tcpip.c

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/*
 * Copyright (c) 2008-2014, Pedigree Developers
 *
 * Please see the CONTRIB file in the root of the source tree for a full
 * list of contributors.
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */
 
/*
 * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
 * All rights reserved.
 *
 * 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. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
 *
 * This file is part of the lwIP TCP/IP stack.
 *
 * Author: Adam Dunkels <adam@sics.se>
 *
 */
 
#include "lwip/opt.h"
 
#if !NO_SYS /* don't build if not configured for use in lwipopts.h */
 
#include "lwip/priv/tcpip_priv.h"
#include "lwip/sys.h"
#include "lwip/memp.h"
#include "lwip/mem.h"
#include "lwip/init.h"
#include "lwip/ip.h"
#include "lwip/pbuf.h"
#include "lwip/etharp.h"
#include "netif/ethernet.h"
 
#define TCPIP_MSG_VAR_REF(name)     API_VAR_REF(name)
#define TCPIP_MSG_VAR_DECLARE(name) API_VAR_DECLARE(struct tcpip_msg, name)
#define TCPIP_MSG_VAR_ALLOC(name)   API_VAR_ALLOC(struct tcpip_msg, MEMP_TCPIP_MSG_API, name, ERR_MEM)
#define TCPIP_MSG_VAR_FREE(name)    API_VAR_FREE(MEMP_TCPIP_MSG_API, name)
 
/* global variables */
static tcpip_init_done_fn tcpip_init_done;
static void *tcpip_init_done_arg;
static sys_mbox_t mbox;
static sys_thread_t tcpip_thread_handle;
static struct tcpip_msg tcpip_shutdown_msg;
enum tcpip_lifecycle_state {
  TCPIP_STATE_RUNNING = 0,
  TCPIP_STATE_STOPPING = 1,
  TCPIP_STATE_STOPPED = 2,
  TCPIP_STATE_FAILED = 3,
  TCPIP_STATE_INITIALIZING = 4
};
static u8_t tcpip_shutdown_state = TCPIP_STATE_STOPPED;
static u32_t tcpip_active_producers;
 
static int
tcpip_producer_enter(void)
{
  if (__atomic_load_n(&tcpip_shutdown_state, __ATOMIC_ACQUIRE) !=
      TCPIP_STATE_RUNNING) {
    return 0;
  }
 
  __atomic_add_fetch(&tcpip_active_producers, 1, __ATOMIC_ACQ_REL);
  if (__atomic_load_n(&tcpip_shutdown_state, __ATOMIC_ACQUIRE) !=
      TCPIP_STATE_RUNNING) {
    __atomic_sub_fetch(&tcpip_active_producers, 1, __ATOMIC_RELEASE);
    return 0;
  }
  return 1;
}
 
static void
tcpip_producer_leave(void)
{
  LWIP_ASSERT("tcpip producer admission underflow",
              __atomic_load_n(&tcpip_active_producers, __ATOMIC_RELAXED) != 0);
  __atomic_sub_fetch(&tcpip_active_producers, 1, __ATOMIC_RELEASE);
}
 
#if LWIP_TCPIP_CORE_LOCKING
sys_mutex_t lock_tcpip_core;
#endif /* LWIP_TCPIP_CORE_LOCKING */
 
#if LWIP_TIMERS
/* wait for a message, timeouts are processed while waiting */
#define TCPIP_MBOX_FETCH(mbox, msg) sys_timeouts_mbox_fetch(mbox, msg)
#else /* LWIP_TIMERS */
/* wait for a message with timers disabled (e.g. pass a timer-check trigger into tcpip_thread) */
#define TCPIP_MBOX_FETCH(mbox, msg) sys_mbox_fetch(mbox, msg)
#endif /* LWIP_TIMERS */
 
static void
tcpip_thread(void *arg)
{
  struct tcpip_msg *msg;
  LWIP_UNUSED_ARG(arg);
 
  while (__atomic_load_n(&tcpip_shutdown_state, __ATOMIC_ACQUIRE) ==
         TCPIP_STATE_INITIALIZING) {
    sys_msleep(1);
  }
  LWIP_ASSERT("tcpip_thread started outside running state",
              __atomic_load_n(&tcpip_shutdown_state, __ATOMIC_ACQUIRE) ==
                  TCPIP_STATE_RUNNING);
 
