391 lines
11 KiB
C
391 lines
11 KiB
C
/****************************************************************************
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* sched/wqueue/kwork_notifier.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 <sys/types.h>
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#include <stdint.h>
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#include <stdbool.h>
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#include <unistd.h>
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#include <string.h>
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#include <sched.h>
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#include <assert.h>
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#include <nuttx/kmalloc.h>
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#include <nuttx/wqueue.h>
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#include "wqueue/wqueue.h"
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#ifdef CONFIG_WQUEUE_NOTIFIER
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/****************************************************************************
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* Private Types
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****************************************************************************/
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/* This structure describes one notification list entry. It is cast-
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* compatible with struct work_notifier_s. This structure is an allocated
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* container for the user notification data. It is allocated because it
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* must persist until the work is executed.
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*/
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struct work_notifier_entry_s
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{
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/* This must appear at the beginning of the structure. A reference to
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* the struct work_notifier_entry_s instance must be cast-compatible with
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* struct dq_entry_s.
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*/
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struct work_s work; /* Used for scheduling the work */
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/* User notification information */
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struct work_notifier_s info; /* The notification info */
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/* Additional payload needed to manage the notification */
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uint32_t key; /* Unique ID for the notification */
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};
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/****************************************************************************
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* Private Data
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****************************************************************************/
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/* This is a doubly linked list of free notifications. */
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static dq_queue_t g_notifier_free;
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/* This is a doubly linked list of pending notifications. When an event
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* occurs available, *all* of the waiters for that event in this list will
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* be notified and the entry will be freed. If there are multiple waiters
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* for some resource, then only the first to execute thread will get the
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* resource. Lower priority threads will need to call work_notifier_setup()
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* once again.
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*/
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static dq_queue_t g_notifier_pending;
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/****************************************************************************
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* Private Functions
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****************************************************************************/
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/****************************************************************************
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* Name: work_notifier_find
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*
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* Description:
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* Given a unique key for notification, find the corresponding notification
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* structure in the pending notification list.
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*
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****************************************************************************/
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static FAR struct work_notifier_entry_s *work_notifier_find(uint32_t key)
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{
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FAR struct work_notifier_entry_s *notifier;
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FAR dq_entry_t *entry;
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/* Find the entry matching this key in the g_notifier_pending list. */
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for (entry = dq_peek(&g_notifier_pending);
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entry != NULL;
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entry = dq_next(entry))
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{
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notifier = (FAR struct work_notifier_entry_s *)entry;
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/* Is this the one we were looking for? */
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if (notifier->key == key)
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{
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/* Yes.. return a reference to it */
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return notifier;
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}
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}
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return NULL;
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}
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/****************************************************************************
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* Name: work_notifier_key
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*
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* Description:
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* Generate a unique key for this notification.
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*
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****************************************************************************/
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static uint32_t work_notifier_key(void)
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{
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static uint32_t notifier_key;
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if (++notifier_key == 0)
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{
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notifier_key = 1;
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}
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return notifier_key;
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}
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/****************************************************************************
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* Name: work_notifier_worker
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*
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* Description:
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* Forward to the real worker and free the notification.
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*
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****************************************************************************/
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static void work_notifier_worker(FAR void *arg)
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{
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FAR struct work_notifier_entry_s *notifier =
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(FAR struct work_notifier_entry_s *)arg;
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irqstate_t flags;
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/* Forward to the real worker */
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notifier->info.worker(notifier->info.arg);
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/* Disable interrupts very briefly. */
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flags = enter_critical_section();
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/* Put the notification to the free list */
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dq_addlast((FAR dq_entry_t *)notifier, &g_notifier_free);
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leave_critical_section(flags);
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}
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: work_notifier_setup
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*
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* Description:
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* Set up to provide a notification when an event occurs.
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*
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* Input Parameters:
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* info - Describes the work notification.
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*
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* Returned Value:
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* > 0 - The key which may be used later in a call to
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* work_notifier_teardown().
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* == 0 - Not used (reserved for wrapper functions).
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* < 0 - An unexpected error occurred and no notification will be sent.
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* The returned value is a negated errno value that indicates the
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* nature of the failure.
