tcp.c

linux2.6.16版本

	}

	o2net_init_msg(msg, caller_bytes, msg_type, key);

	vec[0].iov_len = sizeof(struct o2net_msg);
	vec[0].iov_base = msg;
	memcpy(&vec[1], caller_vec, caller_veclen * sizeof(struct kvec));

	ret = o2net_prep_nsw(nn, &nsw);
	if (ret)
		goto out;

	msg->msg_num = cpu_to_be32(nsw.ns_id);

	/* finally, convert the message header to network byte-order
	 * and send */
	ret = o2net_send_tcp_msg(sc->sc_sock, vec, veclen,
				 sizeof(struct o2net_msg) + caller_bytes);
	msglog(msg, "sending returned %d\n", ret);
	if (ret < 0) {
		mlog(0, "error returned from o2net_send_tcp_msg=%d\n", ret);
		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;

	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);
	do_gettimeofday(&sc->sc_tv_func_stop);

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

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;
	}

	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_postpone_idle(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);

	/* 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;

			/* this working relies on the handshake being
			 * smaller than the normal message header */
			if (sc->sc_page_off >= sizeof(struct o2net_handshake)&&
			    !sc->sc_handshake_ok && o2net_check_handshake(sc)) {
				ret = -EPROTO;
				goto out;
			}

			/* 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(void *arg)
{
	struct o2net_sock_container *sc = arg;
	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;
}

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

/* 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(void *arg)
{
	struct o2net_sock_container *sc = arg;

	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_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(void *arg)
{
	struct o2net_sock_container *sc = arg;

	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);

	mlog(ML_NOTICE, "connection to " SC_NODEF_FMT " has been idle for 10 "
	     "seconds, shutting it down.\n", SC_NODEF_ARGS(sc));
	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_postpone_idle(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,
				    O2NET_KEEPALIVE_DELAY_SECS * HZ);
	do_gettimeofday(&sc->sc_tv_timer);
	mod_timer(&sc->sc_idle_timeout,
		  jiffies + (O2NET_IDLE_TIMEOUT_SECS * HZ));
}

/* 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(void *arg)
{
	struct o2net_node *nn = arg;
	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;

	/* 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 */
	if (nn->nn_sc || nn->nn_persistent_error)
		arg = NULL;
	spin_unlock(&nn->nn_lock);
	if (arg == NULL) /* *shrug*, needed some indicator */
		goto out;

	nn->nn_last_connect_attempt = jiffies;

	sc = sc_alloc(node);
	if (sc == NULL) {
		mlog(0, "couldn't allocate sc\n");
		ret = -ENOMEM;
		goto out;
	}

	ret = sock_create(PF_INET, SOCK_STREAM, IPPROTO_TCP, &sock);
	if (ret < 0) {
		mlog(0, "can't create socket: %d\n", ret);
		goto out;
	}
	sc->sc_sock = sock; /* freed by sc_kref_release */

	sock->sk->sk_allocation = GFP_ATOMIC;

	myaddr.sin_family = AF_INET;
	myaddr.sin_addr.s_addr = (__force u32)mynode->nd_ipv4_address;
	myaddr.sin_port = (__force u16)htons(0); /* any port */

	ret = sock->ops->bind(sock, (struct sockaddr *)&myaddr,
			      sizeof(myaddr));
	if (ret) {
		mlog(ML_ERROR, "bind failed with %d at address %u.%u.%u.%u\n",
		     ret, NIPQUAD(mynode->nd_ipv4_address));
		goto out;
	}

	ret = o2net_set_nodelay(sc->sc_sock);
	if (ret) {
		mlog(ML_ERROR, "setting TCP_NODELAY failed with %d\n", ret);