Function done_socket

components/net/lwip/lwip-2.1.2/src/api/sockets.c:376–401

In full-duplex mode,sock->fd_used != 0 prevents a socket descriptor from being * released (and possibly reused) when used from more than one thread * (e.g. read-while-write or close-while-write, etc) * This function is called at the end of functions using (try)get_socket*(). */

 * This function is called at the end of functions using (try)get_socket*().
 */
static void
done_socket(struct lwip_sock *sock)
{
  int freed = 0;
  int is_tcp = 0;
  struct netconn *conn = NULL;
  union lwip_sock_lastdata lastdata;
  SYS_ARCH_DECL_PROTECT(lev);
  LWIP_ASSERT("sock != NULL", sock != NULL);

  SYS_ARCH_PROTECT(lev);
  LWIP_ASSERT("sock->fd_used > 0", sock->fd_used > 0);
  if (--sock->fd_used == 0) {
    if (sock->fd_free_pending) {
      /* free the socket */
      sock->fd_used = 1;
      is_tcp = sock->fd_free_pending & LWIP_SOCK_FD_FREE_TCP;
      freed = free_socket_locked(sock, is_tcp, &conn, &lastdata);
    }
  }
  SYS_ARCH_UNPROTECT(lev);

  if (freed) {
    free_socket_free_elements(is_tcp, conn, &lastdata);
  }
}

#else /* LWIP_NETCONN_FULLDUPLEX */
#define sock_inc_used(sock)         1