  if (tcpip_init_done != NULL) {
    tcpip_init_done(tcpip_init_done_arg);
  }
 
  LOCK_TCPIP_CORE();
  while (1) {                          /* MAIN Loop */
    UNLOCK_TCPIP_CORE();
    LWIP_TCPIP_THREAD_ALIVE();
    /* wait for a message, timeouts are processed while waiting */
    TCPIP_MBOX_FETCH(&mbox, (void **)&msg);
    LOCK_TCPIP_CORE();
    if (msg == NULL) {
      LWIP_DEBUGF(TCPIP_DEBUG, ("tcpip_thread: invalid message: NULL\n"));
      LWIP_ASSERT("tcpip_thread: invalid message", 0);
      continue;
    }
    switch (msg->type) {
#if !LWIP_TCPIP_CORE_LOCKING
    case TCPIP_MSG_API:
      LWIP_DEBUGF(TCPIP_DEBUG, ("tcpip_thread: API message %p\n", (void *)msg));
      msg->msg.api_msg.function(msg->msg.api_msg.msg);
      break;
    case TCPIP_MSG_API_CALL:
      LWIP_DEBUGF(TCPIP_DEBUG, ("tcpip_thread: API CALL message %p\n", (void *)msg));
      msg->msg.api_call.arg->err = msg->msg.api_call.function(msg->msg.api_call.arg);
      sys_sem_signal(msg->msg.api_call.sem);
      break;
#endif /* !LWIP_TCPIP_CORE_LOCKING */
 
#if !LWIP_TCPIP_CORE_LOCKING_INPUT
    case TCPIP_MSG_INPKT:
      LWIP_DEBUGF(TCPIP_DEBUG, ("tcpip_thread: PACKET %p\n", (void *)msg));
      msg->msg.inp.input_fn(msg->msg.inp.p, msg->msg.inp.netif);
      memp_free(MEMP_TCPIP_MSG_INPKT, msg);
      break;
#endif /* !LWIP_TCPIP_CORE_LOCKING_INPUT */
 
#if LWIP_TCPIP_TIMEOUT && LWIP_TIMERS
    case TCPIP_MSG_TIMEOUT:
      LWIP_DEBUGF(TCPIP_DEBUG, ("tcpip_thread: TIMEOUT %p\n", (void *)msg));
      sys_timeout(msg->msg.tmo.msecs, msg->msg.tmo.h, msg->msg.tmo.arg);
      memp_free(MEMP_TCPIP_MSG_API, msg);
      break;
    case TCPIP_MSG_UNTIMEOUT:
      LWIP_DEBUGF(TCPIP_DEBUG, ("tcpip_thread: UNTIMEOUT %p\n", (void *)msg));
      sys_untimeout(msg->msg.tmo.h, msg->msg.tmo.arg);
      memp_free(MEMP_TCPIP_MSG_API, msg);
      break;
#endif /* LWIP_TCPIP_TIMEOUT && LWIP_TIMERS */
 
    case TCPIP_MSG_CALLBACK:
      LWIP_DEBUGF(TCPIP_DEBUG, ("tcpip_thread: CALLBACK %p\n", (void *)msg));
      msg->msg.cb.function(msg->msg.cb.ctx);
      memp_free(MEMP_TCPIP_MSG_API, msg);
      break;
 
    case TCPIP_MSG_CALLBACK_STATIC:
      LWIP_DEBUGF(TCPIP_DEBUG, ("tcpip_thread: CALLBACK_STATIC %p\n", (void *)msg));
      msg->msg.cb.function(msg->msg.cb.ctx);
      break;
 
    case TCPIP_MSG_SHUTDOWN:
      UNLOCK_TCPIP_CORE();
      return;
 
    default:
      LWIP_DEBUGF(TCPIP_DEBUG, ("tcpip_thread: invalid message: %d\n", msg->type));
      LWIP_ASSERT("tcpip_thread: invalid message", 0);
      break;
    }
  }
}
 
err_t
tcpip_inpkt(struct pbuf *p, struct netif *inp, netif_input_fn input_fn)
{
  if (!tcpip_producer_enter()) {
    return ERR_CLSD;
  }
#if LWIP_TCPIP_CORE_LOCKING_INPUT
  err_t ret;
  LWIP_DEBUGF(TCPIP_DEBUG, ("tcpip_inpkt: PACKET %p/%p\n", (void *)p, (void *)inp));
  LOCK_TCPIP_CORE();
  ret = input_fn(p, inp);
  UNLOCK_TCPIP_CORE();
  tcpip_producer_leave();
  return ret;
#else /* LWIP_TCPIP_CORE_LOCKING_INPUT */
  struct tcpip_msg *msg;
 
