// SPDX-License-Identifier: GPL-2.0 OR Linux-OpenIB
/*
 * Copyright (c) 2016 Mellanox Technologies Ltd. All rights reserved.
 * Copyright (c) 2015 System Fabric Works, Inc. All rights reserved.
 */

#include <linux/skbuff.h>

#include "rxe.h"
#include "rxe_loc.h"
#include "rxe_queue.h"

static char *resp_state_name[] = {
	[RESPST_NONE]				= "NONE",
	[RESPST_GET_REQ]			= "GET_REQ",
	[RESPST_CHK_PSN]			= "CHK_PSN",
	[RESPST_CHK_OP_SEQ]			= "CHK_OP_SEQ",
	[RESPST_CHK_OP_VALID]			= "CHK_OP_VALID",
	[RESPST_CHK_RESOURCE]			= "CHK_RESOURCE",
	[RESPST_CHK_LENGTH]			= "CHK_LENGTH",
	[RESPST_CHK_RKEY]			= "CHK_RKEY",
	[RESPST_EXECUTE]			= "EXECUTE",
	[RESPST_READ_REPLY]			= "READ_REPLY",
	[RESPST_ATOMIC_REPLY]			= "ATOMIC_REPLY",
	[RESPST_ATOMIC_WRITE_REPLY]		= "ATOMIC_WRITE_REPLY",
	[RESPST_PROCESS_FLUSH]			= "PROCESS_FLUSH",
	[RESPST_COMPLETE]			= "COMPLETE",
	[RESPST_ACKNOWLEDGE]			= "ACKNOWLEDGE",
	[RESPST_CLEANUP]			= "CLEANUP",
	[RESPST_DUPLICATE_REQUEST]		= "DUPLICATE_REQUEST",
	[RESPST_ERR_MALFORMED_WQE]		= "ERR_MALFORMED_WQE",
	[RESPST_ERR_UNSUPPORTED_OPCODE]		= "ERR_UNSUPPORTED_OPCODE",
	[RESPST_ERR_MISALIGNED_ATOMIC]		= "ERR_MISALIGNED_ATOMIC",
	[RESPST_ERR_PSN_OUT_OF_SEQ]		= "ERR_PSN_OUT_OF_SEQ",
	[RESPST_ERR_MISSING_OPCODE_FIRST]	= "ERR_MISSING_OPCODE_FIRST",
	[RESPST_ERR_MISSING_OPCODE_LAST_C]	= "ERR_MISSING_OPCODE_LAST_C",
	[RESPST_ERR_MISSING_OPCODE_LAST_D1E]	= "ERR_MISSING_OPCODE_LAST_D1E",
	[RESPST_ERR_TOO_MANY_RDMA_ATM_REQ]	= "ERR_TOO_MANY_RDMA_ATM_REQ",
	[RESPST_ERR_RNR]			= "ERR_RNR",
	[RESPST_ERR_RKEY_VIOLATION]		= "ERR_RKEY_VIOLATION",
	[RESPST_ERR_INVALIDATE_RKEY]		= "ERR_INVALIDATE_RKEY_VIOLATION",
	[RESPST_ERR_LENGTH]			= "ERR_LENGTH",
	[RESPST_ERR_CQ_OVERFLOW]		= "ERR_CQ_OVERFLOW",
	[RESPST_ERROR]				= "ERROR",
	[RESPST_DONE]				= "DONE",
	[RESPST_EXIT]				= "EXIT",
};

/* rxe_recv calls here to add a request packet to the input queue */
void rxe_resp_queue_pkt(struct rxe_qp *qp, struct sk_buff *skb)
{
	int must_sched;
	struct rxe_pkt_info *pkt = SKB_TO_PKT(skb);

	skb_queue_tail(&qp->req_pkts, skb);

	must_sched = (pkt->opcode == IB_OPCODE_RC_RDMA_READ_REQUEST) ||
			(skb_queue_len(&qp->req_pkts) > 1);

	if (must_sched)
		rxe_sched_task(&qp->resp.task);
	else
		rxe_run_task(&qp->resp.task);
}

static inline enum resp_states get_req(struct rxe_qp *qp,
				       struct rxe_pkt_info **pkt_p)
{
	struct sk_buff *skb;

	skb = skb_peek(&qp->req_pkts);
	if (!skb)
		return RESPST_EXIT;

	*pkt_p = SKB_TO_PKT(skb);

	return (qp->resp.res) ? RESPST_READ_REPLY : RESPST_CHK_PSN;
}

static enum resp_states check_psn(struct rxe_qp *qp,
				  struct rxe_pkt_info *pkt)
{
	int diff = psn_compare(pkt->psn, qp->resp.psn);
	struct rxe_dev *rxe = to_rdev(qp->ibqp.device);

	switch (qp_type(qp)) {
	case IB_QPT_RC:
		if (diff > 0) {
			if (qp->resp.sent_psn_nak)
				return RESPST_CLEANUP;

			qp->resp.sent_psn_nak = 1;
			rxe_counter_inc(rxe, RXE_CNT_OUT_OF_SEQ_REQ);
			return RESPST_ERR_PSN_OUT_OF_SEQ;

