tcp.c

linux 内核源代码

		goto out;
	}

	/* wait on other node's handler */
	wait_event(nsw.ns_wq, o2net_nsw_completed(nn, &nsw));

	/* Note that we avoid overwriting the callers status return
	 * variable if a system error was reported on the other
	 * side. Callers beware. */
	ret = o2net_sys_err_to_errno(nsw.ns_sys_status);
	if (status && !ret)
		*status = nsw.ns_status;

	mlog(0, "woken, returning system status %d, user status %d\n",
	     ret, nsw.ns_status);
out:
	if (sc)
		sc_put(sc);
	if (vec)
		kfree(vec);
	if (msg)
		kfree(msg);
	o2net_complete_nsw(nn, &nsw, 0, 0, 0);
	return ret;
}
EXPORT_SYMBOL_GPL(o2net_send_message_vec);

int o2net_send_message(u32 msg_type, u32 key, void *data, u32 len,
		       u8 target_node, int *status)
{
	struct kvec vec = {
		.iov_base = data,
		.iov_len = len,
	};
	return o2net_send_message_vec(msg_type, key, &vec, 1,
				      target_node, status);
}
EXPORT_SYMBOL_GPL(o2net_send_message);

static int o2net_send_status_magic(struct socket *sock, struct o2net_msg *hdr,
				   enum o2net_system_error syserr, int err)
{
	struct kvec vec = {
		.iov_base = hdr,
		.iov_len = sizeof(struct o2net_msg),
	};

	BUG_ON(syserr >= O2NET_ERR_MAX);

	/* leave other fields intact from the incoming message, msg_num
	 * in particular */
	hdr->sys_status = cpu_to_be32(syserr);
	hdr->status = cpu_to_be32(err);
	hdr->magic = cpu_to_be16(O2NET_MSG_STATUS_MAGIC);  // twiddle the magic
	hdr->data_len = 0;

	msglog(hdr, "about to send status magic %d\n", err);
	/* hdr has been in host byteorder this whole time */
	return o2net_send_tcp_msg(sock, &vec, 1, sizeof(struct o2net_msg));
}

/* this returns -errno if the header was unknown or too large, etc.
 * after this is called the buffer us reused for the next message */
static int o2net_process_message(struct o2net_sock_container *sc,
				 struct o2net_msg *hdr)
{
	struct o2net_node *nn = o2net_nn_from_num(sc->sc_node->nd_num);
	int ret = 0, handler_status;
	enum  o2net_system_error syserr;
	struct o2net_msg_handler *nmh = NULL;
	void *ret_data = NULL;

	msglog(hdr, "processing message\n");

	o2net_sc_postpone_idle(sc);

	switch(be16_to_cpu(hdr->magic)) {
		case O2NET_MSG_STATUS_MAGIC:
			/* special type for returning message status */
			o2net_complete_nsw(nn, NULL,
					   be32_to_cpu(hdr->msg_num),
					   be32_to_cpu(hdr->sys_status),
					   be32_to_cpu(hdr->status));
			goto out;
		case O2NET_MSG_KEEP_REQ_MAGIC:
			o2net_sendpage(sc, o2net_keep_resp,
				       sizeof(*o2net_keep_resp));
			goto out;
		case O2NET_MSG_KEEP_RESP_MAGIC:
			goto out;
		case O2NET_MSG_MAGIC:
			break;
		default:
			msglog(hdr, "bad magic\n");
			ret = -EINVAL;
			goto out;
			break;
	}

