97 lines
3.2 KiB
C
97 lines
3.2 KiB
C
/****************************************************************************
|
|
* mm/iob/iob_free_qentry.c
|
|
*
|
|
* Licensed to the Apache Software Foundation (ASF) under one or more
|
|
* contributor license agreements. See the NOTICE file distributed with
|
|
* this work for additional information regarding copyright ownership. The
|
|
* ASF licenses this file to you under the Apache License, Version 2.0 (the
|
|
* "License"); you may not use this file except in compliance with the
|
|
* License. You may obtain a copy of the License at
|
|
*
|
|
* http://www.apache.org/licenses/LICENSE-2.0
|
|
*
|
|
* Unless required by applicable law or agreed to in writing, software
|
|
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
|
|
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
|
|
* License for the specific language governing permissions and limitations
|
|
* under the License.
|
|
*
|
|
****************************************************************************/
|
|
|
|
/****************************************************************************
|
|
* Included Files
|
|
****************************************************************************/
|
|
|
|
#include <nuttx/config.h>
|
|
|
|
#include <assert.h>
|
|
|
|
#include <nuttx/irq.h>
|
|
#include <nuttx/arch.h>
|
|
#include <nuttx/mm/iob.h>
|
|
|
|
#include "iob.h"
|
|
|
|
#if CONFIG_IOB_NCHAINS > 0
|
|
|
|
/****************************************************************************
|
|
* Public Functions
|
|
****************************************************************************/
|
|
|
|
/****************************************************************************
|
|
* Name: iob_free_qentry
|
|
*
|
|
* Description:
|
|
* Free the I/O buffer chain container by returning it to the free list.
|
|
* The link to the next I/O buffer in the chain is return.
|
|
*
|
|
****************************************************************************/
|
|
|
|
FAR struct iob_qentry_s *iob_free_qentry(FAR struct iob_qentry_s *iobq)
|
|
{
|
|
FAR struct iob_qentry_s *nextq = iobq->qe_flink;
|
|
irqstate_t flags;
|
|
|
|
/* Free the I/O buffer chain container by adding it to the head of the
|
|
* free or the committed list. We don't know what context we are called
|
|
* from so we use extreme measures to protect the free list: We disable
|
|
* interrupts very briefly.
|
|
*/
|
|
|
|
flags = spin_lock_irqsave(&g_iob_lock);
|
|
|
|
/* Which list? If there is a task waiting for an IOB chain, then put
|
|
* the IOB chain on either the free list or on the committed list where
|
|
* it is reserved for that allocation (and not available to
|
|
* iob_tryalloc_qentry()).
|
|
*/
|
|
|
|
if (g_qentry_sem.semcount < 0)
|
|
{
|
|
iobq->qe_flink = g_iob_qcommitted;
|
|
g_iob_qcommitted = iobq;
|
|
}
|
|
else
|
|
{
|
|
iobq->qe_flink = g_iob_freeqlist;
|
|
g_iob_freeqlist = iobq;
|
|
}
|
|
|
|
spin_unlock_irqrestore(&g_iob_lock, flags);
|
|
|
|
/* Signal that an I/O buffer chain container is available. If there
|
|
* is a thread waiting for an I/O buffer chain container, this will
|
|
* wake up exactly one thread. The semaphore count will correctly
|
|
* indicated that the awakened task owns an I/O buffer chain container
|
|
* and should find it in the committed list.
|
|
*/
|
|
|
|
nxsem_post(&g_qentry_sem);
|
|
|
|
/* And return the I/O buffer chain container after the one that was freed */
|
|
|
|
return nextq;
|
|
}
|
|
|
|
#endif /* CONFIG_IOB_NCHAINS > 0 */
|