		} else if (diff < 0) {
			rxe_counter_inc(rxe, RXE_CNT_DUP_REQ);
			return RESPST_DUPLICATE_REQUEST;
		}

		if (qp->resp.sent_psn_nak)
			qp->resp.sent_psn_nak = 0;

		break;

	case IB_QPT_UC:
		if (qp->resp.drop_msg || diff != 0) {
			if (pkt->mask & RXE_START_MASK) {
				qp->resp.drop_msg = 0;
				return RESPST_CHK_OP_SEQ;
			}

			qp->resp.drop_msg = 1;
			return RESPST_CLEANUP;
		}
		break;
	default:
		break;
	}

	return RESPST_CHK_OP_SEQ;
}

static enum resp_states check_op_seq(struct rxe_qp *qp,
				     struct rxe_pkt_info *pkt)
{
	switch (qp_type(qp)) {
	case IB_QPT_RC:
		switch (qp->resp.opcode) {
		case IB_OPCODE_RC_SEND_FIRST:
		case IB_OPCODE_RC_SEND_MIDDLE:
			switch (pkt->opcode) {
			case IB_OPCODE_RC_SEND_MIDDLE:
			case IB_OPCODE_RC_SEND_LAST:
			case IB_OPCODE_RC_SEND_LAST_WITH_IMMEDIATE:
			case IB_OPCODE_RC_SEND_LAST_WITH_INVALIDATE:
				return RESPST_CHK_OP_VALID;
			default:
				return RESPST_ERR_MISSING_OPCODE_LAST_C;
			}

		case IB_OPCODE_RC_RDMA_WRITE_FIRST:
		case IB_OPCODE_RC_RDMA_WRITE_MIDDLE:
			switch (pkt->opcode) {
			case IB_OPCODE_RC_RDMA_WRITE_MIDDLE:
			case IB_OPCODE_RC_RDMA_WRITE_LAST:
			case IB_OPCODE_RC_RDMA_WRITE_LAST_WITH_IMMEDIATE:
				return RESPST_CHK_OP_VALID;
			default:
				return RESPST_ERR_MISSING_OPCODE_LAST_C;
			}

		default:
			switch (pkt->opcode) {
			case IB_OPCODE_RC_SEND_MIDDLE:
			case IB_OPCODE_RC_SEND_LAST:
			case IB_OPCODE_RC_SEND_LAST_WITH_IMMEDIATE:
			case IB_OPCODE_RC_SEND_LAST_WITH_INVALIDATE:
			case IB_OPCODE_RC_RDMA_WRITE_MIDDLE:
			case IB_OPCODE_RC_RDMA_WRITE_LAST:
			case IB_OPCODE_RC_RDMA_WRITE_LAST_WITH_IMMEDIATE:
				return RESPST_ERR_MISSING_OPCODE_FIRST;
			default:
				return RESPST_CHK_OP_VALID;
			}
		}
		break;

	case IB_QPT_UC:
		switch (qp->resp.opcode) {
		case IB_OPCODE_UC_SEND_FIRST:
		case IB_OPCODE_UC_SEND_MIDDLE:
			switch (pkt->opcode) {
			case IB_OPCODE_UC_SEND_MIDDLE:
			case IB_OPCODE_UC_SEND_LAST:
			case IB_OPCODE_UC_SEND_LAST_WITH_IMMEDIATE:
				return RESPST_CHK_OP_VALID;
			default:
				return RESPST_ERR_MISSING_OPCODE_LAST_D1E;
			}

		case IB_OPCODE_UC_RDMA_WRITE_FIRST:
		case IB_OPCODE_UC_RDMA_WRITE_MIDDLE:
			switch (pkt->opcode) {
			case IB_OPCODE_UC_RDMA_WRITE_MIDDLE:
			case IB_OPCODE_UC_RDMA_WRITE_LAST:
			case IB_OPCODE_UC_RDMA_WRITE_LAST_WITH_IMMEDIATE:
				return RESPST_CHK_OP_VALID;
			default:
				return RESPST_ERR_MISSING_OPCODE_LAST_D1E;
			}

		default:
			switch (pkt->opcode) {
			case IB_OPCODE_UC_SEND_MIDDLE:
			case IB_OPCODE_UC_SEND_LAST:
			case IB_OPCODE_UC_SEND_LAST_WITH_IMMEDIATE:
			case IB_OPCODE_UC_RDMA_WRITE_MIDDLE:
			case IB_OPCODE_UC_RDMA_WRITE_LAST:
			case IB_OPCODE_UC_RDMA_WRITE_LAST_WITH_IMMEDIATE:
				qp->resp.drop_msg = 1;
				return RESPST_CLEANUP;
			default:
				return RESPST_CHK_OP_VALID;
			}
		}
		break;

	default:
		return RESPST_CHK_OP_VALID;
	}
}

static bool check_qp_attr_access(struct rxe_qp *qp,
				 struct rxe_pkt_info *pkt)
{
	if (((pkt->mask & RXE_READ_MASK) &&
	     !(qp->attr.qp_access_flags & IB_ACCESS_REMOTE_READ)) ||
	    ((pkt->mask & (RXE_WRITE_MASK | RXE_ATOMIC_WRITE_MASK)) &&
	     !(qp->attr.qp_access_flags & IB_ACCESS_REMOTE_WRITE)) ||
	    ((pkt->mask & RXE_ATOMIC_MASK) &&
	     !(qp->attr.qp_access_flags & IB_ACCESS_REMOTE_ATOMIC)))
		return false;

