tcp.c

linux 内核源代码

{
	void (*state_change)(struct sock *sk);
	struct o2net_sock_container *sc;

	read_lock(&sk->sk_callback_lock);
	sc = sk->sk_user_data;
	if (sc == NULL) {
		state_change = sk->sk_state_change;
		goto out;
	}

	sclog(sc, "state_change to %d\n", sk->sk_state);

	state_change = sc->sc_state_change;

	switch(sk->sk_state) {
		/* ignore connecting sockets as they make progress */
		case TCP_SYN_SENT:
		case TCP_SYN_RECV:
			break;
		case TCP_ESTABLISHED:
			o2net_sc_queue_work(sc, &sc->sc_connect_work);
			break;
		default:
			o2net_sc_queue_work(sc, &sc->sc_shutdown_work);
			break;
	}
out:
	read_unlock(&sk->sk_callback_lock);
	state_change(sk);
}

/*
 * we register callbacks so we can queue work on events before calling
 * the original callbacks.  our callbacks our careful to test user_data
 * to discover when they've reaced with o2net_unregister_callbacks().
 */
static void o2net_register_callbacks(struct sock *sk,
				     struct o2net_sock_container *sc)
{
	write_lock_bh(&sk->sk_callback_lock);

	/* accepted sockets inherit the old listen socket data ready */
	if (sk->sk_data_ready == o2net_listen_data_ready) {
		sk->sk_data_ready = sk->sk_user_data;
		sk->sk_user_data = NULL;
	}

	BUG_ON(sk->sk_user_data != NULL);
	sk->sk_user_data = sc;
	sc_get(sc);

	sc->sc_data_ready = sk->sk_data_ready;
	sc->sc_state_change = sk->sk_state_change;
	sk->sk_data_ready = o2net_data_ready;
	sk->sk_state_change = o2net_state_change;

	mutex_init(&sc->sc_send_lock);

	write_unlock_bh(&sk->sk_callback_lock);
}

static int o2net_unregister_callbacks(struct sock *sk,
			           struct o2net_sock_container *sc)
{
	int ret = 0;

	write_lock_bh(&sk->sk_callback_lock);
	if (sk->sk_user_data == sc) {
		ret = 1;
		sk->sk_user_data = NULL;
		sk->sk_data_ready = sc->sc_data_ready;
		sk->sk_state_change = sc->sc_state_change;
	}
	write_unlock_bh(&sk->sk_callback_lock);

	return ret;
}

/*
 * this is a little helper that is called by callers who have seen a problem
 * with an sc and want to detach it from the nn if someone already hasn't beat
 * them to it.  if an error is given then the shutdown will be persistent
 * and pending transmits will be canceled.
 */
static void o2net_ensure_shutdown(struct o2net_node *nn,
			           struct o2net_sock_container *sc,
				   int err)
{
	spin_lock(&nn->nn_lock);
	if (nn->nn_sc == sc)
		o2net_set_nn_state(nn, NULL, 0, err);
	spin_unlock(&nn->nn_lock);
}

/*
 * This work queue function performs the blocking parts of socket shutdown.  A
 * few paths lead here.  set_nn_state will trigger this callback if it sees an
 * sc detached from the nn.  state_change will also trigger this callback
 * directly when it sees errors.  In that case we need to call set_nn_state
 * ourselves as state_change couldn't get the nn_lock and call set_nn_state
 * itself.
 */
static void o2net_shutdown_sc(struct work_struct *work)
{
	struct o2net_sock_container *sc =
		container_of(work, struct o2net_sock_container,
			     sc_shutdown_work);
	struct o2net_node *nn = o2net_nn_from_num(sc->sc_node->nd_num);

	sclog(sc, "shutting down\n");

	/* drop the callbacks ref and call shutdown only once */
	if (o2net_unregister_callbacks(sc->sc_sock->sk, sc)) {
		/* we shouldn't flush as we're in the thread, the
		 * races with pending sc work structs are harmless */
		del_timer_sync(&sc->sc_idle_timeout);
		o2net_sc_cancel_delayed_work(sc, &sc->sc_keepalive_work);
		sc_put(sc);
		kernel_sock_shutdown(sc->sc_sock, SHUT_RDWR);
	}

