sergiotarxz/nuttx
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity
09d5d05b95
nuttx/sched/wqueue/kwork_notifier.c

515 lines
15 KiB
C
Raw Blame History

/****************************************************************************
* sched/wqueue/kwork_notifier.c
*
* Copyright (C) 2018 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* 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 <nuttx/config.h>
#include <sys/types.h>
#include <stdint.h>
#include <stdbool.h>
#include <unistd.h>
#include <string.h>
#include <sched.h>
#include <assert.h>
#include <nuttx/kmalloc.h>
#include <nuttx/semaphore.h>
#include <nuttx/wqueue.h>
#include "signal/signal.h"
#ifdef CONFIG_WQUEUE_NOTIFIER
/****************************************************************************
* Private Types
****************************************************************************/
/* The full allocated notification will hold additional information. The
* allocated notification information persist until the work is executed
* and must be freed using kmm_free() by the work.
*/
struct work_notifier_alloc_s
{
struct work_notifier_s info; /* The notification info */
struct work_s work; /* Used for scheduling the work */
};
/* This structure describes one notification list entry */
struct work_notifier_entry_s
{
FAR struct work_notifier_entry_s *flink;
FAR struct work_notifier_alloc_s *alloc; /* Allocated notification info copy */
int16_t key; /* Unique ID for the notification */
};
/****************************************************************************
* Private Data
****************************************************************************/
/* This is a statically allocated pool of notification structures */
static struct work_notifier_entry_s
g_notifier_pool[CONFIG_WQUEUE_NOTIFIER_NWAITERS];
/* This is a list of free notification structures */
static FAR struct work_notifier_entry_s *g_notifier_free;
/* This is a singly linked list of pending notifications. When an event
* occurs available, *all* of the waiters for that event in this list will
* be signaled and the entry will be freed. If there are multiple waiters
* for some resource, then only the highest priority thread will get the
* resource. Lower priority threads will need to call work_notifier_setup()
* once again.
*/
static FAR struct work_notifier_entry_s *g_notifier_pending;
/* This semaphore is used as mutex to enforce mutually exclusive access to
* the notification data structures.
*/
static sem_t g_notifier_sem;
/* Used for lookup key generation */
static uint16_t g_notifier_key;
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: work_notifier_alloc
*
* Description:
* Allocate a notification structure by removing it from the free list.
*
****************************************************************************/
static FAR struct work_notifier_entry_s *work_notifier_alloc(void)
{
FAR struct work_notifier_entry_s *notifier;
notifier = g_notifier_free;
if (notifier != NULL)
{
g_notifier_free = notifier->flink;
notifier->flink = NULL;
}
return notifier;
}
/****************************************************************************
* Name: work_notifier_free
*
* Description:
* Free a notification structure by returning it to the head of the free
* list.
*
****************************************************************************/
static inline void
work_notifier_free(FAR struct work_notifier_entry_s *notifier)
{
notifier->flink = g_notifier_free;
g_notifier_free = notifier;
}
/****************************************************************************
* Name: work_notifier_find
*
* Description:
* Given a unique key for notification, find the corresponding notification
* structure in the pending notification list.
*
****************************************************************************/
static FAR struct work_notifier_entry_s *
work_notifier_find(int16_t key, FAR struct work_notifier_entry_s **pprev)
{
FAR struct work_notifier_entry_s *notifier;
FAR struct work_notifier_entry_s *prev;
/* Find the entry matching this key in the g_notifier_pending list. */
for (prev = NULL, notifier = g_notifier_pending;
notifier != NULL;
prev = notifier, notifier = notifier->flink)
{
/* Is this the one we were looking for? */
if (notifier->key == key)
{
/* Return the previous entry if so requested */
if (pprev != NULL)
{
*pprev = prev;
}
return notifier;
}
}
return NULL;
}
/****************************************************************************
* Name: work_notifier_key
*
* Description:
* Generate a unique key for this notification.
*
****************************************************************************/
static int16_t work_notifier_key(void)
{
int16_t key;
/* Loop until a unique key is generated */
do
{
if (g_notifier_key >= INT16_MAX)
{
g_notifier_key = 0;
}
key = (int16_t)++g_notifier_key;
}
while (work_notifier_find(key, NULL) != NULL);
return key;
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: work_notifier_initialize
*
* Description:
* Set up the notification data structures for normal operation.
*
****************************************************************************/
void work_notifier_initialize(void)
{
int i;
/* Add each notification structure to the free list */
for (i = 0; i < CONFIG_WQUEUE_NOTIFIER_NWAITERS; i++)
{
FAR struct work_notifier_entry_s *notifier = &g_notifier_pool[i];
/* Add the pre-allocated notification to the head of the free list */
notifier->flink = g_notifier_free;
g_notifier_free = notifier;
}
/* Initialize the semaphore that enforces mutually exclusive access to the
* notification data structures.
*/
nxsem_init(&g_notifier_sem, 0, 1);
}
/****************************************************************************
* Name: work_notifier_setup
*
* Description:
* Set up to provide a notification when event is signaled.
*
* Input Parameters:
* info - Describes the work notification.
*
* Returned Value:
* > 0 - The key which may be used later in a call to
* work_notifier_teardown().
* == 0 - Not used (reserved for wrapper functions).