	if (pkt->mask & RXE_FLUSH_MASK) {
		u32 flush_type = feth_plt(pkt);

		if ((flush_type & IB_FLUSH_GLOBAL &&
		     !(qp->attr.qp_access_flags & IB_ACCESS_FLUSH_GLOBAL)) ||
		    (flush_type & IB_FLUSH_PERSISTENT &&
		     !(qp->attr.qp_access_flags & IB_ACCESS_FLUSH_PERSISTENT)))
			return false;
	}

	return true;
}

static enum resp_states check_op_valid(struct rxe_qp *qp,
				       struct rxe_pkt_info *pkt)
{
	switch (qp_type(qp)) {
	case IB_QPT_RC:
		if (!check_qp_attr_access(qp, pkt))
			return RESPST_ERR_UNSUPPORTED_OPCODE;

		break;

	case IB_QPT_UC:
		if ((pkt->mask & RXE_WRITE_MASK) &&
		    !(qp->attr.qp_access_flags & IB_ACCESS_REMOTE_WRITE)) {
			qp->resp.drop_msg = 1;
			return RESPST_CLEANUP;
		}

		break;

	case IB_QPT_UD:
	case IB_QPT_GSI:
		break;

	default:
		WARN_ON_ONCE(1);
		break;
	}

	return RESPST_CHK_RESOURCE;
}

static enum resp_states get_srq_wqe(struct rxe_qp *qp)
{
	struct rxe_srq *srq = qp->srq;
	struct rxe_queue *q = srq->rq.queue;
	struct rxe_recv_wqe *wqe;
	struct ib_event ev;
	unsigned int count;
	size_t size;
	unsigned long flags;

	if (srq->error)
		return RESPST_ERR_RNR;

	spin_lock_irqsave(&srq->rq.consumer_lock, flags);

	wqe = queue_head(q, QUEUE_TYPE_FROM_CLIENT);
	if (!wqe) {
		spin_unlock_irqrestore(&srq->rq.consumer_lock, flags);
		return RESPST_ERR_RNR;
	}

	/* don't trust user space data */
	if (unlikely(wqe->dma.num_sge > srq->rq.max_sge)) {
		spin_unlock_irqrestore(&srq->rq.consumer_lock, flags);
		rxe_dbg_qp(qp, "invalid num_sge in SRQ entry\n");
		return RESPST_ERR_MALFORMED_WQE;
	}
	size = sizeof(*wqe) + wqe->dma.num_sge*sizeof(struct rxe_sge);
	memcpy(&qp->resp.srq_wqe, wqe, size);

	qp->resp.wqe = &qp->resp.srq_wqe.wqe;
	queue_advance_consumer(q, QUEUE_TYPE_FROM_CLIENT);
	count = queue_count(q, QUEUE_TYPE_FROM_CLIENT);

	if (srq->limit && srq->ibsrq.event_handler && (count < srq->limit)) {
		srq->limit = 0;
		goto event;
	}

	spin_unlock_irqrestore(&srq->rq.consumer_lock, flags);
	return RESPST_CHK_LENGTH;

event:
	spin_unlock_irqrestore(&srq->rq.consumer_lock, flags);
	ev.device = qp->ibqp.device;
	ev.element.srq = qp->ibqp.srq;
	ev.event = IB_EVENT_SRQ_LIMIT_REACHED;
	srq->ibsrq.event_handler(&ev, srq->ibsrq.srq_context);
	return RESPST_CHK_LENGTH;
}

static enum resp_states check_resource(struct rxe_qp *qp,
				       struct rxe_pkt_info *pkt)
{
	struct rxe_srq *srq = qp->srq;

	if (pkt->mask & (RXE_READ_OR_ATOMIC_MASK | RXE_ATOMIC_WRITE_MASK)) {
		/* it is the requesters job to not send
		 * too many read/atomic ops, we just
		 * recycle the responder resource queue
		 */
		if (likely(qp->attr.max_dest_rd_atomic > 0))
			return RESPST_CHK_LENGTH;
		else
			return RESPST_ERR_TOO_MANY_RDMA_ATM_REQ;
	}

	if (pkt->mask & RXE_RWR_MASK) {
		if (srq)
			return get_srq_wqe(qp);

		qp->resp.wqe = queue_head(qp->rq.queue,
				QUEUE_TYPE_FROM_CLIENT);
		return (qp->resp.wqe) ? RESPST_CHK_LENGTH : RESPST_ERR_RNR;
	}

	return RESPST_CHK_LENGTH;
}

static enum resp_states rxe_resp_check_length(struct rxe_qp *qp,
					      struct rxe_pkt_info *pkt)
{
	/*
	 * See IBA C9-92
	 * For UD QPs we only check if the packet will fit in the
	 * receive buffer later. For rmda operations additional
	 * length checks are performed in check_rkey.
	 */
	if ((qp_type(qp) == IB_QPT_GSI) || (qp_type(qp) == IB_QPT_UD)) {
		unsigned int payload = payload_size(pkt);
		unsigned int recv_buffer_len = 0;
		int i;

