freertos_lwip stm32F2系列非线程安全需要加锁保护

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我在工作中需要在STM32F2系列下，用freertos和LWIP开发一个服务器端的TCP/IP服务。

由于内存有限并且freertos不便于利用fork函数新建线程，因此采用了select模式编写代码。

开始通讯没有问题但是在多次连接或者长时间通讯时，会出现用于TCP/IP通讯的任务被挂起，导致无法再次接受数据，代码如下：

void NetZeroEntryFun(void const * argument)
{
int ts_sock_m = -1;
int ts_sock_s = -1;
int iSelectRet = -1;
struct sockaddr_in sin;
int sin_len = 0;
int i = 0;
int maxi = 0;
int maxfd;
fd_set rset;
fd_set allset;
int n_received = -1;
NET_MSG stNetMsg;
unsigned short usLen = 0;
static struct timeval timeout = {30, 0};
uint16_t nMode = 1;

//ether_init
Net_Initialize();

// allocate a socket
ts_sock_m = socket(AF_INET, SOCK_STREAM, 0);
if (ts_sock_m < 0)
{
return; // Couldn’t Allocate a TCP Socket
}
// Bind the socket to the local port number and IP address
memset(&sin, 0, sizeof(sin));
sin.sin_family = AF_INET;
sin.sin_port = htons(net_astIp[0].port_no);

memcpy((int8_t *)&sin.sin_addr, (int8_t *)net_astIp[0].ip_server_address, 4);

// port number in network byte order
if (bind(ts_sock_m, (const struct sockaddr *)&sin, sizeof(sin)) < 0)
{
closesocket(ts_sock_m);
return; // Bind Failed
}

if (listen(ts_sock_m, NET_MAX_LINK) != 0) // 2 slave ports
{
closesocket(ts_sock_m);
return; // Listen Failed
}

//设置非阻塞模式
ioctlsocket(ts_sock_m,FIONBIO,&nMode);

FD_ZERO(&rset);
FD_ZERO(&allset);
FD_SET(ts_sock_m, &rset);
maxfd = ts_sock_m;

while (1)
{
FD_ZERO(&rset);
FD_SET(ts_sock_m, &rset);

for (i = 0; i < NET_MAX_LINK; i++)
{
if (net_astRecv0[i].ts_sock_s != -1)
{
FD_SET(net_astRecv0[i].ts_sock_s, &rset);
}
}

iSelectRet = select(maxfd + 1, &rset, NULL, NULL, &timeout);

if(iSelectRet < 0)
{/*错误*/
continue;
}
else if(iSelectRet == 0)
{/*超时*/
for (i = 0; i <= maxi; i++)
{
ts_sock_s = net_astRecv0[i].ts_sock_s;
if(ts_sock_s >= 0)
{/*文件描述符不大于0*/
closesocket(ts_sock_s);
FD_CLR(net_astRecv0[i].ts_sock_s, &rset);
net_astRecv0[i].ts_sock_s = -1;
net_astRecv0[i].ulTaskId = 0;
}
}
maxi = 0;
continue;
}
else
{
for (i = 0; i <= maxi; i++)
{
ts_sock_s = net_astRecv0[i].ts_sock_s;

if ((FD_ISSET(ts_sock_s, &rset)) && (ts_sock_s != -1))
{/*有链接则接收数据*/
n_received = recv(ts_sock_s, (int8_t *)stNetMsg.aucData, sizeof(stNetMsg.aucData), MSG_DONTWAIT);

if (n_received <= 0)
{
closesocket(ts_sock_s);
FD_CLR(net_astRecv0[i].ts_sock_s, &rset);
net_astRecv0[i].ts_sock_s = -1;
net_astRecv0[i].ulTaskId = 0;

}
else
{
stNetMsg.usLength = n_received;
stNetMsg.ulTaskId = net_astRecv0[i].ulTaskId;
stNetMsg.ucRtNum = i;
stNetMsg.ucLtNum = NET_LISTEN_TASK0;

if ((stNetMsg.usLength > 7) &&
(stNetMsg.aucData[2] == 0x00) &&
(stNetMsg.aucData[3] == 0x00))
{
memcpy(&usLen, stNetMsg.aucData + 4, 2);
if (usLen == (unsigned short)(stNetMsg.usLength - 6))
{
xQueueSend(xCtrlQueueHandle, &stNetMsg, 0);
}
}
}
}
}

if (FD_ISSET(ts_sock_m, &rset))
{/*创建新的链接*/
sin_len = sizeof(struct sockaddr_in);
ts_sock_s = accept(ts_sock_m, (struct sockaddr *)&sin, (socklen_t *)&sin_len);
if (ts_sock_s == -1)
{
continue;
}

/*设置非阻塞模式*/
nMode = 1;
ioctlsocket(ts_sock_s,FIONBIO,&nMode);
for (i = 0; i < NET_MAX_LINK; i++)
{
if (net_astRecv0[i].ts_sock_s < 0)
{
net_astRecv0[i].ts_sock_s= ts_sock_s;
if (i > maxi)
maxi = i;
break;
}
}
if (ts_sock_s > maxfd)
maxfd = ts_sock_s;
}
}
osDelay(1);
}
}