  LWIP_ASSERT("Invalid mbox", sys_mbox_valid_val(mbox));
 
  msg = (struct tcpip_msg *)memp_malloc(MEMP_TCPIP_MSG_INPKT);
  if (msg == NULL) {
    tcpip_producer_leave();
    return ERR_MEM;
  }
 
  msg->type = TCPIP_MSG_INPKT;
  msg->msg.inp.p = p;
  msg->msg.inp.netif = inp;
  msg->msg.inp.input_fn = input_fn;
  if (sys_mbox_trypost(&mbox, msg) != ERR_OK) {
    memp_free(MEMP_TCPIP_MSG_INPKT, msg);
    tcpip_producer_leave();
    return ERR_MEM;
  }
  tcpip_producer_leave();
  return ERR_OK;
#endif /* LWIP_TCPIP_CORE_LOCKING_INPUT */
}
 
err_t
tcpip_input(struct pbuf *p, struct netif *inp)
{
#if LWIP_ETHERNET
  if (inp->flags & (NETIF_FLAG_ETHARP | NETIF_FLAG_ETHERNET)) {
    return tcpip_inpkt(p, inp, ethernet_input);
  } else
#endif /* LWIP_ETHERNET */
  return tcpip_inpkt(p, inp, ip_input);
}
 
static err_t
tcpip_callback_with_block_admitted(tcpip_callback_fn function, void *ctx, u8_t block)
{
  struct tcpip_msg *msg;
 
  LWIP_ASSERT("Invalid mbox", sys_mbox_valid_val(mbox));
 
  msg = (struct tcpip_msg *)memp_malloc(MEMP_TCPIP_MSG_API);
  if (msg == NULL) {
    return ERR_MEM;
  }
 
  msg->type = TCPIP_MSG_CALLBACK;
  msg->msg.cb.function = function;
  msg->msg.cb.ctx = ctx;
  if (block) {
    sys_mbox_post(&mbox, msg);
  } else {
    if (sys_mbox_trypost(&mbox, msg) != ERR_OK) {
      memp_free(MEMP_TCPIP_MSG_API, msg);
      return ERR_MEM;
    }
  }
  return ERR_OK;
}
 
err_t
tcpip_callback_with_block(tcpip_callback_fn function, void *ctx, u8_t block)
{
  err_t err;
 
  if (!tcpip_producer_enter()) {
    return ERR_CLSD;
  }
  err = tcpip_callback_with_block_admitted(function, ctx, block);
  tcpip_producer_leave();
  return err;
}
 
struct tcpip_callback_wait_context {
  tcpip_callback_fn function;
  void *ctx;
  sys_sem_t completion;
  u8_t retired;
};
 
static void
tcpip_callback_wait_shim(void *arg)
{
  struct tcpip_callback_wait_context *context =
      (struct tcpip_callback_wait_context *)arg;
  context->function(context->ctx);
  sys_sem_signal(&context->completion);
  /* The caller may release callback text and context after this store. */
  __atomic_store_n(&context->retired, 1, __ATOMIC_RELEASE);
}
 
err_t
tcpip_callback_wait(tcpip_callback_fn function, void *ctx)
{
  struct tcpip_callback_wait_context context;
  err_t err;
 
  if (function == NULL) {
    return ERR_ARG;
  }
  if (!tcpip_producer_enter()) {
    return ERR_CLSD;
  }
  if (sys_thread_is_current(
          __atomic_load_n(&tcpip_thread_handle, __ATOMIC_ACQUIRE))) {
    function(ctx);
    tcpip_producer_leave();
    return ERR_OK;
  }
  context.function = function;
  context.ctx = ctx;
  context.retired = 0;
  err = sys_sem_new(&context.completion, 0);
  if (err != ERR_OK) {
    tcpip_producer_leave();
    return err;
  }
 
  err = tcpip_callback_with_block_admitted(tcpip_callback_wait_shim, &context, 1);
  if (err == ERR_OK) {
    sys_arch_sem_wait(&context.completion, 0);
    while (!__atomic_load_n(&context.retired, __ATOMIC_ACQUIRE)) {
    }
  }
  sys_sem_free(&context.completion);
  tcpip_producer_leave();
  return err;
}
 