	/* not fatal so failed connects before the other guy has our
	 * heartbeat can be retried */
	o2net_ensure_shutdown(nn, sc, 0);
	sc_put(sc);
}

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

static int o2net_handler_cmp(struct o2net_msg_handler *nmh, u32 msg_type,
			     u32 key)
{
	int ret = memcmp(&nmh->nh_key, &key, sizeof(key));

	if (ret == 0)
		ret = memcmp(&nmh->nh_msg_type, &msg_type, sizeof(msg_type));

	return ret;
}

static struct o2net_msg_handler *
o2net_handler_tree_lookup(u32 msg_type, u32 key, struct rb_node ***ret_p,
			  struct rb_node **ret_parent)
{
        struct rb_node **p = &o2net_handler_tree.rb_node;
        struct rb_node *parent = NULL;
	struct o2net_msg_handler *nmh, *ret = NULL;
	int cmp;

        while (*p) {
                parent = *p;
                nmh = rb_entry(parent, struct o2net_msg_handler, nh_node);
		cmp = o2net_handler_cmp(nmh, msg_type, key);

                if (cmp < 0)
                        p = &(*p)->rb_left;
                else if (cmp > 0)
                        p = &(*p)->rb_right;
                else {
			ret = nmh;
                        break;
		}
        }

        if (ret_p != NULL)
                *ret_p = p;
        if (ret_parent != NULL)
                *ret_parent = parent;

        return ret;
}

static void o2net_handler_kref_release(struct kref *kref)
{
	struct o2net_msg_handler *nmh;
	nmh = container_of(kref, struct o2net_msg_handler, nh_kref);

	kfree(nmh);
}

static void o2net_handler_put(struct o2net_msg_handler *nmh)
{
	kref_put(&nmh->nh_kref, o2net_handler_kref_release);
}

/* max_len is protection for the handler func.  incoming messages won't
 * be given to the handler if their payload is longer than the max. */
int o2net_register_handler(u32 msg_type, u32 key, u32 max_len,
			   o2net_msg_handler_func *func, void *data,
			   o2net_post_msg_handler_func *post_func,
			   struct list_head *unreg_list)
{
	struct o2net_msg_handler *nmh = NULL;
	struct rb_node **p, *parent;
	int ret = 0;

	if (max_len > O2NET_MAX_PAYLOAD_BYTES) {
		mlog(0, "max_len for message handler out of range: %u\n",
			max_len);
		ret = -EINVAL;
		goto out;
	}

	if (!msg_type) {
		mlog(0, "no message type provided: %u, %p\n", msg_type, func);
		ret = -EINVAL;
		goto out;

	}
	if (!func) {
		mlog(0, "no message handler provided: %u, %p\n",
		       msg_type, func);
		ret = -EINVAL;
		goto out;
	}

       	nmh = kzalloc(sizeof(struct o2net_msg_handler), GFP_NOFS);
	if (nmh == NULL) {
		ret = -ENOMEM;
		goto out;
	}

	nmh->nh_func = func;
	nmh->nh_func_data = data;
	nmh->nh_post_func = post_func;
	nmh->nh_msg_type = msg_type;
	nmh->nh_max_len = max_len;
	nmh->nh_key = key;
	/* the tree and list get this ref.. they're both removed in
	 * unregister when this ref is dropped */
	kref_init(&nmh->nh_kref);
	INIT_LIST_HEAD(&nmh->nh_unregister_item);

	write_lock(&o2net_handler_lock);
	if (o2net_handler_tree_lookup(msg_type, key, &p, &parent))
		ret = -EEXIST;
	else {
	        rb_link_node(&nmh->nh_node, parent, p);
		rb_insert_color(&nmh->nh_node, &o2net_handler_tree);
		list_add_tail(&nmh->nh_unregister_item, unreg_list);

