSGQ_DATA_AVAILABLE: K_OOPS(K_SYSCALL_OBJ(e->msgq, K_OBJ_MSGQ)); break; #ifdef CONFIG_PIPES case K_POLL_TYPE_PIPE_DATA_AVAILABLE: K_OOPS(K_SYSCALL_OBJ(e->pipe, K_OBJ_PIPE)); break; #endif /* CONFIG_PIPES */ 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); K_OOPS(1); } #include #endif /* CONFIG_USERSPACE */ /* must be called with interrupts locked */ static int signal_poll_event(struct k_poll_event *event, uint32_t state) { struct z_poller *poller = event->poller; int retcode = 0; if (poller != NULL) { if (poller->mode == MODE_POLL) { retcode = signal_poller(event, state); } else if (poller->mode == MODE_TRIGGERED) { retcode = signal_triggered_work(event, state); } else { /* Poller is not poll or triggered mode. No action needed.*/ ; } poller->is_polling = false; if (retcode < 0) { return retcode; } } set_event_ready(event, state); return retcode; } void z_handle_obj_poll_events(sys_dlist_t *events, uint32_t state) { struct k_poll_event *poll_event; k_spinlock_key_t key = k_spin_lock(&lock); poll_event = (struct k_poll_event *)sys_dlist_get(events); if (poll_event != NULL) { (void) signal_poll_event(poll_event, state); } k_spin_unlock(&lock, key); } void z_impl_k_poll_signal_init(struct k_poll_signal *sig) { sys_dlist_init(&sig->poll_events); sig->signaled = 0U; /* signal->result is left uninitialized */ k_object_init(sig); SYS_PORT_TRACING_FUNC(k_poll_api, signal_init, sig); } #ifdef CONFIG_USERSPACE static inline void z_vrfy_k_poll_signal_init(struct k_poll_signal *sig) { K_OOPS(K_SYSCALL_OBJ_INIT(sig, K_OBJ_POLL_SIGNAL)); z_impl_k_poll_signal_init(sig); } #include #endif /* CONFIG_USERSPACE */ void z_impl_k_poll_signal_reset(struct k_poll_signal *sig) { sig->signaled = 0U; SYS_PORT_TRACING_FUNC(k_poll_api, signal_reset, sig); } void z_impl_k_poll_signal_check(struct k_poll_signal *sig, unsigned int *signaled, int *result) { *signaled = sig->signaled; *result = sig->result; SYS_PORT_TRACING_FUNC(k_poll_api, signal_check, sig); } #ifdef CONFIG_USERSPACE void z_vrfy_k_poll_signal_check(struct k_poll_signal *sig, unsigned int *signaled, int *result) { K_OOPS(K_SYSCALL_OBJ(sig, K_OBJ_POLL_SIGNAL)); K_OOPS(K_SYSCALL_MEMORY_WRITE(signaled, sizeof(unsigned int))); K_OOPS(K_SYSCALL_MEMORY_WRITE(result, sizeof(int))); z_impl_k_poll_signal_check(sig, signaled, result); } #include #endif /* CONFIG_USERSPACE */ int z_impl_k_poll_signal_raise(struct k_poll_signal *sig, int result) { k_spinlock_key_t key = k_spin_lock(&lock); struct k_poll_event *poll_event; sig->result = result; sig->signaled = 1U; poll_event = (struct k_poll_event *)sys_dlist_get(&sig->poll_events); if (poll_event == NULL) { k_spin_unlock(&lock, key); SYS_PORT_TRACING_FUNC(k_poll_api, signal_raise, sig, 0); return 0; } int rc = signal_poll_event(poll_event, K_POLL_STATE_SIGNALED); SYS_PORT_TRACING_FUNC(k_poll_api, signal_raise, sig, rc); z_reschedule(&lock, key); return rc; } #ifdef CONFIG_USERSPACE static inline int z_vrfy_k_poll_signal_raise(struct k_poll_signal *sig, int result) { K_OOPS(K_SYSCALL_OBJ(sig, K_OBJ_POLL_SIGNAL)); return z_impl_k_poll_signal_raise(sig, result); } #include static inline void z_vrfy_k_poll_signal_reset(struct k_poll_signal *sig) { K_OOPS(K_SYSCALL_OBJ(sig, K_OBJ_POLL_SIGNAL)); z_impl_k_poll_signal_reset(sig); } #include #endif /* CONFIG_USERSPACE */ static void triggered_work_handler(struct k_work *work) { struct k_work_poll *twork = CONTAINER_OF(work, struct k_work_poll, work); /* * If callback is not set, the k_work_poll_submit_to_queue() * already cleared event registrations. */ if (twork->poller.mode != MODE_NONE) { k_spinlock_key_t key; key = k_spin_lock(&lock); clear_event_registrations(twork->events, twork->num_events, key); k_spin_unlock(&lock, key); } /* Drop work ownership and execute real handler. */ twork->workq = NULL; twork->real_handler(work); } static void triggered_work_expiration_handler(struct _timeout *timeout) { struct k_work_poll *twork = CONTAINER_OF(timeout, struct k_work_poll, timeout); twork->poller.is_polling = false; twork->poll_result = -EAGAIN; k_work_submit_to_queue(twork->workq, &twork->work); } extern int z_work_submit_to_queue(struct k_work_q *queue, struct k_work *work); static int signal_triggered_work(struct k_poll_event *event, uint32_t status) { struct z_poller *poller = event->poller; struct k_work_poll *twork = CONTAINER_OF(poller, struct k_work_poll, poller); if (poller->is_polling && twork->workq != NULL) { struct k_work_q *work_q = twork->workq; z_abort_timeout(&twork->timeout); twork->poll_result = 0; z_work_submit_to_queue(work_q, &twork->work); } return 0; } static int triggered_work_cancel(struct