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/****************************************************************************
* net/iob/iob_free.c
*
* Copyright (C) 2014 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>
#if defined(CONFIG_DEBUG) && defined(CONFIG_NET_IOB_DEBUG)
/* Force debug output (from this file only) */
# undef CONFIG_DEBUG_NET
# define CONFIG_DEBUG_NET 1
#endif
#include <semaphore.h>
#include <assert.h>
#include <debug.h>
#include <nuttx/arch.h>
#include <nuttx/net/iob.h>
#include "iob.h"
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/****************************************************************************
* Private Types
****************************************************************************/
/****************************************************************************
* Private Data
****************************************************************************/
/****************************************************************************
* Public Data
****************************************************************************/
/****************************************************************************
* 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)
{
FAR struct iob_s *next = iob->io_flink;
irqstate_t flags;
nllvdbg("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)
{
/* 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 next entry is last entry in the
* chain... and if it is empty
*/
next->io_pktlen = 0;
DEBUGASSERT(next->io_len == 0 && next->io_flink == NULL);
}
nllvdbg("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 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 = irqsave();
iob->io_flink = g_iob_freelist;
g_iob_freelist = iob;
/* Signal that an IOB is available */
sem_post(&g_iob_sem);
irqrestore(flags);
/* And return the I/O buffer after the one that was freed */
return next;
}
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