	/* find a handler for it */
	handler_status = 0;
	nmh = o2net_handler_get(be16_to_cpu(hdr->msg_type),
				be32_to_cpu(hdr->key));
	if (!nmh) {
		mlog(ML_TCP, "couldn't find handler for type %u key %08x\n",
		     be16_to_cpu(hdr->msg_type), be32_to_cpu(hdr->key));
		syserr = O2NET_ERR_NO_HNDLR;
		goto out_respond;
	}

	syserr = O2NET_ERR_NONE;

	if (be16_to_cpu(hdr->data_len) > nmh->nh_max_len)
		syserr = O2NET_ERR_OVERFLOW;

	if (syserr != O2NET_ERR_NONE)
		goto out_respond;

	do_gettimeofday(&sc->sc_tv_func_start);
	sc->sc_msg_key = be32_to_cpu(hdr->key);
	sc->sc_msg_type = be16_to_cpu(hdr->msg_type);
	handler_status = (nmh->nh_func)(hdr, sizeof(struct o2net_msg) +
					     be16_to_cpu(hdr->data_len),
					nmh->nh_func_data, &ret_data);
	do_gettimeofday(&sc->sc_tv_func_stop);

out_respond:
	/* this destroys the hdr, so don't use it after this */
	mutex_lock(&sc->sc_send_lock);
	ret = o2net_send_status_magic(sc->sc_sock, hdr, syserr,
				      handler_status);
	mutex_unlock(&sc->sc_send_lock);
	hdr = NULL;
	mlog(0, "sending handler status %d, syserr %d returned %d\n",
	     handler_status, syserr, ret);

	if (nmh) {
		BUG_ON(ret_data != NULL && nmh->nh_post_func == NULL);
		if (nmh->nh_post_func)
			(nmh->nh_post_func)(handler_status, nmh->nh_func_data,
					    ret_data);
	}

out:
	if (nmh)
		o2net_handler_put(nmh);
	return ret;
}

static int o2net_check_handshake(struct o2net_sock_container *sc)
{
	struct o2net_handshake *hand = page_address(sc->sc_page);
	struct o2net_node *nn = o2net_nn_from_num(sc->sc_node->nd_num);

	if (hand->protocol_version != cpu_to_be64(O2NET_PROTOCOL_VERSION)) {
		mlog(ML_NOTICE, SC_NODEF_FMT " advertised net protocol "
		     "version %llu but %llu is required, disconnecting\n",
		     SC_NODEF_ARGS(sc),
		     (unsigned long long)be64_to_cpu(hand->protocol_version),
		     O2NET_PROTOCOL_VERSION);

		/* don't bother reconnecting if its the wrong version. */
		o2net_ensure_shutdown(nn, sc, -ENOTCONN);
		return -1;
	}

	/*
	 * Ensure timeouts are consistent with other nodes, otherwise
	 * we can end up with one node thinking that the other must be down,
	 * but isn't. This can ultimately cause corruption.
	 */
	if (be32_to_cpu(hand->o2net_idle_timeout_ms) !=
				o2net_idle_timeout(sc->sc_node)) {
		mlog(ML_NOTICE, SC_NODEF_FMT " uses a network idle timeout of "
		     "%u ms, but we use %u ms locally.  disconnecting\n",
		     SC_NODEF_ARGS(sc),
		     be32_to_cpu(hand->o2net_idle_timeout_ms),
		     o2net_idle_timeout(sc->sc_node));
		o2net_ensure_shutdown(nn, sc, -ENOTCONN);
		return -1;
	}

	if (be32_to_cpu(hand->o2net_keepalive_delay_ms) !=
			o2net_keepalive_delay(sc->sc_node)) {
		mlog(ML_NOTICE, SC_NODEF_FMT " uses a keepalive delay of "
		     "%u ms, but we use %u ms locally.  disconnecting\n",
		     SC_NODEF_ARGS(sc),
		     be32_to_cpu(hand->o2net_keepalive_delay_ms),
		     o2net_keepalive_delay(sc->sc_node));
		o2net_ensure_shutdown(nn, sc, -ENOTCONN);
		return -1;
	}