		for (i = 0; i < qp->resp.wqe->dma.num_sge; i++)
			recv_buffer_len += qp->resp.wqe->dma.sge[i].length;
		if (payload + 40 > recv_buffer_len) {
			rxe_dbg_qp(qp, "The receive buffer is too small for this UD packet.\n");
			return RESPST_ERR_LENGTH;
		}
	}

	if (pkt->mask & RXE_PAYLOAD_MASK && ((qp_type(qp) == IB_QPT_RC) ||
					     (qp_type(qp) == IB_QPT_UC))) {
		unsigned int mtu = qp->mtu;
		unsigned int payload = payload_size(pkt);

		if ((pkt->mask & RXE_START_MASK) &&
		    (pkt->mask & RXE_END_MASK)) {
			if (unlikely(payload > mtu)) {
				rxe_dbg_qp(qp, "only packet too long");
				return RESPST_ERR_LENGTH;
			}
		} else if ((pkt->mask & RXE_START_MASK) ||
			   (pkt->mask & RXE_MIDDLE_MASK)) {
			if (unlikely(payload != mtu)) {
				rxe_dbg_qp(qp, "first or middle packet not mtu");
				return RESPST_ERR_LENGTH;
			}
		} else if (pkt->mask & RXE_END_MASK) {
			if (unlikely((payload == 0) || (payload > mtu))) {
				rxe_dbg_qp(qp, "last packet zero or too long");
				return RESPST_ERR_LENGTH;
			}
		}
	}

	/* See IBA C9-94 */
	if (pkt->mask & RXE_RETH_MASK) {
		if (reth_len(pkt) > (1U << 31)) {
			rxe_dbg_qp(qp, "dma length too long");
			return RESPST_ERR_LENGTH;
		}
	}

	if (pkt->mask & RXE_RDMA_OP_MASK)
		return RESPST_CHK_RKEY;
	else
		return RESPST_EXECUTE;
}

/* if the reth length field is zero we can assume nothing
 * about the rkey value and should not validate or use it.
 * Instead set qp->resp.rkey to 0 which is an invalid rkey
 * value since the minimum index part is 1.
 */
static void qp_resp_from_reth(struct rxe_qp *qp, struct rxe_pkt_info *pkt)
{
	unsigned int length = reth_len(pkt);

	qp->resp.va = reth_va(pkt);
	qp->resp.offset = 0;
	qp->resp.resid = length;
	qp->resp.length = length;
	if (pkt->mask & RXE_READ_OR_WRITE_MASK && length == 0)
		qp->resp.rkey = 0;
	else
		qp->resp.rkey = reth_rkey(pkt);
}

static void qp_resp_from_atmeth(struct rxe_qp *qp, struct rxe_pkt_info *pkt)
{
	qp->resp.va = atmeth_va(pkt);
	qp->resp.offset = 0;
	qp->resp.rkey = atmeth_rkey(pkt);
	qp->resp.resid = sizeof(u64);
}

/* resolve the packet rkey to qp->resp.mr or set qp->resp.mr to NULL
 * if an invalid rkey is received or the rdma length is zero. For middle
 * or last packets use the stored value of mr.
 */
static enum resp_states check_rkey(struct rxe_qp *qp,
				   struct rxe_pkt_info *pkt)
{
	struct rxe_mr *mr = NULL;
	struct rxe_mw *mw = NULL;
	u64 va;
	u32 rkey;
	u32 resid;
	u32 pktlen;
	int mtu = qp->mtu;
	enum resp_states state;
	int access = 0;

	/* parse RETH or ATMETH header for first/only packets
	 * for va, length, rkey, etc. or use current value for
	 * middle/last packets.
	 */
	if (pkt->mask & (RXE_READ_OR_WRITE_MASK | RXE_ATOMIC_WRITE_MASK)) {
		if (pkt->mask & RXE_RETH_MASK)
			qp_resp_from_reth(qp, pkt);

		access = (pkt->mask & RXE_READ_MASK) ? IB_ACCESS_REMOTE_READ
						     : IB_ACCESS_REMOTE_WRITE;
	} else if (pkt->mask & RXE_FLUSH_MASK) {
		u32 flush_type = feth_plt(pkt);

		if (pkt->mask & RXE_RETH_MASK)
			qp_resp_from_reth(qp, pkt);

		if (flush_type & IB_FLUSH_GLOBAL)
			access |= IB_ACCESS_FLUSH_GLOBAL;
		if (flush_type & IB_FLUSH_PERSISTENT)
			access |= IB_ACCESS_FLUSH_PERSISTENT;
	} else if (pkt->mask & RXE_ATOMIC_MASK) {
		qp_resp_from_atmeth(qp, pkt);
		access = IB_ACCESS_REMOTE_ATOMIC;
	} else {
		/* shouldn't happen */
		WARN_ON(1);
	}

