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- /****************************************************************************
- * mm/iob/iob_free_qentry.c
- *
- * Copyright (C) 2014, 2016-2017 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 <semaphore.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 = enter_critical_section();
- /* 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;
- }
- /* 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);
- leave_critical_section(flags);
- /* And return the I/O buffer chain container after the one that was freed */
- return nextq;
- }
- #endif /* CONFIG_IOB_NCHAINS > 0 */
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