LWIP 在netconn_free函数内报错

发布于 2021-01-08 13:26:07 浏览：2188 订阅该版

STM32F107VCT6使用LWIP2.02协议栈，不建立网络连接的情况下，使用阻塞式tcp发送和接收，过程中多次开启并关闭socket连接，反复上万次后，出现报错。
因为不熟悉lwip协议栈内部工作原理，所以想请教如何避免发生这样的错误。

报错日志如下：
```
PCB must be deallocated outside this function
Assertion: 730 in ../rt-thread/components/net/lwip-2.0.2/src/api/api_msg.c, thread to_iotse
recvmbox must be deallocated before calling this function
Assertion: 732 in ../rt-thread/components/net/lwip-2.0.2/src/api/api_msg.c, thread to_iotse
acceptmbox must be deallocated before calling this function
Assertion: 735 in ../rt-thread/components/net/lwip-2.0.2/src/api/api_msg.c, thread to_iotse
psr: 0x81000000
r00: 0xfa77b30c
r01: 0x0000000a
r02: 0x80000000
r03: 0x200024f0
r04: 0xfa77b30c
r05: 0xffffffff
r06: 0x20002234
r07: 0x00000008
r08: 0x2000221c
r09: 0x0000221e
r10: 0x20002818
r11: 0xdeadbeef
r12: 0x0800fb63
 lr: 0x08004123
 pc: 0x08004058
hard fault on thread: to_iotse
```

出现问题的函数如下：
```
/**
 * Delete a netconn and all its resources.
 * The pcb is NOT freed (since we might not be in the right thread context do this).
 *
 * @param conn the netconn to free
 */
void
netconn_free(struct netconn *conn)
{
  LWIP_ASSERT("PCB must be deallocated outside this function", conn->pcb.tcp == NULL);
  LWIP_ASSERT("recvmbox must be deallocated before calling this function",
    !sys_mbox_valid(&conn->recvmbox));
#if LWIP_TCP
  LWIP_ASSERT("acceptmbox must be deallocated before calling this function",
    !sys_mbox_valid(&conn->acceptmbox));
#endif /* LWIP_TCP */

#if !LWIP_NETCONN_SEM_PER_THREAD
  sys_sem_free(&conn->op_completed);
  sys_sem_set_invalid(&conn->op_completed);
#endif

memp_free(MEMP_NETCONN, conn);
}
```