c9a38f42f7
Decouple the semcount and the work queue length. Previous Problem: If a work is queued and cancelled in high priority threads (or queued by timer and cancelled by another high priority thread) before work_thread runs, the queue operation will mark work_thread as ready to run, but the cancel operation minus the semcount back to -1 and makes wqueue->q empty. Then the work_thread still runs, found empty queue, and wait sem again, then semcount becomes -2 (being minused by 1) This can be done multiple times, then semcount can become very small value. Test case to produce incorrect semcount: high_priority_task() { for (int i = 0; i < 10000; i++) { work_queue(LPWORK, &work, worker, NULL, 0); work_cancel(LPWORK, &work); usleep(1); } /* Now the g_lpwork.sem.semcount is a value near -10000 */ } With incorrect semcount, any queue operation when the work_thread is busy, will only increase semcount and push work into queue, but cannot trigger work_thread (semcount is negative but work_thread is not waiting), then there will be more and more works left in queue while the work_thread is waiting sem and cannot call them. Signed-off-by: Zhe Weng <wengzhe@xiaomi.com>
192 lines
5.7 KiB
C
192 lines
5.7 KiB
C
/****************************************************************************
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* sched/wqueue/kwork_queue.c
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <stdint.h>
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#include <assert.h>
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#include <errno.h>
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#include <nuttx/irq.h>
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#include <nuttx/arch.h>
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#include <nuttx/clock.h>
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#include <nuttx/queue.h>
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#include <nuttx/wqueue.h>
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#include "wqueue/wqueue.h"
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#ifdef CONFIG_SCHED_WORKQUEUE
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/****************************************************************************
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* Pre-processor Definitions
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****************************************************************************/
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#define queue_work(wqueue, work) \
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do \
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{ \
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int sem_count; \
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dq_addlast((FAR dq_entry_t *)(work), &(wqueue).q); \
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nxsem_get_value(&(wqueue).sem, &sem_count); \
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if (sem_count < 0) /* There are threads waiting for sem. */ \
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{ \
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nxsem_post(&(wqueue).sem); \
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} \
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} \
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while (0)
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/****************************************************************************
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* Private Functions
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****************************************************************************/
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/****************************************************************************
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* Name: hp_work_timer_expiry
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****************************************************************************/
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#ifdef CONFIG_SCHED_HPWORK
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static void hp_work_timer_expiry(wdparm_t arg)
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{
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irqstate_t flags = enter_critical_section();
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queue_work(g_hpwork, arg);
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leave_critical_section(flags);
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}
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#endif
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/****************************************************************************
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* Name: lp_work_timer_expiry
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****************************************************************************/
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#ifdef CONFIG_SCHED_LPWORK
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static void lp_work_timer_expiry(wdparm_t arg)
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{
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irqstate_t flags = enter_critical_section();
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queue_work(g_lpwork, arg);
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leave_critical_section(flags);
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}
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#endif
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: work_queue
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*
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* Description:
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* Queue kernel-mode work to be performed at a later time. All queued
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* work will be performed on the worker thread of execution (not the
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* caller's).
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*
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* The work structure is allocated and must be initialized to all zero by
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* the caller. Otherwise, the work structure is completely managed by the
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* work queue logic. The caller should never modify the contents of the
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* work queue structure directly. If work_queue() is called before the
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* previous work has been performed and removed from the queue, then any
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* pending work will be canceled and lost.
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*
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* Input Parameters:
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* qid - The work queue ID (index)
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* work - The work structure to queue
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* worker - The worker callback to be invoked. The callback will be
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* invoked on the worker thread of execution.
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* arg - The argument that will be passed to the worker callback when
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* int is invoked.
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* delay - Delay (in clock ticks) from the time queue until the worker
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* is invoked. Zero means to perform the work immediately.
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*
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* Returned Value:
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* Zero on success, a negated errno on failure
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*
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****************************************************************************/
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int work_queue(int qid, FAR struct work_s *work, worker_t worker,
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FAR void *arg, clock_t delay)
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{
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irqstate_t flags;
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int ret = OK;
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/* Interrupts are disabled so that this logic can be called from with
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* task logic or from interrupt handling logic.
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*/
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flags = enter_critical_section();
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/* Remove the entry from the timer and work queue. */
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if (work->worker != NULL)
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{
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work_cancel(qid, work);
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}
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/* Initialize the work structure. */
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work->worker = worker; /* Work callback. non-NULL means queued */
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work->arg = arg; /* Callback argument */
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/* Queue the new work */
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#ifdef CONFIG_SCHED_HPWORK
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if (qid == HPWORK)
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{
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/* Queue high priority work */
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if (!delay)
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{
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queue_work(g_hpwork, work);
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}
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else
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{
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wd_start(&work->u.timer, delay, hp_work_timer_expiry,
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(wdparm_t)work);
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}
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}
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else
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#endif
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#ifdef CONFIG_SCHED_LPWORK
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if (qid == LPWORK)
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{
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/* Queue low priority work */
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if (!delay)
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{
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queue_work(g_lpwork, work);
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}
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else
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{
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wd_start(&work->u.timer, delay, lp_work_timer_expiry,
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(wdparm_t)work);
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}
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}
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else
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#endif
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{
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ret = -EINVAL;
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}
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leave_critical_section(flags);
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return ret;
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}
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#endif /* CONFIG_SCHED_WORKQUEUE */
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