	if (be32_to_cpu(hand->o2hb_heartbeat_timeout_ms) !=
			O2HB_MAX_WRITE_TIMEOUT_MS) {
		mlog(ML_NOTICE, SC_NODEF_FMT " uses a heartbeat timeout of "
		     "%u ms, but we use %u ms locally.  disconnecting\n",
		     SC_NODEF_ARGS(sc),
		     be32_to_cpu(hand->o2hb_heartbeat_timeout_ms),
		     O2HB_MAX_WRITE_TIMEOUT_MS);
		o2net_ensure_shutdown(nn, sc, -ENOTCONN);
		return -1;
	}

	sc->sc_handshake_ok = 1;

	spin_lock(&nn->nn_lock);
	/* set valid and queue the idle timers only if it hasn't been
	 * shut down already */
	if (nn->nn_sc == sc) {
		o2net_sc_reset_idle_timer(sc);
		o2net_set_nn_state(nn, sc, 1, 0);
	}
	spin_unlock(&nn->nn_lock);

	/* shift everything up as though it wasn't there */
	sc->sc_page_off -= sizeof(struct o2net_handshake);
	if (sc->sc_page_off)
		memmove(hand, hand + 1, sc->sc_page_off);

	return 0;
}

/* this demuxes the queued rx bytes into header or payload bits and calls
 * handlers as each full message is read off the socket.  it returns -error,
 * == 0 eof, or > 0 for progress made.*/
static int o2net_advance_rx(struct o2net_sock_container *sc)
{
	struct o2net_msg *hdr;
	int ret = 0;
	void *data;
	size_t datalen;

	sclog(sc, "receiving\n");
	do_gettimeofday(&sc->sc_tv_advance_start);

	if (unlikely(sc->sc_handshake_ok == 0)) {
		if(sc->sc_page_off < sizeof(struct o2net_handshake)) {
			data = page_address(sc->sc_page) + sc->sc_page_off;
			datalen = sizeof(struct o2net_handshake) - sc->sc_page_off;
			ret = o2net_recv_tcp_msg(sc->sc_sock, data, datalen);
			if (ret > 0)
				sc->sc_page_off += ret;
		}

		if (sc->sc_page_off == sizeof(struct o2net_handshake)) {
			o2net_check_handshake(sc);
			if (unlikely(sc->sc_handshake_ok == 0))
				ret = -EPROTO;
		}
		goto out;
	}

	/* do we need more header? */
	if (sc->sc_page_off < sizeof(struct o2net_msg)) {
		data = page_address(sc->sc_page) + sc->sc_page_off;
		datalen = sizeof(struct o2net_msg) - sc->sc_page_off;
		ret = o2net_recv_tcp_msg(sc->sc_sock, data, datalen);
		if (ret > 0) {
			sc->sc_page_off += ret;
			/* only swab incoming here.. we can
			 * only get here once as we cross from
			 * being under to over */
			if (sc->sc_page_off == sizeof(struct o2net_msg)) {
				hdr = page_address(sc->sc_page);
				if (be16_to_cpu(hdr->data_len) >
				    O2NET_MAX_PAYLOAD_BYTES)
					ret = -EOVERFLOW;
			}
		}
		if (ret <= 0)
			goto out;
	}

	if (sc->sc_page_off < sizeof(struct o2net_msg)) {
		/* oof, still don't have a header */
		goto out;
	}

	/* this was swabbed above when we first read it */
	hdr = page_address(sc->sc_page);

	msglog(hdr, "at page_off %zu\n", sc->sc_page_off);

	/* do we need more payload? */
	if (sc->sc_page_off - sizeof(struct o2net_msg) < be16_to_cpu(hdr->data_len)) {
		/* need more payload */
		data = page_address(sc->sc_page) + sc->sc_page_off;
		datalen = (sizeof(struct o2net_msg) + be16_to_cpu(hdr->data_len)) -
			  sc->sc_page_off;
		ret = o2net_recv_tcp_msg(sc->sc_sock, data, datalen);
		if (ret > 0)
			sc->sc_page_off += ret;
		if (ret <= 0)
			goto out;
	}

	if (sc->sc_page_off - sizeof(struct o2net_msg) == be16_to_cpu(hdr->data_len)) {
		/* we can only get here once, the first time we read
		 * the payload.. so set ret to progress if the handler
		 * works out. after calling this the message is toast */
		ret = o2net_process_message(sc, hdr);
		if (ret == 0)
			ret = 1;
		sc->sc_page_off = 0;
	}

out:
	sclog(sc, "ret = %d\n", ret);
	do_gettimeofday(&sc->sc_tv_advance_stop);
	return ret;
}

