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>
171 lines
5.1 KiB
C
171 lines
5.1 KiB
C
/****************************************************************************
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* sched/wqueue/wqueue.h
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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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#ifndef __SCHED_WQUEUE_WQUEUE_H
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#define __SCHED_WQUEUE_WQUEUE_H
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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 <semaphore.h>
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#include <sys/types.h>
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#include <stdbool.h>
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#include <nuttx/clock.h>
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#include <nuttx/queue.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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/* Kernel thread names */
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#define HPWORKNAME "hpwork"
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#define LPWORKNAME "lpwork"
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/****************************************************************************
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* Public Type Definitions
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****************************************************************************/
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/* This represents one worker */
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struct kworker_s
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{
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pid_t pid; /* The task ID of the worker thread */
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};
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/* This structure defines the state of one kernel-mode work queue */
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struct kwork_wqueue_s
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{
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struct dq_queue_s q; /* The queue of pending work */
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sem_t sem; /* The counting semaphore of the wqueue */
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struct kworker_s worker[1]; /* Describes a worker thread */
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};
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/* This structure defines the state of one high-priority work queue. This
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* structure must be cast-compatible with kwork_wqueue_s.
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*/
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#ifdef CONFIG_SCHED_HPWORK
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struct hp_wqueue_s
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{
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struct dq_queue_s q; /* The queue of pending work */
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sem_t sem; /* The counting semaphore of the wqueue */
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/* Describes each thread in the high priority queue's thread pool */
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struct kworker_s worker[CONFIG_SCHED_HPNTHREADS];
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};
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#endif
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/* This structure defines the state of one low-priority work queue. This
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* structure must be cast compatible with kwork_wqueue_s
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*/
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#ifdef CONFIG_SCHED_LPWORK
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struct lp_wqueue_s
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{
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struct dq_queue_s q; /* The queue of pending work */
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sem_t sem; /* The counting semaphore of the wqueue */
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/* Describes each thread in the low priority queue's thread pool */
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struct kworker_s worker[CONFIG_SCHED_LPNTHREADS];
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};
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#endif
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/****************************************************************************
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* Public Data
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****************************************************************************/
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#ifdef CONFIG_SCHED_HPWORK
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/* The state of the kernel mode, high priority work queue. */
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extern struct hp_wqueue_s g_hpwork;
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#endif
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#ifdef CONFIG_SCHED_LPWORK
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/* The state of the kernel mode, low priority work queue(s). */
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extern struct lp_wqueue_s g_lpwork;
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#endif
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/****************************************************************************
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* Public Function Prototypes
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****************************************************************************/
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/****************************************************************************
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* Name: work_start_highpri
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*
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* Description:
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* Start the high-priority, kernel-mode work queue.
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*
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* Input Parameters:
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* None
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*
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* Returned Value:
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* The task ID of the worker thread is returned on success. A negated
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* errno value is returned on failure.
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*
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****************************************************************************/
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#ifdef CONFIG_SCHED_HPWORK
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int work_start_highpri(void);
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#endif
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/****************************************************************************
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* Name: work_start_lowpri
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*
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* Description:
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* Start the low-priority, kernel-mode worker thread(s)
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*
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* Input Parameters:
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* None
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*
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* Returned Value:
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* The task ID of the worker thread is returned on success. A negated
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* errno value is returned on failure.
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*
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****************************************************************************/
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#ifdef CONFIG_SCHED_LPWORK
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int work_start_lowpri(void);
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#endif
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/****************************************************************************
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* Name: work_initialize_notifier
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*
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* Description:
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* Set up the notification data structures for normal operation.
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*
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****************************************************************************/
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#ifdef CONFIG_WQUEUE_NOTIFIER
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void work_initialize_notifier(void);
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#endif
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#endif /* CONFIG_SCHED_WORKQUEUE */
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#endif /* __SCHED_WQUEUE_WQUEUE_H */
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