	/* A zero-byte read or write op is not required to
	 * set an addr or rkey. See C9-88
	 */
	if ((pkt->mask & RXE_READ_OR_WRITE_MASK) &&
	    (pkt->mask & RXE_RETH_MASK) && reth_len(pkt) == 0) {
		qp->resp.mr = NULL;
		return RESPST_EXECUTE;
	}

	va	= qp->resp.va;
	rkey	= qp->resp.rkey;
	resid	= qp->resp.resid;
	pktlen	= payload_size(pkt);

	if (rkey_is_mw(rkey)) {
		mw = rxe_lookup_mw(qp, access, rkey);
		if (!mw) {
			rxe_dbg_qp(qp, "no MW matches rkey %#x\n", rkey);
			state = RESPST_ERR_RKEY_VIOLATION;
			goto err;
		}

		mr = mw->mr;
		if (!mr) {
			rxe_dbg_qp(qp, "MW doesn't have an MR\n");
			state = RESPST_ERR_RKEY_VIOLATION;
			goto err;
		}

		if (mw->access & IB_ZERO_BASED)
			qp->resp.offset = mw->addr;

		rxe_get(mr);
		rxe_put(mw);
		mw = NULL;
	} else {
		mr = lookup_mr(qp->pd, access, rkey, RXE_LOOKUP_REMOTE);
		if (!mr) {
			rxe_dbg_qp(qp, "no MR matches rkey %#x\n", rkey);
			state = RESPST_ERR_RKEY_VIOLATION;
			goto err;
		}
	}

	if (pkt->mask & RXE_FLUSH_MASK) {
		/* FLUSH MR may not set va or resid
		 * no need to check range since we will flush whole mr
		 */
		if (feth_sel(pkt) == IB_FLUSH_MR)
			goto skip_check_range;
	}

	if (mr_check_range(mr, va + qp->resp.offset, resid)) {
		state = RESPST_ERR_RKEY_VIOLATION;
		goto err;
	}

skip_check_range:
	if (pkt->mask & (RXE_WRITE_MASK | RXE_ATOMIC_WRITE_MASK)) {
		if (resid > mtu) {
			if (pktlen != mtu || bth_pad(pkt)) {
				state = RESPST_ERR_LENGTH;
				goto err;
			}
		} else {
			if (pktlen != resid) {
				state = RESPST_ERR_LENGTH;
				goto err;
			}
			if ((bth_pad(pkt) != (0x3 & (-resid)))) {
				/* This case may not be exactly that
				 * but nothing else fits.
				 */
				state = RESPST_ERR_LENGTH;
				goto err;
			}
		}
	}

	WARN_ON_ONCE(qp->resp.mr);

	qp->resp.mr = mr;
	return RESPST_EXECUTE;

err:
	qp->resp.mr = NULL;
	if (mr)
		rxe_put(mr);
	if (mw)
		rxe_put(mw);

	return state;
}

static enum resp_states send_data_in(struct rxe_qp *qp, void *data_addr,
				     int data_len)
{
	int err;

	err = copy_data(qp->pd, IB_ACCESS_LOCAL_WRITE, &qp->resp.wqe->dma,
			data_addr, data_len, RXE_TO_MR_OBJ);
	if (unlikely(err))
		return (err == -ENOSPC) ? RESPST_ERR_LENGTH
					: RESPST_ERR_MALFORMED_WQE;

	return RESPST_NONE;
}

static enum resp_states write_data_in(struct rxe_qp *qp,
				      struct rxe_pkt_info *pkt)
{
	enum resp_states rc = RESPST_NONE;
	int	err;
	int data_len = payload_size(pkt);

	err = rxe_mr_copy(qp->resp.mr, qp->resp.va + qp->resp.offset,
			  payload_addr(pkt), data_len, RXE_TO_MR_OBJ);
	if (err) {
		rc = RESPST_ERR_RKEY_VIOLATION;
		goto out;
	}

	qp->resp.va += data_len;
	qp->resp.resid -= data_len;

out:
	return rc;
}

static struct resp_res *rxe_prepare_res(struct rxe_qp *qp,
					struct rxe_pkt_info *pkt,
					int type)
{
	struct resp_res *res;
	u32 pkts;

	res = &qp->resp.resources[qp->resp.res_head];
	rxe_advance_resp_resource(qp);
	free_rd_atomic_resource(res);

	res->type = type;
	res->replay = 0;

	switch (type) {
	case RXE_READ_MASK:
		res->read.va = qp->resp.va + qp->resp.offset;
		res->read.va_org = qp->resp.va + qp->resp.offset;
		res->read.resid = qp->resp.resid;
		res->read.length = qp->resp.resid;
		res->read.rkey = qp->resp.rkey;

		pkts = max_t(u32, (reth_len(pkt) + qp->mtu - 1)/qp->mtu, 1);
		res->first_psn = pkt->psn;
		res->cur_psn = pkt->psn;
		res->last_psn = (pkt->psn + pkts - 1) & BTH_PSN_MASK;

		res->state = rdatm_res_state_new;
		break;
	case RXE_ATOMIC_MASK:
	case RXE_ATOMIC_WRITE_MASK:
		res->first_psn = pkt->psn;
		res->last_psn = pkt->psn;
		res->cur_psn = pkt->psn;
		break;
	case RXE_FLUSH_MASK:
		res->flush.va = qp->resp.va + qp->resp.offset;
		res->flush.length = qp->resp.length;
		res->flush.type = feth_plt(pkt);
		res->flush.level = feth_sel(pkt);
	}

	return res;
}

static enum resp_states process_flush(struct rxe_qp *qp,
				       struct rxe_pkt_info *pkt)
{
	u64 length, start;
	struct rxe_mr *mr = qp->resp.mr;
	struct resp_res *res = qp->resp.res;