#if LWIP_TCPIP_TIMEOUT && LWIP_TIMERS
err_t
tcpip_timeout(u32_t msecs, sys_timeout_handler h, void *arg)
{
  struct tcpip_msg *msg;
 
  if (!tcpip_producer_enter()) {
    return ERR_CLSD;
  }
  LWIP_ASSERT("Invalid mbox", sys_mbox_valid_val(mbox));
 
  msg = (struct tcpip_msg *)memp_malloc(MEMP_TCPIP_MSG_API);
  if (msg == NULL) {
    tcpip_producer_leave();
    return ERR_MEM;
  }
 
  msg->type = TCPIP_MSG_TIMEOUT;
  msg->msg.tmo.msecs = msecs;
  msg->msg.tmo.h = h;
  msg->msg.tmo.arg = arg;
  sys_mbox_post(&mbox, msg);
  tcpip_producer_leave();
  return ERR_OK;
}
 
err_t
tcpip_untimeout(sys_timeout_handler h, void *arg)
{
  struct tcpip_msg *msg;
 
  if (!tcpip_producer_enter()) {
    return ERR_CLSD;
  }
  LWIP_ASSERT("Invalid mbox", sys_mbox_valid_val(mbox));
 
  msg = (struct tcpip_msg *)memp_malloc(MEMP_TCPIP_MSG_API);
  if (msg == NULL) {
    tcpip_producer_leave();
    return ERR_MEM;
  }
 
  msg->type = TCPIP_MSG_UNTIMEOUT;
  msg->msg.tmo.h = h;
  msg->msg.tmo.arg = arg;
  sys_mbox_post(&mbox, msg);
  tcpip_producer_leave();
  return ERR_OK;
}
#endif /* LWIP_TCPIP_TIMEOUT && LWIP_TIMERS */
 
 
err_t
tcpip_send_msg_wait_sem(tcpip_callback_fn fn, void *apimsg, sys_sem_t* sem)
{
  if (!tcpip_producer_enter()) {
    return ERR_CLSD;
  }
#if LWIP_TCPIP_CORE_LOCKING
  LWIP_UNUSED_ARG(sem);
  LOCK_TCPIP_CORE();
  fn(apimsg);
  UNLOCK_TCPIP_CORE();
  tcpip_producer_leave();
  return ERR_OK;
#else /* LWIP_TCPIP_CORE_LOCKING */
  TCPIP_MSG_VAR_DECLARE(msg);
 
  LWIP_ASSERT("semaphore not initialized", sys_sem_valid(sem));
  LWIP_ASSERT("Invalid mbox", sys_mbox_valid_val(mbox));
 
#if LWIP_MPU_COMPATIBLE
  msg = (struct tcpip_msg *)memp_malloc(MEMP_TCPIP_MSG_API);
  if (msg == NULL) {
    tcpip_producer_leave();
    return ERR_MEM;
  }
#endif /* LWIP_MPU_COMPATIBLE */
  TCPIP_MSG_VAR_REF(msg).type = TCPIP_MSG_API;
  TCPIP_MSG_VAR_REF(msg).msg.api_msg.function = fn;
  TCPIP_MSG_VAR_REF(msg).msg.api_msg.msg = apimsg;
  sys_mbox_post(&mbox, &TCPIP_MSG_VAR_REF(msg));
  sys_arch_sem_wait(sem, 0);
  TCPIP_MSG_VAR_FREE(msg);
  tcpip_producer_leave();
  return ERR_OK;
#endif /* LWIP_TCPIP_CORE_LOCKING */
}
 
err_t
tcpip_api_call(tcpip_api_call_fn fn, struct tcpip_api_call_data *call)
{
  if (!tcpip_producer_enter()) {
    return ERR_CLSD;
  }
#if LWIP_TCPIP_CORE_LOCKING
  err_t err;
  LOCK_TCPIP_CORE();
  err = fn(call);
  UNLOCK_TCPIP_CORE();
  tcpip_producer_leave();
  return err;
#else /* LWIP_TCPIP_CORE_LOCKING */
  TCPIP_MSG_VAR_DECLARE(msg);
 
#if !LWIP_NETCONN_SEM_PER_THREAD
  err_t err = sys_sem_new(&call->sem, 0);
  if (err != ERR_OK) {
    tcpip_producer_leave();
    return err;
  }
#endif /* LWIP_NETCONN_SEM_PER_THREAD */
 
