ar-ack.c

linux 内核源代码

			skb->mark = RXRPC_SKB_MARK_DATA;
			terminal = ((sp->hdr.flags & RXRPC_LAST_PACKET) &&
				!(sp->hdr.flags & RXRPC_CLIENT_INITIATED));
			ret = rxrpc_queue_rcv_skb(call, skb, true, terminal);
			BUG_ON(ret < 0);
			_debug("drain #%u", call->rx_data_post);
			call->rx_data_post++;

			/* find out what the next packet is */
			skb = skb_peek(&call->rx_oos_queue);
			if (skb)
				call->rx_first_oos =
					ntohl(rxrpc_skb(skb)->hdr.seq);
			else
				call->rx_first_oos = 0;
			_debug("peek %p {%u}", skb, call->rx_first_oos);
		}
	}

	ret = 0;
socket_unavailable:
	spin_unlock_bh(&call->lock);
	_leave(" = %d", ret);
	return ret;
}

/*
 * insert an out of sequence packet into the buffer
 */
static void rxrpc_insert_oos_packet(struct rxrpc_call *call,
				    struct sk_buff *skb)
{
	struct rxrpc_skb_priv *sp, *psp;
	struct sk_buff *p;
	u32 seq;

	sp = rxrpc_skb(skb);
	seq = ntohl(sp->hdr.seq);
	_enter(",,{%u}", seq);

	skb->destructor = rxrpc_packet_destructor;
	ASSERTCMP(sp->call, ==, NULL);
	sp->call = call;
	rxrpc_get_call(call);

	/* insert into the buffer in sequence order */
	spin_lock_bh(&call->lock);

	skb_queue_walk(&call->rx_oos_queue, p) {
		psp = rxrpc_skb(p);
		if (ntohl(psp->hdr.seq) > seq) {
			_debug("insert oos #%u before #%u",
			       seq, ntohl(psp->hdr.seq));
			skb_insert(p, skb, &call->rx_oos_queue);
			goto inserted;
		}
	}

	_debug("append oos #%u", seq);
	skb_queue_tail(&call->rx_oos_queue, skb);
inserted:

	/* we might now have a new front to the queue */
	if (call->rx_first_oos == 0 || seq < call->rx_first_oos)
		call->rx_first_oos = seq;

	read_lock(&call->state_lock);
	if (call->state < RXRPC_CALL_COMPLETE &&
	    call->rx_data_post == call->rx_first_oos) {
		_debug("drain rx oos now");
		set_bit(RXRPC_CALL_DRAIN_RX_OOS, &call->events);
	}
	read_unlock(&call->state_lock);

	spin_unlock_bh(&call->lock);
	_leave(" [stored #%u]", call->rx_first_oos);
}

/*
 * clear the Tx window on final ACK reception
 */
static void rxrpc_zap_tx_window(struct rxrpc_call *call)
{
	struct rxrpc_skb_priv *sp;
	struct sk_buff *skb;
	unsigned long _skb, *acks_window;
	uint8_t winsz = call->acks_winsz;
	int tail;

	acks_window = call->acks_window;
	call->acks_window = NULL;

	while (CIRC_CNT(call->acks_head, call->acks_tail, winsz) > 0) {
		tail = call->acks_tail;
		smp_read_barrier_depends();
		_skb = acks_window[tail] & ~1;
		smp_mb();
		call->acks_tail = (call->acks_tail + 1) & (winsz - 1);

		skb = (struct sk_buff *) _skb;
		sp = rxrpc_skb(skb);
		_debug("+++ clear Tx %u", ntohl(sp->hdr.seq));
		rxrpc_free_skb(skb);
	}

	kfree(acks_window);
}

/*
 * process the extra information that may be appended to an ACK packet
 */
static void rxrpc_extract_ackinfo(struct rxrpc_call *call, struct sk_buff *skb,
				  unsigned latest, int nAcks)
{
	struct rxrpc_ackinfo ackinfo;
	struct rxrpc_peer *peer;
	unsigned mtu;

	if (skb_copy_bits(skb, nAcks + 3, &ackinfo, sizeof(ackinfo)) < 0) {
		_leave(" [no ackinfo]");
		return;
	}

	_proto("Rx ACK %%%u Info { rx=%u max=%u rwin=%u jm=%u }",
	       latest,
	       ntohl(ackinfo.rxMTU), ntohl(ackinfo.maxMTU),
	       ntohl(ackinfo.rwind), ntohl(ackinfo.jumbo_max));

	mtu = min(ntohl(ackinfo.rxMTU), ntohl(ackinfo.maxMTU));

	peer = call->conn->trans->peer;
	if (mtu < peer->maxdata) {
		spin_lock_bh(&peer->lock);
		peer->maxdata = mtu;
		peer->mtu = mtu + peer->hdrsize;
		spin_unlock_bh(&peer->lock);
		_net("Net MTU %u (maxdata %u)", peer->mtu, peer->maxdata);
	}
}