	/* oA19-14, oA19-15 */
	if (res && res->replay)
		return RESPST_ACKNOWLEDGE;
	else if (!res) {
		res = rxe_prepare_res(qp, pkt, RXE_FLUSH_MASK);
		qp->resp.res = res;
	}

	if (res->flush.level == IB_FLUSH_RANGE) {
		start = res->flush.va;
		length = res->flush.length;
	} else { /* level == IB_FLUSH_MR */
		start = mr->ibmr.iova;
		length = mr->ibmr.length;
	}

	if (res->flush.type & IB_FLUSH_PERSISTENT) {
		if (rxe_flush_pmem_iova(mr, start, length))
			return RESPST_ERR_RKEY_VIOLATION;
		/* Make data persistent. */
		wmb();
	} else if (res->flush.type & IB_FLUSH_GLOBAL) {
		/* Make data global visibility. */
		wmb();
	}

	qp->resp.msn++;

	/* next expected psn, read handles this separately */
	qp->resp.psn = (pkt->psn + 1) & BTH_PSN_MASK;
	qp->resp.ack_psn = qp->resp.psn;

	qp->resp.opcode = pkt->opcode;
	qp->resp.status = IB_WC_SUCCESS;

	return RESPST_ACKNOWLEDGE;
}

static enum resp_states atomic_reply(struct rxe_qp *qp,
				     struct rxe_pkt_info *pkt)
{
	struct rxe_mr *mr = qp->resp.mr;
	struct resp_res *res = qp->resp.res;
	int err;

	if (!res) {
		res = rxe_prepare_res(qp, pkt, RXE_ATOMIC_MASK);
		qp->resp.res = res;
	}

	if (!res->replay) {
		u64 iova = qp->resp.va + qp->resp.offset;

		err = rxe_mr_do_atomic_op(mr, iova, pkt->opcode,
					  atmeth_comp(pkt),
					  atmeth_swap_add(pkt),
					  &res->atomic.orig_val);
		if (err)
			return err;

		qp->resp.msn++;

		/* next expected psn, read handles this separately */
		qp->resp.psn = (pkt->psn + 1) & BTH_PSN_MASK;
		qp->resp.ack_psn = qp->resp.psn;

		qp->resp.opcode = pkt->opcode;
		qp->resp.status = IB_WC_SUCCESS;
	}

	return RESPST_ACKNOWLEDGE;
}

static enum resp_states atomic_write_reply(struct rxe_qp *qp,
					   struct rxe_pkt_info *pkt)
{
	struct resp_res *res = qp->resp.res;
	struct rxe_mr *mr;
	u64 value;
	u64 iova;
	int err;

	if (!res) {
		res = rxe_prepare_res(qp, pkt, RXE_ATOMIC_WRITE_MASK);
		qp->resp.res = res;
	}

	if (res->replay)
		return RESPST_ACKNOWLEDGE;

	mr = qp->resp.mr;
	value = *(u64 *)payload_addr(pkt);
	iova = qp->resp.va + qp->resp.offset;

	err = rxe_mr_do_atomic_write(mr, iova, value);
	if (err)
		return err;

	qp->resp.resid = 0;
	qp->resp.msn++;

	/* next expected psn, read handles this separately */
	qp->resp.psn = (pkt->psn + 1) & BTH_PSN_MASK;
	qp->resp.ack_psn = qp->resp.psn;

	qp->resp.opcode = pkt->opcode;
	qp->resp.status = IB_WC_SUCCESS;

	return RESPST_ACKNOWLEDGE;
}

static struct sk_buff *prepare_ack_packet(struct rxe_qp *qp,
					  struct rxe_pkt_info *ack,
					  int opcode,
					  int payload,
					  u32 psn,
					  u8 syndrome)
{
	struct rxe_dev *rxe = to_rdev(qp->ibqp.device);
	struct sk_buff *skb;
	int paylen;
	int pad;
	int err;

	/*
	 * allocate packet
	 */
	pad = (-payload) & 0x3;
	paylen = rxe_opcode[opcode].length + payload + pad + RXE_ICRC_SIZE;

	skb = rxe_init_packet(rxe, &qp->pri_av, paylen, ack);
	if (!skb)
		return NULL;

	ack->qp = qp;
	ack->opcode = opcode;
	ack->mask = rxe_opcode[opcode].mask;
	ack->paylen = paylen;
	ack->psn = psn;

	bth_init(ack, opcode, 0, 0, pad, IB_DEFAULT_PKEY_FULL,
		 qp->attr.dest_qp_num, 0, psn);

	if (ack->mask & RXE_AETH_MASK) {
		aeth_set_syn(ack, syndrome);
		aeth_set_msn(ack, qp->resp.msn);
	}

	if (ack->mask & RXE_ATMACK_MASK)
		atmack_set_orig(ack, qp->resp.res->atomic.orig_val);

	err = rxe_prepare(&qp->pri_av, ack, skb);
	if (err) {
		kfree_skb(skb);
		return NULL;
	}