/* this work func is triggerd by data ready.  it reads until it can read no
 * more.  it interprets 0, eof, as fatal.  if data_ready hits while we're doing
 * our work the work struct will be marked and we'll be called again. */
static void o2net_rx_until_empty(struct work_struct *work)
{
	struct o2net_sock_container *sc =
		container_of(work, struct o2net_sock_container, sc_rx_work);
	int ret;

	do {
		ret = o2net_advance_rx(sc);
	} while (ret > 0);

	if (ret <= 0 && ret != -EAGAIN) {
		struct o2net_node *nn = o2net_nn_from_num(sc->sc_node->nd_num);
		sclog(sc, "saw error %d, closing\n", ret);
		/* not permanent so read failed handshake can retry */
		o2net_ensure_shutdown(nn, sc, 0);
	}

	sc_put(sc);
}

static int o2net_set_nodelay(struct socket *sock)
{
	int ret, val = 1;
	mm_segment_t oldfs;

	oldfs = get_fs();
	set_fs(KERNEL_DS);

	/*
	 * Dear unsuspecting programmer,
	 *
	 * Don't use sock_setsockopt() for SOL_TCP.  It doesn't check its level
	 * argument and assumes SOL_SOCKET so, say, your TCP_NODELAY will
	 * silently turn into SO_DEBUG.
	 *
	 * Yours,
	 * Keeper of hilariously fragile interfaces.
	 */
	ret = sock->ops->setsockopt(sock, SOL_TCP, TCP_NODELAY,
				    (char __user *)&val, sizeof(val));

	set_fs(oldfs);
	return ret;
}

static void o2net_initialize_handshake(void)
{
	o2net_hand->o2hb_heartbeat_timeout_ms = cpu_to_be32(
		O2HB_MAX_WRITE_TIMEOUT_MS);
	o2net_hand->o2net_idle_timeout_ms = cpu_to_be32(
		o2net_idle_timeout(NULL));
	o2net_hand->o2net_keepalive_delay_ms = cpu_to_be32(
		o2net_keepalive_delay(NULL));
	o2net_hand->o2net_reconnect_delay_ms = cpu_to_be32(
		o2net_reconnect_delay(NULL));
}

/* ------------------------------------------------------------ */

/* called when a connect completes and after a sock is accepted.  the
 * rx path will see the response and mark the sc valid */
static void o2net_sc_connect_completed(struct work_struct *work)
{
	struct o2net_sock_container *sc =
		container_of(work, struct o2net_sock_container,
			     sc_connect_work);

	mlog(ML_MSG, "sc sending handshake with ver %llu id %llx\n",
              (unsigned long long)O2NET_PROTOCOL_VERSION,
	      (unsigned long long)be64_to_cpu(o2net_hand->connector_id));

	o2net_initialize_handshake();
	o2net_sendpage(sc, o2net_hand, sizeof(*o2net_hand));
	sc_put(sc);
}

