/**************************************************************************** * libc/wqueue/work_process.c * * Copyright (C) 2009-2014 Gregory Nutt. All rights reserved. * Author: Gregory Nutt * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in * the documentation and/or other materials provided with the * distribution. * 3. Neither the name NuttX nor the names of its contributors may be * used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. * ****************************************************************************/ /**************************************************************************** * Included Files ****************************************************************************/ #include #include #include #include #include #include #include #ifdef CONFIG_SCHED_WORKQUEUE /**************************************************************************** * Pre-processor Definitions ****************************************************************************/ /* Use CLOCK_MONOTONIC if it is available. CLOCK_REALTIME can cause bad * delays if the time is changed. */ #ifdef CONFIG_CLOCK_MONOTONIC # define WORK_CLOCK CLOCK_MONOTONIC #else # define WORK_CLOCK CLOCK_REALTIME #endif /* The work poll period is in system ticks. */ #define WORKPERIOD_TICKS (CONFIG_SCHED_WORKPERIOD / USEC_PER_TICK) /**************************************************************************** * Private Type Declarations ****************************************************************************/ /**************************************************************************** * Public Data ****************************************************************************/ /**************************************************************************** * Private Data ****************************************************************************/ /**************************************************************************** * Private Functions ****************************************************************************/ /**************************************************************************** * Public Functions ****************************************************************************/ /**************************************************************************** * Name: work_process * * Description: * This is the logic that performs actions placed on any work list. This * logic is the common underlying logic to all work queues. This logic is * part of the internal implementation of each work queue; it should not * be called from application level logic. * * Input parameters: * wqueue - Describes the work queue to be processed * * Returned Value: * None * ****************************************************************************/ void work_process(FAR struct wqueue_s *wqueue) { volatile FAR struct work_s *work; worker_t worker; irqstate_t flags; FAR void *arg; uint32_t elapsed; uint32_t remaining; uint32_t stick; uint32_t ctick; uint32_t next; /* Then process queued work. We need to keep interrupts disabled while * we process items in the work list. */ next = WORKPERIOD_TICKS; flags = irqsave(); /* Get the time that we started this polling cycle in clock ticks. */ stick = clock_systimer(); /* And check each entry in the work queue. Since we have disabled * interrupts we know: (1) we will not be suspended unless we do * so ourselves, and (2) there will be no changes to the work queue */ work = (FAR struct work_s *)wqueue->q.head; while (work) { DEBUGASSERT(wqueue->wq_sem.count > 0); /* Is this work ready? It is ready if there is no delay or if * the delay has elapsed. qtime is the time that the work was added * to the work queue. It will always be greater than or equal to * zero. Therefore a delay of zero will always execute immediately. */ ctick = clock_systimer(); elapsed = ctick - work->qtime; if (elapsed >= work->delay) { /* Remove the ready-to-execute work from the list */ (void)dq_rem((struct dq_entry_s *)work, &wqueue->q); /* Extract the work description from the entry (in case the work * instance by the re-used after it has been de-queued). */ worker = work->worker; /* Check for a race condition where the work may be nullified * before it is removed from the queue. */ if (worker != NULL) { /* Extract the work argument (before re-enabling interrupts) */ arg = work->arg; /* Mark the work as no longer being queued */ work->worker = NULL; /* Do the work. Re-enable interrupts while the work is being * performed... we don't have any idea how long that will take! */ irqrestore(flags); worker(arg); /* Now, unfortunately, since we re-enabled interrupts we don't * know the state of the work list and we will have to start * back at the head of the list. */ flags = irqsave(); work = (FAR struct work_s *)wqueue->q.head; } else { /* Cancelled.. Just move to the next work in the list with * interrupts still disabled. */ work = (FAR struct work_s *)work->dq.flink; } } else { /* This one is not ready.. will it be ready before the next * scheduled wakeup interval? * * NOTE that elapsed is relative to the the current time, * not the time of beginning of this queue processing pass. * So it may need an adjustment. */ elapsed += (ctick - stick); remaining = elapsed - work->delay; if (remaining < next) { /* Yes.. Then schedule to wake up when the work is ready */ next = remaining; } /* Then try the next in the list. */ work = (FAR struct work_s *)work->dq.flink; } } /* There is no work to be performed now. Check if we need to delay or if we have * already exceed the duration of the polling period. */ if (next < WORKPERIOD_TICKS) { /* Wait awhile to check the work list. We will wait here until either * the time elapses or until we are awakened by a signal. Interrupts * will be re-enabled while we wait. */ usleep(next * USEC_PER_TICK); } irqrestore(flags); } #endif /* CONFIG_SCHED_WORKQUEUE */