	return skb;
}

/**
 * rxe_recheck_mr - revalidate MR from rkey and get a reference
 * @qp: the qp
 * @rkey: the rkey
 *
 * This code allows the MR to be invalidated or deregistered or
 * the MW if one was used to be invalidated or deallocated.
 * It is assumed that the access permissions if originally good
 * are OK and the mappings to be unchanged.
 *
 * TODO: If someone reregisters an MR to change its size or
 * access permissions during the processing of an RDMA read
 * we should kill the responder resource and complete the
 * operation with an error.
 *
 * Return: mr on success else NULL
 */
static struct rxe_mr *rxe_recheck_mr(struct rxe_qp *qp, u32 rkey)
{
	struct rxe_dev *rxe = to_rdev(qp->ibqp.device);
	struct rxe_mr *mr;
	struct rxe_mw *mw;

	if (rkey_is_mw(rkey)) {
		mw = rxe_pool_get_index(&rxe->mw_pool, rkey >> 8);
		if (!mw)
			return NULL;

		mr = mw->mr;
		if (mw->rkey != rkey || mw->state != RXE_MW_STATE_VALID ||
		    !mr || mr->state != RXE_MR_STATE_VALID) {
			rxe_put(mw);
			return NULL;
		}

		rxe_get(mr);
		rxe_put(mw);

		return mr;
	}

	mr = rxe_pool_get_index(&rxe->mr_pool, rkey >> 8);
	if (!mr)
		return NULL;

	if (mr->rkey != rkey || mr->state != RXE_MR_STATE_VALID) {
		rxe_put(mr);
		return NULL;
	}

	return mr;
}

/* RDMA read response. If res is not NULL, then we have a current RDMA request
 * being processed or replayed.
 */
static enum resp_states read_reply(struct rxe_qp *qp,
				   struct rxe_pkt_info *req_pkt)
{
	struct rxe_pkt_info ack_pkt;
	struct sk_buff *skb;
	int mtu = qp->mtu;
	enum resp_states state;
	int payload;
	int opcode;
	int err;
	struct resp_res *res = qp->resp.res;
	struct rxe_mr *mr;

	if (!res) {
		res = rxe_prepare_res(qp, req_pkt, RXE_READ_MASK);
		qp->resp.res = res;
	}

	if (res->state == rdatm_res_state_new) {
		if (!res->replay || qp->resp.length == 0) {
			/* if length == 0 mr will be NULL (is ok)
			 * otherwise qp->resp.mr holds a ref on mr
			 * which we transfer to mr and drop below.
			 */
			mr = qp->resp.mr;
			qp->resp.mr = NULL;
		} else {
			mr = rxe_recheck_mr(qp, res->read.rkey);
			if (!mr)
				return RESPST_ERR_RKEY_VIOLATION;
		}

		if (res->read.resid <= mtu)
			opcode = IB_OPCODE_RC_RDMA_READ_RESPONSE_ONLY;
		else
			opcode = IB_OPCODE_RC_RDMA_READ_RESPONSE_FIRST;
	} else {
		/* re-lookup mr from rkey on all later packets.
		 * length will be non-zero. This can fail if someone
		 * modifies or destroys the mr since the first packet.
		 */
		mr = rxe_recheck_mr(qp, res->read.rkey);
		if (!mr)
			return RESPST_ERR_RKEY_VIOLATION;

		if (res->read.resid > mtu)
			opcode = IB_OPCODE_RC_RDMA_READ_RESPONSE_MIDDLE;
		else
			opcode = IB_OPCODE_RC_RDMA_READ_RESPONSE_LAST;
	}

	res->state = rdatm_res_state_next;

	payload = min_t(int, res->read.resid, mtu);

	skb = prepare_ack_packet(qp, &ack_pkt, opcode, payload,
				 res->cur_psn, AETH_ACK_UNLIMITED);
	if (!skb) {
		state = RESPST_ERR_RNR;
		goto err_out;
	}

	err = rxe_mr_copy(mr, res->read.va, payload_addr(&ack_pkt),
			  payload, RXE_FROM_MR_OBJ);
	if (err) {
		kfree_skb(skb);
		state = RESPST_ERR_RKEY_VIOLATION;
		goto err_out;
	}

	if (bth_pad(&ack_pkt)) {
		u8 *pad = payload_addr(&ack_pkt) + payload;

		memset(pad, 0, bth_pad(&ack_pkt));
	}

	/* rxe_xmit_packet always consumes the skb */
	err = rxe_xmit_packet(qp, &ack_pkt, skb);
	if (err) {
		state = RESPST_ERR_RNR;
		goto err_out;
	}

	res->read.va += payload;
	res->read.resid -= payload;
	res->cur_psn = (res->cur_psn + 1) & BTH_PSN_MASK;

	if (res->read.resid > 0) {
		state = RESPST_DONE;
	} else {
		qp->resp.res = NULL;
		if (!res->replay)
			qp->resp.opcode = -1;
		if (psn_compare(res->cur_psn, qp->resp.psn) >= 0)
			qp->resp.psn = res->cur_psn;
		state = RESPST_CLEANUP;
	}

err_out:
	if (mr)
		rxe_put(mr);
	return state;
}

static int invalidate_rkey(struct rxe_qp *qp, u32 rkey)
{
	if (rkey_is_mw(rkey))
		return rxe_invalidate_mw(qp, rkey);
	else
		return rxe_invalidate_mr(qp, rkey);
}