		mlog(ML_TCP, "registered handler func %p type %u key %08x\n",
		     func, msg_type, key);
		/* we've had some trouble with handlers seemingly vanishing. */
		mlog_bug_on_msg(o2net_handler_tree_lookup(msg_type, key, &p,
							  &parent) == NULL,
			        "couldn't find handler we *just* registerd "
				"for type %u key %08x\n", msg_type, key);
	}
	write_unlock(&o2net_handler_lock);
	if (ret)
		goto out;

out:
	if (ret)
		kfree(nmh);

	return ret;
}
EXPORT_SYMBOL_GPL(o2net_register_handler);

void o2net_unregister_handler_list(struct list_head *list)
{
	struct o2net_msg_handler *nmh, *n;

	write_lock(&o2net_handler_lock);
	list_for_each_entry_safe(nmh, n, list, nh_unregister_item) {
		mlog(ML_TCP, "unregistering handler func %p type %u key %08x\n",
		     nmh->nh_func, nmh->nh_msg_type, nmh->nh_key);
		rb_erase(&nmh->nh_node, &o2net_handler_tree);
		list_del_init(&nmh->nh_unregister_item);
		kref_put(&nmh->nh_kref, o2net_handler_kref_release);
	}
	write_unlock(&o2net_handler_lock);
}
EXPORT_SYMBOL_GPL(o2net_unregister_handler_list);

static struct o2net_msg_handler *o2net_handler_get(u32 msg_type, u32 key)
{
	struct o2net_msg_handler *nmh;

	read_lock(&o2net_handler_lock);
	nmh = o2net_handler_tree_lookup(msg_type, key, NULL, NULL);
	if (nmh)
		kref_get(&nmh->nh_kref);
	read_unlock(&o2net_handler_lock);

	return nmh;
}

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

static int o2net_recv_tcp_msg(struct socket *sock, void *data, size_t len)
{
	int ret;
	mm_segment_t oldfs;
	struct kvec vec = {
		.iov_len = len,
		.iov_base = data,
	};
	struct msghdr msg = {
		.msg_iovlen = 1,
		.msg_iov = (struct iovec *)&vec,
       		.msg_flags = MSG_DONTWAIT,
	};

	oldfs = get_fs();
	set_fs(get_ds());
	ret = sock_recvmsg(sock, &msg, len, msg.msg_flags);
	set_fs(oldfs);

	return ret;
}

static int o2net_send_tcp_msg(struct socket *sock, struct kvec *vec,
			      size_t veclen, size_t total)
{
	int ret;
	mm_segment_t oldfs;
	struct msghdr msg = {
		.msg_iov = (struct iovec *)vec,
		.msg_iovlen = veclen,
	};

	if (sock == NULL) {
		ret = -EINVAL;
		goto out;
	}

	oldfs = get_fs();
	set_fs(get_ds());
	ret = sock_sendmsg(sock, &msg, total);
	set_fs(oldfs);
	if (ret != total) {
		mlog(ML_ERROR, "sendmsg returned %d instead of %zu\n", ret,
		     total);
		if (ret >= 0)
			ret = -EPIPE; /* should be smarter, I bet */
		goto out;
	}

	ret = 0;
out:
	if (ret < 0)
		mlog(0, "returning error: %d\n", ret);
	return ret;
}

static void o2net_sendpage(struct o2net_sock_container *sc,
			   void *kmalloced_virt,
			   size_t size)
{
	struct o2net_node *nn = o2net_nn_from_num(sc->sc_node->nd_num);
	ssize_t ret;

	while (1) {
		mutex_lock(&sc->sc_send_lock);
		ret = sc->sc_sock->ops->sendpage(sc->sc_sock,
						 virt_to_page(kmalloced_virt),
						 (long)kmalloced_virt & ~PAGE_MASK,
						 size, MSG_DONTWAIT);
		mutex_unlock(&sc->sc_send_lock);
		if (ret == size)
			break;
		if (ret == (ssize_t)-EAGAIN) {
			mlog(0, "sendpage of size %zu to " SC_NODEF_FMT
			     " returned EAGAIN\n", size, SC_NODEF_ARGS(sc));
			cond_resched();
			continue;
		}
		mlog(ML_ERROR, "sendpage of size %zu to " SC_NODEF_FMT 
		     " failed with %zd\n", size, SC_NODEF_ARGS(sc), ret);
		o2net_ensure_shutdown(nn, sc, 0);
		break;
	}
}

