c - Always print EAGAIN when calling accept after epoll_wait -

i'm using epoll monitor listen fd event, after epollin event occur call accept process, eagain error. can give me suggestions? thanks!

[log] print information below time

info jan 01 00:02:08:924 [385] poll_loop: epoll has 1 event

info jan 01 00:02:08:925 [385] poll_loop: event fd 0, event type:1

info jan 01 00:02:08:925 [385] handle_connect: fd 0,

error jan 01 00:02:08:925 [385] handle_connect: accept returned error 11 resource temporarily unavailable ... retrying, listen fd:0.

[code]

    ................          listenfd = listen_sock (port, &addrlen);         socket_nonblocking(listenfd);         g_epollfd = epoll_create(max_events);           register_read(listenfd);      .................          while (!config.quit)         {              int fds = epoll_wait(g_epollfd, g_events, max_events, -1);                if (fds < 0)             {                 log_message(log_crit, "epoll wait error %d %s, continue", errno, strerror(errno));                 continue;             }              log_message(log_info, "epoll has %d event", fds);             (i = 0; < fds; ++i)              {                  log_message(log_info, "event fd %d, event type:%d", g_events[i].data.fd, g_events[i].events);                  if ((g_events[i].events & epollerr)                      || (g_events[i].events & epollhup)                     /*|| (g_events[i].events & pollnval) compile err*/)                 {                     log_message(log_info, "a disconnect occurs, [fd:%d]", g_events[i].data.fd);                     handle_disconnect(g_events[i].data.fd);                           continue;                 }                 if (g_events[i].events & epollin)                 {                      if (listenfd == g_events[i].data.fd)                     {                         handle_connect(listenfd, ptr);                     }                     else if (g_dnsfd == g_events[i].data.fd)                     {                         dns_poll(g_dns);                     }                     else                     {                         handle_input(g_events[i].data.fd);                     }                 }     ...................      void handle_connect(int fd, struct child_s *ptr)     {         int connfd;         struct conn_s *connptr = 0;         char peer_ipaddr[ip_length];          socklen_t clilen = sizeof(struct sockaddr_in);         struct sockaddr_in cliaddr ;          log_message(log_info, "fd %d, ");         connfd = accept (fd, (struct sockaddr*)(&cliaddr), &clilen);          if (connfd < 0)          {             log_message (log_err, "accept returned error %d %s ... retrying, listen fd:%d", errno, strerror (errno), fd);             return;         }      ......................  #define register_epoll_event(_fd, evt, op) \ do\ {\     struct epoll_event epv = {0, {0}};  \     epv.data.fd = _fd;  \     epv.events  = evt;  /*epolllt default*/\ \     if(epoll_ctl(g_epollfd, op, _fd, &epv) < 0)  \     {\         /*if ((errno != eexist) && (errno != enoent))*/\         {\             log_message(log_err, "epool ctl set failed, fd %d, errno %d: %s", _fd, errno, strerror(errno));  \             return ;\         }\     }\     log_message(log_info, "epool ctl set sucess, fd %d", _fd);\ }while(0)   void register_read(int fd, int* evt) {     if (0 == evt)     {         register_epoll_event(fd, epollin, epoll_ctl_add);     }     else if (0 == *evt)     {         *evt |= epollin;          register_epoll_event(fd, (*evt), epoll_ctl_add);     }     else if (!(*evt & epollin))     {         *evt |= epollin;         register_epoll_event(fd, (*evt), epoll_ctl_mod);     }     else     {         log_message("event %d fd %d there", *evt, fd);     }  } 

this line says all:

info jan 01 00:02:08:925 [385] poll_loop: event fd 0, event type:1 

fd 0 stdin, not listening socket. evidently, adding "0" epoll set instead of listening socket.

you didn't show epoll_ctl getting called add listenfd epoll set (g_epollfd). presumably, that's register_read() call above about. expect this:

int result; epoll_event readevent = {};  readevent.data.fd = listenfd; readevent.events = epollin; result = epoll_ctl(g_epollfd, epoll_ctl_add, listenfd, &readevent); 

notice listenfd specified both third parameter epoll_ctl member var on fourth parameter (readevent.data.fd).