  LWIP_ASSERT("Invalid mbox", sys_mbox_valid_val(mbox));
 
#if LWIP_MPU_COMPATIBLE
  msg = (struct tcpip_msg *)memp_malloc(MEMP_TCPIP_MSG_API);
  if (msg == NULL) {
#if !LWIP_NETCONN_SEM_PER_THREAD
    sys_sem_free(&call->sem);
#endif /* !LWIP_NETCONN_SEM_PER_THREAD */
    tcpip_producer_leave();
    return ERR_MEM;
  }
#endif /* LWIP_MPU_COMPATIBLE */
  TCPIP_MSG_VAR_REF(msg).type = TCPIP_MSG_API_CALL;
  TCPIP_MSG_VAR_REF(msg).msg.api_call.arg = call;
  TCPIP_MSG_VAR_REF(msg).msg.api_call.function = fn;
#if LWIP_NETCONN_SEM_PER_THREAD
  TCPIP_MSG_VAR_REF(msg).msg.api_call.sem = LWIP_NETCONN_THREAD_SEM_GET();
#else /* LWIP_NETCONN_SEM_PER_THREAD */
  TCPIP_MSG_VAR_REF(msg).msg.api_call.sem = &call->sem;
#endif /* LWIP_NETCONN_SEM_PER_THREAD */
  sys_mbox_post(&mbox, &TCPIP_MSG_VAR_REF(msg));
  sys_arch_sem_wait(TCPIP_MSG_VAR_REF(msg).msg.api_call.sem, 0);
  TCPIP_MSG_VAR_FREE(msg);
 
#if !LWIP_NETCONN_SEM_PER_THREAD
  sys_sem_free(&call->sem);
#endif /* LWIP_NETCONN_SEM_PER_THREAD */
 
  tcpip_producer_leave();
  return call->err;
#endif /* LWIP_TCPIP_CORE_LOCKING */
}
 
struct tcpip_callback_msg*
tcpip_callbackmsg_new(tcpip_callback_fn function, void *ctx)
{
  struct tcpip_msg *msg = (struct tcpip_msg *)memp_malloc(MEMP_TCPIP_MSG_API);
  if (msg == NULL) {
    return NULL;
  }
  msg->type = TCPIP_MSG_CALLBACK_STATIC;
  msg->msg.cb.function = function;
  msg->msg.cb.ctx = ctx;
  return (struct tcpip_callback_msg*)msg;
}
 
void
tcpip_callbackmsg_delete(struct tcpip_callback_msg* msg)
{
  memp_free(MEMP_TCPIP_MSG_API, msg);
}
 
err_t
tcpip_trycallback(struct tcpip_callback_msg* msg)
{
  err_t err;
 
  if (!tcpip_producer_enter()) {
    return ERR_CLSD;
  }
  LWIP_ASSERT("Invalid mbox", sys_mbox_valid_val(mbox));
  err = sys_mbox_trypost(&mbox, msg);
  tcpip_producer_leave();
  return err;
}
 
void
tcpip_init(tcpip_init_done_fn initfunc, void *arg)
{
  u8_t state = TCPIP_STATE_STOPPED;
  if (!__atomic_compare_exchange_n(
          &tcpip_shutdown_state, &state, TCPIP_STATE_INITIALIZING, 0,
          __ATOMIC_ACQ_REL, __ATOMIC_ACQUIRE)) {
    LWIP_ASSERT("tcpip_init called outside stopped state", 0);
    return;
  }
  LWIP_ASSERT("tcpip_init with active producers",
              __atomic_load_n(&tcpip_active_producers, __ATOMIC_ACQUIRE) == 0);
  lwip_init();
 
  tcpip_init_done = initfunc;
  tcpip_init_done_arg = arg;
  if (sys_mbox_new(&mbox, TCPIP_MBOX_SIZE) != ERR_OK) {
    LWIP_ASSERT("failed to create tcpip_thread mbox", 0);
  }
#if LWIP_TCPIP_CORE_LOCKING
  if (sys_mutex_new(&lock_tcpip_core) != ERR_OK) {
    LWIP_ASSERT("failed to create lock_tcpip_core", 0);
  }
#endif /* LWIP_TCPIP_CORE_LOCKING */
 