开始担心自己select用法不对，因此特意做了一个最简单的没有select的TCP/IP通讯的服务端，但是还是与之前的效果一致。

开始对这个bug非常的困惑，也搜了不少关于LWIP和SELECT的用法都没有什么发现，后来一个同事（我的前辈哦）帮我搜索了一下，发现freertos_lwip是非线程安全的，也就是说我在调用recv和send的时候LWIP并没有做保护，而我调用的recv和send的还不在一个任务中，导致了recv和send相互堵塞的情况。

为了解决上述问题，在recv和send调用的时候添加了一个锁。在应用层保证了lwip的线程安全性，修改代码如下：红色部分。。。是修改的内容哦。。。。

修改后的接受部分：

while (1)
{
FD_ZERO(&rset);
FD_SET(ts_sock_m, &rset);

for (i = 0; i < NET_MAX_LINK; i++)
{
if (net_astRecv0[i].ts_sock_s != -1)
{
FD_SET(net_astRecv0[i].ts_sock_s, &rset);
}
}

iSelectRet = select(maxfd + 1, &rset, NULL, NULL, &timeout);

if(iSelectRet < 0)
{/*错误*/
continue;
}
else if(iSelectRet == 0)
{/*超时*/
for (i = 0; i <= maxi; i++)
{
ts_sock_s = net_astRecv0[i].ts_sock_s;
if(ts_sock_s >= 0)
{/*文件描述符不大于0*/
closesocket(ts_sock_s);
FD_CLR(net_astRecv0[i].ts_sock_s, &rset);
net_astRecv0[i].ts_sock_s = -1;
net_astRecv0[i].ulTaskId = 0;
}
}
maxi = 0;
continue;
}
else
{
for (i = 0; i <= maxi; i++)
{
ts_sock_s = net_astRecv0[i].ts_sock_s;

if ((FD_ISSET(ts_sock_s, &rset)) && (ts_sock_s != -1))
{/*有链接则接收数据*/
if(osOK == osSemaphoreWait(NET_SEMPHORE_ZEROHandle, MAX_DELAY))
{
n_received = recv(ts_sock_s, (int8_t *)stNetMsg.aucData, sizeof(stNetMsg.aucData), MSG_DONTWAIT);
osSemaphoreRelease(NET_SEMPHORE_ZEROHandle);

if (n_received <= 0)
{
closesocket(ts_sock_s);
FD_CLR(net_astRecv0[i].ts_sock_s, &rset);
net_astRecv0[i].ts_sock_s = -1;
net_astRecv0[i].ulTaskId = 0;

}
else
{
stNetMsg.usLength = n_received;
stNetMsg.ulTaskId = net_astRecv0[i].ulTaskId;
stNetMsg.ucRtNum = i;
stNetMsg.ucLtNum = NET_LISTEN_TASK0;

if ((stNetMsg.usLength > 7) &&
(stNetMsg.aucData[2] == 0x00) &&
(stNetMsg.aucData[3] == 0x00))
{
memcpy(&usLen, stNetMsg.aucData + 4, 2);
if (usLen == (unsigned short)(stNetMsg.usLength - 6))
{
xQueueSend(xCtrlQueueHandle, &stNetMsg, 0);
}
}
}
}
}
}

if (FD_ISSET(ts_sock_m, &rset))
{/*创建新的链接*/
sin_len = sizeof(struct sockaddr_in);
ts_sock_s = accept(ts_sock_m, (struct sockaddr *)&sin, (socklen_t *)&sin_len);
if (ts_sock_s == -1)
{
continue;
}

/*设置非阻塞模式*/
nMode = 1;
ioctlsocket(ts_sock_s,FIONBIO,&nMode);
for (i = 0; i < NET_MAX_LINK; i++)
{
if (net_astRecv0[i].ts_sock_s < 0)
{
net_astRecv0[i].ts_sock_s= ts_sock_s;
if (i > maxi)
maxi = i;
break;
}
}
if (ts_sock_s > maxfd)
maxfd = ts_sock_s;
}
}
osDelay(1);
}
}

修改后的发送部分：

void Net_send_to_PC(NET_MSG* pstNetMsg)
{
NET_RECV_S stRecvS;

if (pstNetMsg == NULL)
{
return;
}

switch (pstNetMsg->ucLtNum)
{
case NET_LISTEN_TASK0:
if (!_Net_Get_Recv_0(&stRecvS, pstNetMsg->ucRtNum) ||
(pstNetMsg->ulTaskId != stRecvS.ulTaskId) ||
(stRecvS.ts_sock_s < 0))
{
return;
}
break;
default:
return;
}

if(osOK == osSemaphoreWait(NET_SEMPHORE_ZEROHandle, MAX_DELAY))
{
send(stRecvS.ts_sock_s, (int8_t *)pstNetMsg->aucData, pstNetMsg->usLength, 0);
osSemaphoreRelease(NET_SEMPHORE_ZEROHandle);
}

}

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freertos_lwip stm32F2系列 非线程安全需要加锁保护

freertos_lwip stm32F2系列非线程安全需要加锁保护