static void o2net_init_msg(struct o2net_msg *msg, u16 data_len, u16 msg_type, u32 key)
{
	memset(msg, 0, sizeof(struct o2net_msg));
	msg->magic = cpu_to_be16(O2NET_MSG_MAGIC);
	msg->data_len = cpu_to_be16(data_len);
	msg->msg_type = cpu_to_be16(msg_type);
	msg->sys_status = cpu_to_be32(O2NET_ERR_NONE);
	msg->status = 0;
	msg->key = cpu_to_be32(key);
}

static int o2net_tx_can_proceed(struct o2net_node *nn,
			        struct o2net_sock_container **sc_ret,
				int *error)
{
	int ret = 0;

	spin_lock(&nn->nn_lock);
	if (nn->nn_persistent_error) {
		ret = 1;
		*sc_ret = NULL;
		*error = nn->nn_persistent_error;
	} else if (nn->nn_sc_valid) {
		kref_get(&nn->nn_sc->sc_kref);

		ret = 1;
		*sc_ret = nn->nn_sc;
		*error = 0;
	}
	spin_unlock(&nn->nn_lock);

	return ret;
}

int o2net_send_message_vec(u32 msg_type, u32 key, struct kvec *caller_vec,
			   size_t caller_veclen, u8 target_node, int *status)
{
	int ret, error = 0;
	struct o2net_msg *msg = NULL;
	size_t veclen, caller_bytes = 0;
	struct kvec *vec = NULL;
	struct o2net_sock_container *sc = NULL;
	struct o2net_node *nn = o2net_nn_from_num(target_node);
	struct o2net_status_wait nsw = {
		.ns_node_item = LIST_HEAD_INIT(nsw.ns_node_item),
	};

	if (o2net_wq == NULL) {
		mlog(0, "attempt to tx without o2netd running\n");
		ret = -ESRCH;
		goto out;
	}

	if (caller_veclen == 0) {
		mlog(0, "bad kvec array length\n");
		ret = -EINVAL;
		goto out;
	}

	caller_bytes = iov_length((struct iovec *)caller_vec, caller_veclen);
	if (caller_bytes > O2NET_MAX_PAYLOAD_BYTES) {
		mlog(0, "total payload len %zu too large\n", caller_bytes);
		ret = -EINVAL;
		goto out;
	}

	if (target_node == o2nm_this_node()) {
		ret = -ELOOP;
		goto out;
	}

	ret = wait_event_interruptible(nn->nn_sc_wq,
				       o2net_tx_can_proceed(nn, &sc, &error));
	if (!ret && error)
		ret = error;
	if (ret)
		goto out;

	veclen = caller_veclen + 1;
	vec = kmalloc(sizeof(struct kvec) * veclen, GFP_ATOMIC);
	if (vec == NULL) {
		mlog(0, "failed to %zu element kvec!\n", veclen);
		ret = -ENOMEM;
		goto out;
	}

	msg = kmalloc(sizeof(struct o2net_msg), GFP_ATOMIC);
	if (!msg) {
		mlog(0, "failed to allocate a o2net_msg!\n");
		ret = -ENOMEM;
		goto out;
	}

	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 */
	mutex_lock(&sc->sc_send_lock);
	ret = o2net_send_tcp_msg(sc->sc_sock, vec, veclen,
				 sizeof(struct o2net_msg) + caller_bytes);
	mutex_unlock(&sc->sc_send_lock);
	msglog(msg, "sending returned %d\n", ret);
	if (ret < 0) {
		mlog(0, "error returned from o2net_send_tcp_msg=%d\n", ret);