* < 0 - An unexpected error occurred and no signal will be sent. The
* returned value is a negated errno value that indicates the
* nature of the failure.
*
****************************************************************************/
int work_notifier_setup(FAR struct work_notifier_s *info)
{
int ret;
/* Get exclusive access to the notifier data structures */
ret = nxsem_wait(&g_notifier_sem);
if (ret < 0)
{
return ret;
}
/* Allocate a new notification */
FAR struct work_notifier_entry_s *notifier = work_notifier_alloc();
if (notifier == NULL)
{
ret = -ENOSPC;
}
else
{
FAR struct work_notifier_alloc_s *alloc;
int16_t key;
/* Duplicate the notification info */
alloc = kmm_malloc(sizeof(struct work_notifier_alloc_s));
if (alloc == NULL)
{
work_notifier_free(notifier);
return -ENOMEM;
}
memcpy(&alloc->info, info, sizeof(struct work_notifier_s));
/* Generate a unique key for this notification */
key = work_notifier_key();
/* Add the notification to the head of the pending list
*
* REVISIT: Work will be processed in LIFO order. Perhaps
* we should should consider saving the notification is the
* order of the caller's execution priority so that the
* notifications executed in a saner order?
*/
notifier->flink = g_notifier_pending;
notifier->alloc = alloc;
notifier->key = key;
g_notifier_pending = notifier;
ret = key;
}
(void)nxsem_post(&g_notifier_sem);
return ret;
}
/****************************************************************************
* Name: work_notifier_teardown
*
* Description:
* Eliminate a notification previously setup by work_notifier_setup().
* This function should only be called if the notification should be
* aborted prior to the notification. The notification will automatically
* be torn down after the signal is sent.
*
* Input Parameters:
* key - The key value returned from a previous call to
* work_notifier_setup().
*
* Returned Value:
* Zero (OK) is returned on success; a negated errno value is returned on
* any failure.
*
****************************************************************************/
int work_notifier_teardown(int key)
{
FAR struct work_notifier_entry_s *notifier;
FAR struct work_notifier_entry_s *prev;
int ret;
/* Get exclusive access to the notifier data structures */
ret = nxsem_wait(&g_notifier_sem);
if (ret < 0)
{
return ret;
}
/* Find the entry matching this PID in the g_notifier_pending list. We
* assume that there is only one.
*/
notifier = work_notifier_find(key, &prev);
if (notifier == NULL)
{
/* There is no notification with this key in the pending list */
ret = -ENOENT;
}
else
{
/* Found it! Remove the notification from the pending list */
if (prev == NULL)
{
g_notifier_pending = notifier->flink;
}
else
{
prev->flink = notifier->flink;
}
/* Free the contained information */
DEBUGASSERT(notifier->alloc != NULL);
kmm_free(notifier->alloc);
/* And return the notification to the free list */
work_notifier_free(notifier);
ret = OK;
}
(void)nxsem_post(&g_notifier_sem);
return ret;
}
/****************************************************************************
* Name: work_notifier_signal
*
* Description:
* An event has just occurred. Signal all threads waiting for that event.
*
* When an event of interest occurs, *all* of the workers waiting for this
* event will be executed. If there are multiple workers for a resource
* then only the first to execute will get the resource. Others will
* need to call work_notifier_setup() once again.
*
* Input Parameters:
* evtype - The type of the event that just occurred.
* qualifier - Event qualifier to distinguish different cases of the
* generic event type.
*
* Returned Value:
* None.
*
****************************************************************************/
void work_notifier_signal(enum work_evtype_e evtype,
FAR void *qualifier)
{
FAR struct work_notifier_entry_s *notifier;
FAR struct work_notifier_entry_s *prev;
FAR struct work_notifier_entry_s *next;
int ret;
/* Get exclusive access to the notifier data structure */
ret = nxsem_wait(&g_notifier_sem);
while (ret < 0)
{
DEBUGASSERT(ret == -EINTR || ret == -ECANCELED);
}
/* Don't let any newly started threads block this thread until all of
* the notifications and been sent.
*/
sched_lock();
/* Process the notification at the head of the pending list until the
* pending list is empty */
/* Find the entry matching this key in the g_notifier_pending list. */
for (prev = NULL, notifier = g_notifier_pending;
notifier != NULL;
notifier = next)
{
FAR struct work_notifier_alloc_s *alloc;
FAR struct work_notifier_s *info;
/* Set up for the next time through the loop (in case the entry is
* removed from the list).
*/
next = notifier->flink;
/* Check if this is the a notification request for the event that
* just occurred.
*/
alloc = notifier->alloc;
DEBUGASSERT(alloc != NULL);
info = &alloc->info;
if (info->evtype == evtype && info->qualifier == qualifier)
{
/* Yes.. Remove the notification from the pending list */
if (prev == NULL)
{
g_notifier_pending = next;
}
else
{
prev->flink = next;
}
/* Schedule the work */
(void)work_queue(HPWORK, &alloc->work, info->worker, info, 0);
/* Free the notification by returning it to the free list */
work_notifier_free(notifier);
}
else
{
/* The entry was not removed, the current entry will be the
* next previous entry.
*/
prev = notifier;
}
}
sched_unlock();
(void)nxsem_post(&g_notifier_sem);
}
#endif /* CONFIG_WQUEUE_NOTIFIER */
Reference in New Issue View Git Blame Copy Permalink