/* this is called as a work_struct func. */
static void o2net_sc_send_keep_req(struct work_struct *work)
{
	struct o2net_sock_container *sc =
		container_of(work, struct o2net_sock_container,
			     sc_keepalive_work.work);

	o2net_sendpage(sc, o2net_keep_req, sizeof(*o2net_keep_req));
	sc_put(sc);
}

/* socket shutdown does a del_timer_sync against this as it tears down.
 * we can't start this timer until we've got to the point in sc buildup
 * where shutdown is going to be involved */
static void o2net_idle_timer(unsigned long data)
{
	struct o2net_sock_container *sc = (struct o2net_sock_container *)data;
	struct timeval now;

	do_gettimeofday(&now);

	printk(KERN_INFO "o2net: connection to " SC_NODEF_FMT " has been idle for %u.%u "
	     "seconds, shutting it down.\n", SC_NODEF_ARGS(sc),
		     o2net_idle_timeout(sc->sc_node) / 1000,
		     o2net_idle_timeout(sc->sc_node) % 1000);
	mlog(ML_NOTICE, "here are some times that might help debug the "
	     "situation: (tmr %ld.%ld now %ld.%ld dr %ld.%ld adv "
	     "%ld.%ld:%ld.%ld func (%08x:%u) %ld.%ld:%ld.%ld)\n",
	     sc->sc_tv_timer.tv_sec, (long) sc->sc_tv_timer.tv_usec, 
	     now.tv_sec, (long) now.tv_usec,
	     sc->sc_tv_data_ready.tv_sec, (long) sc->sc_tv_data_ready.tv_usec,
	     sc->sc_tv_advance_start.tv_sec,
	     (long) sc->sc_tv_advance_start.tv_usec,
	     sc->sc_tv_advance_stop.tv_sec,
	     (long) sc->sc_tv_advance_stop.tv_usec,
	     sc->sc_msg_key, sc->sc_msg_type,
	     sc->sc_tv_func_start.tv_sec, (long) sc->sc_tv_func_start.tv_usec,
	     sc->sc_tv_func_stop.tv_sec, (long) sc->sc_tv_func_stop.tv_usec);

	o2net_sc_queue_work(sc, &sc->sc_shutdown_work);
}

static void o2net_sc_reset_idle_timer(struct o2net_sock_container *sc)
{
	o2net_sc_cancel_delayed_work(sc, &sc->sc_keepalive_work);
	o2net_sc_queue_delayed_work(sc, &sc->sc_keepalive_work,
		      msecs_to_jiffies(o2net_keepalive_delay(sc->sc_node)));
	do_gettimeofday(&sc->sc_tv_timer);
	mod_timer(&sc->sc_idle_timeout,
	       jiffies + msecs_to_jiffies(o2net_idle_timeout(sc->sc_node)));
}

static void o2net_sc_postpone_idle(struct o2net_sock_container *sc)
{
	/* Only push out an existing timer */
	if (timer_pending(&sc->sc_idle_timeout))
		o2net_sc_reset_idle_timer(sc);
}

/* this work func is kicked whenever a path sets the nn state which doesn't
 * have valid set.  This includes seeing hb come up, losing a connection,
 * having a connect attempt fail, etc. This centralizes the logic which decides
 * if a connect attempt should be made or if we should give up and all future
 * transmit attempts should fail */
static void o2net_start_connect(struct work_struct *work)
{
	struct o2net_node *nn =
		container_of(work, struct o2net_node, nn_connect_work.work);
	struct o2net_sock_container *sc = NULL;
	struct o2nm_node *node = NULL, *mynode = NULL;
	struct socket *sock = NULL;
	struct sockaddr_in myaddr = {0, }, remoteaddr = {0, };
	int ret = 0, stop;

	/* if we're greater we initiate tx, otherwise we accept */
	if (o2nm_this_node() <= o2net_num_from_nn(nn))
		goto out;

	/* watch for racing with tearing a node down */
	node = o2nm_get_node_by_num(o2net_num_from_nn(nn));
	if (node == NULL) {
		ret = 0;
		goto out;
	}

	mynode = o2nm_get_node_by_num(o2nm_this_node());
	if (mynode == NULL) {
		ret = 0;
		goto out;
	}

	spin_lock(&nn->nn_lock);
	/* see if we already have one pending or have given up */
	stop = (nn->nn_sc || nn->nn_persistent_error);
	spin_unlock(&nn->nn_lock);
	if (stop)
		goto out;

	nn->nn_last_connect_attempt = jiffies;