k_work_poll *work, k_spinlock_key_t key) { /* Check if the work waits for event. */ if (work->poller.is_polling && work->poller.mode != MODE_NONE) { /* Remove timeout associated with the work. */ z_abort_timeout(&work->timeout); /* * Prevent work execution if event arrives while we will be * clearing registrations. */ work->poller.mode = MODE_NONE; /* Clear registrations and work ownership. */ clear_event_registrations(work->events, work->num_events, key); work->workq = NULL; return 0; } /* * If we reached here, the work is either being registered in * the k_work_poll_submit_to_queue(), executed or is pending. * Only in the last case we have a chance to cancel it, but * unfortunately there is no public API performing this task. */ return -EINVAL; } void k_work_poll_init(struct k_work_poll *work, k_work_handler_t handler) { SYS_PORT_TRACING_OBJ_FUNC_ENTER(k_work_poll, init, work); *work = (struct k_work_poll) {}; k_work_init(&work->work, triggered_work_handler); work->real_handler = handler; z_init_timeout(&work->timeout); SYS_PORT_TRACING_OBJ_FUNC_EXIT(k_work_poll, init, work); } int k_work_poll_submit_to_queue(struct k_work_q *work_q, struct k_work_poll *work, struct k_poll_event *events, int num_events, k_timeout_t timeout) { int events_registered; k_spinlock_key_t key; __ASSERT(work_q != NULL, "NULL work_q\n"); __ASSERT(work != NULL, "NULL work\n"); __ASSERT(events != NULL, "NULL events\n"); __ASSERT(num_events > 0, "zero events\n"); SYS_PORT_TRACING_FUNC_ENTER(k_work_poll, submit_to_queue, work_q, work, timeout); /* Take ownership of the work if it is possible. */ key = k_spin_lock(&lock); if (work->workq != NULL) { if (work->workq == work_q) { int retval; retval = triggered_work_cancel(work, key); if (retval < 0) { k_spin_unlock(&lock, key); SYS_PORT_TRACING_FUNC_EXIT(k_work_poll, submit_to_queue, work_q, work, timeout, retval); return retval; } } else { k_spin_unlock(&lock, key); SYS_PORT_TRACING_FUNC_EXIT(k_work_poll, submit_to_queue, work_q, work, timeout, -EADDRINUSE); return -EADDRINUSE; } } work->poller.is_polling = true; work->workq = work_q; work->poller.mode = MODE_NONE; k_spin_unlock(&lock, key); /* Save list of events. */ work->events = events; work->num_events = num_events; /* Clear result */ work->poll_result = -EINPROGRESS; /* Register events */ events_registered = register_events(events, num_events, &work->poller, false); key = k_spin_lock(&lock); if (work->poller.is_polling && !K_TIMEOUT_EQ(timeout, K_NO_WAIT)) { /* * Poller is still polling. * No event is ready and all are watched. */ __ASSERT(num_events == events_registered, "Some events were not registered!\n"); /* Setup timeout if such action is requested */ if (!K_TIMEOUT_EQ(timeout, K_FOREVER)) { z_add_timeout(&work->timeout, triggered_work_expiration_handler, timeout); } /* From now, any event will result in submitted work. */ work->poller.mode = MODE_TRIGGERED; k_spin_unlock(&lock, key); SYS_PORT_TRACING_FUNC_EXIT(k_work_poll, submit_to_queue, work_q, work, timeout, 0); return 0; } /* * The K_NO_WAIT timeout was specified or at least one event * was ready at registration time or changed state since * registration. Hopefully, the poller mode was not set, so * work was not submitted to workqueue. */ /* * If poller is still polling, no watched event occurred. This means * we reached here due to K_NO_WAIT timeout "expiration". */ if (work->poller.is_polling) { work->poller.is_polling = false; work->poll_result = -EAGAIN; } else { work->poll_result = 0; } /* Clear registrations. */ clear_event_registrations(events, events_registered, key); k_spin_unlock(&lock, key); /* Submit work. */ k_work_submit_to_queue(work_q, &work->work); SYS_PORT_TRACING_FUNC_EXIT(k_work_poll, submit_to_queue, work_q, work, timeout, 0); return 0; } int k_work_poll_submit(struct k_work_poll *work, struct k_poll_event *events, int num_events, k_timeout_t timeout) { SYS_PORT_TRACING_FUNC_ENTER(k_work_poll, submit, work, timeout); int ret = k_work_poll_submit_to_queue(&k_sys_work_q, work, events, num_events, timeout); SYS_PORT_TRACING_FUNC_EXIT(k_work_poll, submit, work, timeout, ret); return ret; } int k_work_poll_cancel(struct k_work_poll *work) { k_spinlock_key_t key; int retval; SYS_PORT_TRACING_FUNC_ENTER(k_work_poll, cancel, work); /* Check if the work was submitted. */ if (work == NULL || work->workq == NULL) { SYS_PORT_TRACING_FUNC_EXIT(k_work_poll, cancel, work, -EINVAL); return -EINVAL; } key = k_spin_lock(&lock); retval = triggered_work_cancel(work, key); k_spin_unlock(&lock, key); SYS_PORT_TRACING_FUNC_EXIT(k_work_poll, cancel, work, retval); return retval; }