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*
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****************************************************************************/
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int work_notifier_setup(FAR struct work_notifier_s *info)
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{
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FAR struct work_notifier_entry_s *notifier;
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irqstate_t flags;
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int ret;
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DEBUGASSERT(info != NULL && info->worker != NULL);
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DEBUGASSERT(info->qid == HPWORK || info->qid == LPWORK);
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/* Disable interrupts very briefly. */
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flags = enter_critical_section();
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/* Try to get the entry from the free list */
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notifier = (FAR struct work_notifier_entry_s *)
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dq_remfirst(&g_notifier_free);
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leave_critical_section(flags);
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if (notifier == NULL)
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{
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/* Allocate a new notification entry */
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notifier = kmm_malloc(sizeof(struct work_notifier_entry_s));
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}
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if (notifier == NULL)
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{
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ret = -ENOMEM;
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}
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else
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{
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/* Initialize the work structure */
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memset(¬ifier->work, 0, sizeof(notifier->work));
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/* Duplicate the notification info */
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memcpy(¬ifier->info, info, sizeof(struct work_notifier_s));
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/* Disable interrupts very briefly. */
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flags = enter_critical_section();
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/* Generate a unique key for this notification */
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notifier->key = work_notifier_key();
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/* Add the notification to the tail of the pending list
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*
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* REVISIT: Work will be processed in FIFO order. Perhaps
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* we should should consider saving the notification is the
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* order of the caller's execution priority so that the
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* notifications executed in a saner order?
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*/
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dq_addlast((FAR dq_entry_t *)notifier, &g_notifier_pending);
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ret = notifier->key;
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leave_critical_section(flags);
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}
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return ret;
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}
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/****************************************************************************
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* Name: work_notifier_teardown
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*
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* Description:
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* Eliminate a notification previously setup by work_notifier_setup().
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* This function should only be called if the notification should be
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* aborted prior to the notification. The notification will automatically
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* be torn down after the notification executes.
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*
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* Input Parameters:
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* key - The key value returned from a previous call to
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* work_notifier_setup().
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*
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* Returned Value:
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* None.
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*
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****************************************************************************/
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void work_notifier_teardown(int key)
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{
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FAR struct work_notifier_entry_s *notifier;
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irqstate_t flags;
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/* Disable interrupts very briefly. */
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flags = enter_critical_section();
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/* Find the entry matching this PID in the g_notifier_pending list. We
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* assume that there is only one.
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*/
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notifier = work_notifier_find(key);
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if (notifier != NULL)
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{
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/* Found it! Remove the notification from the pending list */
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dq_rem((FAR dq_entry_t *)notifier, &g_notifier_pending);
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/* Put the notification to the free list */
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dq_addlast((FAR dq_entry_t *)notifier, &g_notifier_free);
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}
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leave_critical_section(flags);
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}
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/****************************************************************************
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* Name: work_notifier_signal
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*
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* Description:
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* An event has just occurred. Notify all threads waiting for that event.
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*
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* When an event of interest occurs, *all* of the workers waiting for this
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* event will be executed. If there are multiple workers for a resource
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* then only the first to execute will get the resource. Others will
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* need to call work_notifier_setup() once again.
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*
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* Input Parameters:
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* evtype - The type of the event that just occurred.
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* qualifier - Event qualifier to distinguish different cases of the
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* generic event type.
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*
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* Returned Value:
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* None.
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*
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****************************************************************************/
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void work_notifier_signal(enum work_evtype_e evtype,
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FAR void *qualifier)
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{
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FAR struct work_notifier_entry_s *notifier;
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FAR dq_entry_t *entry;
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FAR dq_entry_t *next;
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irqstate_t flags;
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/* Don't let any newly started threads block this thread until all of
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* the notifications and been sent.
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*/
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flags = enter_critical_section();
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/* Process the notification at the head of the pending list until the
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* pending list is empty
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*/
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for (entry = dq_peek(&g_notifier_pending);
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entry != NULL;
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entry = next)
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{
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FAR struct work_notifier_s *info;
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/* Set up for the next time through the loop (in case the entry is
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* removed from the list).
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*/
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next = entry->flink;
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/* Set up some convenience pointers */
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notifier = (FAR struct work_notifier_entry_s *)entry;
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info = ¬ifier->info;
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/* Check if this is the a notification request for the event that
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* just occurred.
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*/
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if (info->evtype == evtype && info->qualifier == qualifier)
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{
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/* Yes.. Remove the notification from the pending list */
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dq_rem((FAR dq_entry_t *)notifier, &g_notifier_pending);
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/* Schedule the work. The entire notifier entry is passed as an
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* argument to the work function because that function is
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* responsible for freeing the allocated memory.
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*/
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work_queue(info->qid, ¬ifier->work,
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work_notifier_worker, entry, 0);
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}
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}
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leave_critical_section(flags);
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}
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#endif /* CONFIG_WQUEUE_NOTIFIER */
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