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- /****************************************************************************
- * mm/iob/iob_free.c
- *
- * Copyright (C) 2014, 2016-2018 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 <stdbool.h>
- #include <semaphore.h>
- #include <assert.h>
- #include <debug.h>
- #include <nuttx/irq.h>
- #include <nuttx/arch.h>
- #include <nuttx/mm/iob.h>
- #include "iob.h"
- /****************************************************************************
- * Pre-processor Definitions
- ****************************************************************************/
- #ifdef CONFIG_IOB_NOTIFIER
- # if !defined(CONFIG_IOB_NOTIFIER_DIV) || CONFIG_IOB_NOTIFIER_DIV < 2
- # define IOB_DIVIDER 1
- # elif CONFIG_IOB_NOTIFIER_DIV < 4
- # define IOB_DIVIDER 2
- # elif CONFIG_IOB_NOTIFIER_DIV < 8
- # define IOB_DIVIDER 4
- # elif CONFIG_IOB_NOTIFIER_DIV < 16
- # define IOB_DIVIDER 8
- # elif CONFIG_IOB_NOTIFIER_DIV < 32
- # define IOB_DIVIDER 16
- # elif CONFIG_IOB_NOTIFIER_DIV < 64
- # define IOB_DIVIDER 32
- # else
- # define IOB_DIVIDER 64
- # endif
- #endif
- #define IOB_MASK (IOB_DIVIDER - 1)
- /****************************************************************************
- * Public Functions
- ****************************************************************************/
- /****************************************************************************
- * Name: iob_free
- *
- * Description:
- * Free the I/O buffer at the head of a buffer chain returning it to the
- * free list. The link to the next I/O buffer in the chain is return.
- *
- ****************************************************************************/
- FAR struct iob_s *iob_free(FAR struct iob_s *iob,
- enum iob_user_e producerid)
- {
- FAR struct iob_s *next = iob->io_flink;
- irqstate_t flags;
- #ifdef CONFIG_IOB_NOTIFIER
- int16_t navail;
- #endif
- iobinfo("iob=%p io_pktlen=%u io_len=%u next=%p\n",
- iob, iob->io_pktlen, iob->io_len, next);
- /* Copy the data that only exists in the head of a I/O buffer chain into
- * the next entry.
- */
- if (next != NULL)
- {
- /* Copy and decrement the total packet length, being careful to
- * do nothing too crazy.
- */
- if (iob->io_pktlen > iob->io_len)
- {
- /* Adjust packet length and move it to the next entry */
- next->io_pktlen = iob->io_pktlen - iob->io_len;
- DEBUGASSERT(next->io_pktlen >= next->io_len);
- }
- else
- {
- /* This can only happen if the free entry isn't first entry in the
- * chain...
- */
- next->io_pktlen = 0;
- }
- iobinfo("next=%p io_pktlen=%u io_len=%u\n",
- next, next->io_pktlen, next->io_len);
- }
- /* Free the I/O buffer 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, then put
- * the IOB on either the free list or on the committed list where
- * it is reserved for that allocation (and not available to
- * iob_tryalloc()).
- */
- if (g_iob_sem.semcount < 0)
- {
- iob->io_flink = g_iob_committed;
- g_iob_committed = iob;
- }
- else
- {
- iob->io_flink = g_iob_freelist;
- g_iob_freelist = iob;
- }
- /* Signal that an IOB is available. If there is a thread blocked,
- * waiting for an IOB, this will wake up exactly one thread. The
- * semaphore count will correctly indicated that the awakened task
- * owns an IOB and should find it in the committed list.
- */
- nxsem_post(&g_iob_sem);
- DEBUGASSERT(g_iob_sem.semcount <= CONFIG_IOB_NBUFFERS);
- #if !defined(CONFIG_DISABLE_MOUNTPOINT) && defined(CONFIG_FS_PROCFS) && \
- defined(CONFIG_MM_IOB) && !defined(CONFIG_FS_PROCFS_EXCLUDE_IOBINFO)
- iob_stats_onfree(producerid);
- #endif
- #if CONFIG_IOB_THROTTLE > 0
- nxsem_post(&g_throttle_sem);
- DEBUGASSERT(g_throttle_sem.semcount <= (CONFIG_IOB_NBUFFERS - CONFIG_IOB_THROTTLE));
- #endif
- #ifdef CONFIG_IOB_NOTIFIER
- /* Check if the IOB was claimed by a thread that is blocked waiting
- * for an IOB.
- */
- navail = iob_navail(false);
- if (navail > 0 && (navail & IOB_MASK) == 0)
- {
- /* Signal any threads that have requested a signal notification
- * when an IOB becomes available.
- */
- iob_notifier_signal();
- }
- #endif
- leave_critical_section(flags);
- /* And return the I/O buffer after the one that was freed */
- return next;
- }
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