/*
 * process packets in the reception queue
 */
static int rxrpc_process_rx_queue(struct rxrpc_call *call,
				  u32 *_abort_code)
{
	struct rxrpc_ackpacket ack;
	struct rxrpc_skb_priv *sp;
	struct sk_buff *skb;
	bool post_ACK;
	int latest;
	u32 hard, tx;

	_enter("");

process_further:
	skb = skb_dequeue(&call->rx_queue);
	if (!skb)
		return -EAGAIN;

	_net("deferred skb %p", skb);

	sp = rxrpc_skb(skb);

	_debug("process %s [st %d]", rxrpc_pkts[sp->hdr.type], call->state);

	post_ACK = false;

	switch (sp->hdr.type) {
		/* data packets that wind up here have been received out of
		 * order, need security processing or are jumbo packets */
	case RXRPC_PACKET_TYPE_DATA:
		_proto("OOSQ DATA %%%u { #%u }",
		       ntohl(sp->hdr.serial), ntohl(sp->hdr.seq));

		/* secured packets must be verified and possibly decrypted */
		if (rxrpc_verify_packet(call, skb, _abort_code) < 0)
			goto protocol_error;

		rxrpc_insert_oos_packet(call, skb);
		goto process_further;

		/* partial ACK to process */
	case RXRPC_PACKET_TYPE_ACK:
		if (skb_copy_bits(skb, 0, &ack, sizeof(ack)) < 0) {
			_debug("extraction failure");
			goto protocol_error;
		}
		if (!skb_pull(skb, sizeof(ack)))
			BUG();

		latest = ntohl(sp->hdr.serial);
		hard = ntohl(ack.firstPacket);
		tx = atomic_read(&call->sequence);

		_proto("Rx ACK %%%u { m=%hu f=#%u p=#%u s=%%%u r=%s n=%u }",
		       latest,
		       ntohs(ack.maxSkew),
		       hard,
		       ntohl(ack.previousPacket),
		       ntohl(ack.serial),
		       rxrpc_acks[ack.reason],
		       ack.nAcks);

		rxrpc_extract_ackinfo(call, skb, latest, ack.nAcks);

		if (ack.reason == RXRPC_ACK_PING) {
			_proto("Rx ACK %%%u PING Request", latest);
			rxrpc_propose_ACK(call, RXRPC_ACK_PING_RESPONSE,
					  sp->hdr.serial, true);
		}

		/* discard any out-of-order or duplicate ACKs */
		if (latest - call->acks_latest <= 0) {
			_debug("discard ACK %d <= %d",
			       latest, call->acks_latest);
			goto discard;
		}
		call->acks_latest = latest;

		if (call->state != RXRPC_CALL_CLIENT_SEND_REQUEST &&
		    call->state != RXRPC_CALL_CLIENT_AWAIT_REPLY &&
		    call->state != RXRPC_CALL_SERVER_SEND_REPLY &&
		    call->state != RXRPC_CALL_SERVER_AWAIT_ACK)
			goto discard;

		_debug("Tx=%d H=%u S=%d", tx, call->acks_hard, call->state);

		if (hard > 0) {
			if (hard - 1 > tx) {
				_debug("hard-ACK'd packet %d not transmitted"
				       " (%d top)",
				       hard - 1, tx);
				goto protocol_error;
			}

			if ((call->state == RXRPC_CALL_CLIENT_AWAIT_REPLY ||
			     call->state == RXRPC_CALL_SERVER_AWAIT_ACK) &&
			    hard > tx)
				goto all_acked;

			smp_rmb();
			rxrpc_rotate_tx_window(call, hard - 1);
		}

		if (ack.nAcks > 0) {
			if (hard - 1 + ack.nAcks > tx) {
				_debug("soft-ACK'd packet %d+%d not"
				       " transmitted (%d top)",
				       hard - 1, ack.nAcks, tx);
				goto protocol_error;
			}

			if (rxrpc_process_soft_ACKs(call, &ack, skb) < 0)
				goto protocol_error;
		}
		goto discard;

		/* complete ACK to process */
	case RXRPC_PACKET_TYPE_ACKALL:
		goto all_acked;

		/* abort and busy are handled elsewhere */
	case RXRPC_PACKET_TYPE_BUSY:
	case RXRPC_PACKET_TYPE_ABORT:
		BUG();

		/* connection level events - also handled elsewhere */
	case RXRPC_PACKET_TYPE_CHALLENGE:
	case RXRPC_PACKET_TYPE_RESPONSE:
	case RXRPC_PACKET_TYPE_DEBUG:
		BUG();
	}

	/* if we've had a hard ACK that covers all the packets we've sent, then
	 * that ends that phase of the operation */
all_acked:
	write_lock_bh(&call->state_lock);
	_debug("ack all %d", call->state);

	switch (call->state) {
	case RXRPC_CALL_CLIENT_AWAIT_REPLY:
		call->state = RXRPC_CALL_CLIENT_RECV_REPLY;
		break;
	case RXRPC_CALL_SERVER_AWAIT_ACK:
		_debug("srv complete");
		call->state = RXRPC_CALL_COMPLETE;
		post_ACK = true;
		break;
	case RXRPC_CALL_CLIENT_SEND_REQUEST:
	case RXRPC_CALL_SERVER_RECV_REQUEST:
		goto protocol_error_unlock; /* can't occur yet */
	default:
		write_unlock_bh(&call->state_lock);
		goto discard; /* assume packet left over from earlier phase */
	}

	write_unlock_bh(&call->state_lock);

