/****************************************************************************
* net/tcp/tcp_wrbuffer.c
*
* Copyright (C) 2007-2009, 2013-2014 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
* Jason Jiang <jasonj@live.cn>
*
* 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/net/netconfig.h>
#if defined(CONFIG_NET) && defined(CONFIG_NET_TCP) && defined(CONFIG_NET_TCP_WRITE_BUFFERS)
#if defined(CONFIG_DEBUG) && defined(CONFIG_NET_TCP_WRBUFFER_DEBUG)
/* Force debug output (from this file only) */
# undef CONFIG_DEBUG_NET
# define CONFIG_DEBUG_NET 1
#endif
#include <queue.h>
#include <semaphore.h>
#include <string.h>
#include <assert.h>
#include <debug.h>
#include <nuttx/net/iob.h>
#include <nuttx/net/tcp.h>
#include "tcp/tcp.h"
/****************************************************************************
* Private Types
****************************************************************************/
/* Package all globals used by this logic into a structure */
struct wrbuffer_s
{
/* The semaphore to protect the buffers */
sem_t sem;
/* This is the list of available write buffers */
sq_queue_t freebuffers;
/* These are the pre-allocated write buffers */
struct tcp_wrbuffer_s buffers[CONFIG_NET_TCP_NWRBCHAINS];
};
/****************************************************************************
* Private Data
****************************************************************************/
/* This is the state of the global write buffer resource */
static struct wrbuffer_s g_wrbuffer;
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Function: tcp_wrbuffer_initialize
*
* Description:
* Initialize the list of free write buffers
*
* Assumptions:
* Called once early initialization.
*
****************************************************************************/
void tcp_wrbuffer_initialize(void)
{
int i;
sq_init(&g_wrbuffer.freebuffers);
for (i = 0; i < CONFIG_NET_TCP_NWRBCHAINS; i++)
{
sq_addfirst(&g_wrbuffer.buffers[i].wb_node, &g_wrbuffer.freebuffers);
}
sem_init(&g_wrbuffer.sem, 0, CONFIG_NET_TCP_NWRBCHAINS);
}
/****************************************************************************
* Function: tcp_wrbuffer_alloc
*
* Description:
* Allocate a TCP write buffer by taking a pre-allocated buffer from
* the free list. This function is called from TCP logic when a buffer
* of TCP data is about to sent
*
* Input parameters:
* None
*
* Assumptions:
* Called from user logic with interrupts enabled.
*
****************************************************************************/
FAR struct tcp_wrbuffer_s *tcp_wrbuffer_alloc(void)
{
FAR struct tcp_wrbuffer_s *wrb;
/* We need to allocate two things: (1) A write buffer structure and (2)
* at least one I/O buffer to start the chain.
*
* Allocate the write buffer structure first then the IOBG. In order to
* avoid deadlocks, we will need to free the IOB first, then the write
* buffer
*/
DEBUGVERIFY(sem_wait(&g_wrbuffer.sem));
/* Now, we are guaranteed to have a write buffer structure reserved
* for us in the free list.
*/
wrb = (FAR struct tcp_wrbuffer_s *)sq_remfirst(&g_wrbuffer.freebuffers);
DEBUGASSERT(wrb);
memset(wrb, 0, sizeof(struct tcp_wrbuffer_s));
/* Now get the first I/O buffer for the write buffer structure */
wrb->wb_iob = iob_alloc(false);
if (!wrb->wb_iob)
{
ndbg("ERROR: Failed to allocate I/O buffer\n");
tcp_wrbuffer_release(wrb);
return NULL;
}
return wrb;
}
/****************************************************************************
* Function: tcp_wrbuffer_release
*
* Description:
* Release a TCP write buffer by returning the buffer to the free list.
* This function is called from user logic after it is consumed the
* buffered data.
*
* Assumptions:
* Called from interrupt level with interrupts disabled.
*
****************************************************************************/
void tcp_wrbuffer_release(FAR struct tcp_wrbuffer_s *wrb)
{
DEBUGASSERT(wrb && wrb->wb_iob);
/* To avoid deadlocks, we must following this ordering: Release the I/O
* buffer chain first, then the write buffer structure.
*/
iob_free_chain(wrb->wb_iob);
/* Then free the write buffer structure */
sq_addlast(&wrb->wb_node, &g_wrbuffer.freebuffers);
sem_post(&g_wrbuffer.sem);
}
#endif /* CONFIG_NET && CONFIG_NET_TCP && CONFIG_NET_TCP_WRITE_BUFFERS */