  sys_thread_t thread = sys_thread_new(TCPIP_THREAD_NAME, tcpip_thread, NULL,
                                       TCPIP_THREAD_STACKSIZE, TCPIP_THREAD_PRIO);
  LWIP_ASSERT("failed to create tcpip_thread", thread != NULL);
  __atomic_store_n(&tcpip_thread_handle, thread, __ATOMIC_RELEASE);
  __atomic_store_n(&tcpip_shutdown_state, TCPIP_STATE_RUNNING, __ATOMIC_RELEASE);
}
 
err_t
tcpip_shutdown(void)
{
  u8_t state = __atomic_load_n(&tcpip_shutdown_state, __ATOMIC_ACQUIRE);
 
  if (state == TCPIP_STATE_STOPPED) {
    return ERR_OK;
  }
  if (state == TCPIP_STATE_FAILED) {
    return ERR_IF;
  }
  if (state == TCPIP_STATE_STOPPING || state == TCPIP_STATE_INITIALIZING) {
    return ERR_INPROGRESS;
  }
 
  if (!tcpip_producer_enter()) {
    state = __atomic_load_n(&tcpip_shutdown_state, __ATOMIC_ACQUIRE);
    return state == TCPIP_STATE_STOPPED
               ? ERR_OK
               : (state == TCPIP_STATE_FAILED ? ERR_IF : ERR_INPROGRESS);
  }
 
  sys_thread_t thread =
      __atomic_load_n(&tcpip_thread_handle, __ATOMIC_ACQUIRE);
  const int current = sys_thread_is_current(thread);
  tcpip_producer_leave();
  if (current) {
    return ERR_USE;
  }
 
  state = __atomic_load_n(&tcpip_shutdown_state, __ATOMIC_ACQUIRE);
  if (state != TCPIP_STATE_RUNNING) {
    return state == TCPIP_STATE_STOPPED
               ? ERR_OK
               : (state == TCPIP_STATE_FAILED ? ERR_IF : ERR_INPROGRESS);
  }
 
  state = TCPIP_STATE_RUNNING;
  if (!__atomic_compare_exchange_n(
          &tcpip_shutdown_state, &state, TCPIP_STATE_STOPPING, 0,
          __ATOMIC_ACQ_REL, __ATOMIC_ACQUIRE)) {
    return state == TCPIP_STATE_STOPPED
               ? ERR_OK
               : (state == TCPIP_STATE_FAILED ? ERR_IF : ERR_INPROGRESS);
  }
 
  while (__atomic_load_n(&tcpip_active_producers, __ATOMIC_ACQUIRE) != 0) {
    sys_msleep(1);
  }
 
  tcpip_shutdown_msg.type = TCPIP_MSG_SHUTDOWN;
  if (sys_mbox_post_and_close(&mbox, &tcpip_shutdown_msg) != ERR_OK) {
    __atomic_store_n(&tcpip_shutdown_state, TCPIP_STATE_FAILED, __ATOMIC_RELEASE);
    return ERR_CLSD;
  }
  thread = __atomic_load_n(&tcpip_thread_handle, __ATOMIC_ACQUIRE);
  if (!sys_thread_join(thread)) {
    __atomic_store_n(&tcpip_shutdown_state, TCPIP_STATE_FAILED, __ATOMIC_RELEASE);
    return ERR_IF;
  }
  __atomic_store_n(&tcpip_thread_handle, NULL, __ATOMIC_RELEASE);
 
#if LWIP_TCPIP_CORE_LOCKING
  if (sys_mutex_valid(&lock_tcpip_core)) {
    sys_mutex_free(&lock_tcpip_core);
    sys_mutex_set_invalid(&lock_tcpip_core);
  }
#endif /* LWIP_TCPIP_CORE_LOCKING */
  if (sys_mbox_valid_val(mbox)) {
    sys_mbox_free(&mbox);
    sys_mbox_set_invalid_val(mbox);
  }
  tcpip_init_done = NULL;
  tcpip_init_done_arg = NULL;
  __atomic_store_n(&tcpip_shutdown_state, TCPIP_STATE_STOPPED, __ATOMIC_RELEASE);
  return ERR_OK;
}
 
static void
pbuf_free_int(void *p)
{
  struct pbuf *q = (struct pbuf *)p;
  pbuf_free(q);
}
 
err_t
pbuf_free_callback(struct pbuf *p)
{
  return tcpip_callback_with_block(pbuf_free_int, p, 0);
}
 
err_t
mem_free_callback(void *m)
{
  return tcpip_callback_with_block(mem_free, m, 0);
}
 
#endif /* !NO_SYS */