	/* if all the packets we sent are hard-ACK'd, then we can discard
	 * whatever we've got left */
	_debug("clear Tx %d",
	       CIRC_CNT(call->acks_head, call->acks_tail, call->acks_winsz));

	del_timer_sync(&call->resend_timer);
	clear_bit(RXRPC_CALL_RUN_RTIMER, &call->flags);
	clear_bit(RXRPC_CALL_RESEND_TIMER, &call->events);

	if (call->acks_window)
		rxrpc_zap_tx_window(call);

	if (post_ACK) {
		/* post the final ACK message for userspace to pick up */
		_debug("post ACK");
		skb->mark = RXRPC_SKB_MARK_FINAL_ACK;
		sp->call = call;
		rxrpc_get_call(call);
		spin_lock_bh(&call->lock);
		if (rxrpc_queue_rcv_skb(call, skb, true, true) < 0)
			BUG();
		spin_unlock_bh(&call->lock);
		goto process_further;
	}

discard:
	rxrpc_free_skb(skb);
	goto process_further;

protocol_error_unlock:
	write_unlock_bh(&call->state_lock);
protocol_error:
	rxrpc_free_skb(skb);
	_leave(" = -EPROTO");
	return -EPROTO;
}

/*
 * post a message to the socket Rx queue for recvmsg() to pick up
 */
static int rxrpc_post_message(struct rxrpc_call *call, u32 mark, u32 error,
			      bool fatal)
{
	struct rxrpc_skb_priv *sp;
	struct sk_buff *skb;
	int ret;

	_enter("{%d,%lx},%u,%u,%d",
	       call->debug_id, call->flags, mark, error, fatal);

	/* remove timers and things for fatal messages */
	if (fatal) {
		del_timer_sync(&call->resend_timer);
		del_timer_sync(&call->ack_timer);
		clear_bit(RXRPC_CALL_RUN_RTIMER, &call->flags);
	}

	if (mark != RXRPC_SKB_MARK_NEW_CALL &&
	    !test_bit(RXRPC_CALL_HAS_USERID, &call->flags)) {
		_leave("[no userid]");
		return 0;
	}

	if (!test_bit(RXRPC_CALL_TERMINAL_MSG, &call->flags)) {
		skb = alloc_skb(0, GFP_NOFS);
		if (!skb)
			return -ENOMEM;

		rxrpc_new_skb(skb);

		skb->mark = mark;

		sp = rxrpc_skb(skb);
		memset(sp, 0, sizeof(*sp));
		sp->error = error;
		sp->call = call;
		rxrpc_get_call(call);

		spin_lock_bh(&call->lock);
		ret = rxrpc_queue_rcv_skb(call, skb, true, fatal);
		spin_unlock_bh(&call->lock);
		if (ret < 0)
			BUG();
	}

	return 0;
}

/*
 * handle background processing of incoming call packets and ACK / abort
 * generation
 */
void rxrpc_process_call(struct work_struct *work)
{
	struct rxrpc_call *call =
		container_of(work, struct rxrpc_call, processor);
	struct rxrpc_ackpacket ack;
	struct rxrpc_ackinfo ackinfo;
	struct rxrpc_header hdr;
	struct msghdr msg;
	struct kvec iov[5];
	unsigned long bits;
	__be32 data, pad;
	size_t len;
	int genbit, loop, nbit, ioc, ret, mtu;
	u32 abort_code = RX_PROTOCOL_ERROR;
	u8 *acks = NULL;

	//printk("\n--------------------\n");
	_enter("{%d,%s,%lx} [%lu]",
	       call->debug_id, rxrpc_call_states[call->state], call->events,
	       (jiffies - call->creation_jif) / (HZ / 10));

	if (test_and_set_bit(RXRPC_CALL_PROC_BUSY, &call->flags)) {
		_debug("XXXXXXXXXXXXX RUNNING ON MULTIPLE CPUS XXXXXXXXXXXXX");
		return;
	}

	/* there's a good chance we're going to have to send a message, so set
	 * one up in advance */
	msg.msg_name	= &call->conn->trans->peer->srx.transport.sin;
	msg.msg_namelen	= sizeof(call->conn->trans->peer->srx.transport.sin);
	msg.msg_control	= NULL;
	msg.msg_controllen = 0;
	msg.msg_flags	= 0;

	hdr.epoch	= call->conn->epoch;
	hdr.cid		= call->cid;
	hdr.callNumber	= call->call_id;
	hdr.seq		= 0;
	hdr.type	= RXRPC_PACKET_TYPE_ACK;
	hdr.flags	= call->conn->out_clientflag;
	hdr.userStatus	= 0;
	hdr.securityIndex = call->conn->security_ix;
	hdr._rsvd	= 0;
	hdr.serviceId	= call->conn->service_id;