/* Executes a new request. A retried request never reach that function (send
 * and writes are discarded, and reads and atomics are retried elsewhere.
 */
static enum resp_states execute(struct rxe_qp *qp, struct rxe_pkt_info *pkt)
{
	enum resp_states err;
	struct sk_buff *skb = PKT_TO_SKB(pkt);
	union rdma_network_hdr hdr;

	if (pkt->mask & RXE_SEND_MASK) {
		if (qp_type(qp) == IB_QPT_UD ||
		    qp_type(qp) == IB_QPT_GSI) {
			if (skb->protocol == htons(ETH_P_IP)) {
				memset(&hdr.reserved, 0,
						sizeof(hdr.reserved));
				memcpy(&hdr.roce4grh, ip_hdr(skb),
						sizeof(hdr.roce4grh));
				err = send_data_in(qp, &hdr, sizeof(hdr));
			} else {
				err = send_data_in(qp, ipv6_hdr(skb),
						sizeof(hdr));
			}
			if (err)
				return err;
		}
		err = send_data_in(qp, payload_addr(pkt), payload_size(pkt));
		if (err)
			return err;
	} else if (pkt->mask & RXE_WRITE_MASK) {
		err = write_data_in(qp, pkt);
		if (err)
			return err;
	} else if (pkt->mask & RXE_READ_MASK) {
		/* For RDMA Read we can increment the msn now. See C9-148. */
		qp->resp.msn++;
		return RESPST_READ_REPLY;
	} else if (pkt->mask & RXE_ATOMIC_MASK) {
		return RESPST_ATOMIC_REPLY;
	} else if (pkt->mask & RXE_ATOMIC_WRITE_MASK) {
		return RESPST_ATOMIC_WRITE_REPLY;
	} else if (pkt->mask & RXE_FLUSH_MASK) {
		return RESPST_PROCESS_FLUSH;
	} else {
		/* Unreachable */
		WARN_ON_ONCE(1);
	}

	if (pkt->mask & RXE_IETH_MASK) {
		u32 rkey = ieth_rkey(pkt);

		err = invalidate_rkey(qp, rkey);
		if (err)
			return RESPST_ERR_INVALIDATE_RKEY;
	}

	if (pkt->mask & RXE_END_MASK)
		/* We successfully processed this new request. */
		qp->resp.msn++;

	/* next expected psn, read handles this separately */
	qp->resp.psn = (pkt->psn + 1) & BTH_PSN_MASK;
	qp->resp.ack_psn = qp->resp.psn;

	qp->resp.opcode = pkt->opcode;
	qp->resp.status = IB_WC_SUCCESS;

	if (pkt->mask & RXE_COMP_MASK)
		return RESPST_COMPLETE;
	else if (qp_type(qp) == IB_QPT_RC)
		return RESPST_ACKNOWLEDGE;
	else
		return RESPST_CLEANUP;
}

static enum resp_states do_complete(struct rxe_qp *qp,
				    struct rxe_pkt_info *pkt)
{
	struct rxe_cqe cqe;
	struct ib_wc *wc = &cqe.ibwc;
	struct ib_uverbs_wc *uwc = &cqe.uibwc;
	struct rxe_recv_wqe *wqe = qp->resp.wqe;
	struct rxe_dev *rxe = to_rdev(qp->ibqp.device);
	unsigned long flags;

	if (!wqe)
		goto finish;

	memset(&cqe, 0, sizeof(cqe));

	if (qp->rcq->is_user) {
		uwc->status		= qp->resp.status;
		uwc->qp_num		= qp->ibqp.qp_num;
		uwc->wr_id		= wqe->wr_id;
	} else {
		wc->status		= qp->resp.status;
		wc->qp			= &qp->ibqp;
		wc->wr_id		= wqe->wr_id;
	}

	if (wc->status == IB_WC_SUCCESS) {
		rxe_counter_inc(rxe, RXE_CNT_RDMA_RECV);
		wc->opcode = (pkt->mask & RXE_IMMDT_MASK &&
				pkt->mask & RXE_WRITE_MASK) ?
					IB_WC_RECV_RDMA_WITH_IMM : IB_WC_RECV;
		wc->byte_len = (pkt->mask & RXE_IMMDT_MASK &&
				pkt->mask & RXE_WRITE_MASK) ?
					qp->resp.length : wqe->dma.length - wqe->dma.resid;

		/* fields after byte_len are different between kernel and user
		 * space
		 */
		if (qp->rcq->is_user) {
			uwc->wc_flags = IB_WC_GRH;

			if (pkt->mask & RXE_IMMDT_MASK) {
				uwc->wc_flags |= IB_WC_WITH_IMM;
				uwc->ex.imm_data = immdt_imm(pkt);
			}

			if (pkt->mask & RXE_IETH_MASK) {
				uwc->wc_flags |= IB_WC_WITH_INVALIDATE;
				uwc->ex.invalidate_rkey = ieth_rkey(pkt);
			}

			if (pkt->mask & RXE_DETH_MASK)
				uwc->src_qp = deth_sqp(pkt);

			uwc->port_num		= qp->attr.port_num;
		} else {
			struct sk_buff *skb = PKT_TO_SKB(pkt);

			wc->wc_flags = IB_WC_GRH | IB_WC_WITH_NETWORK_HDR_TYPE;
			if (skb->protocol == htons(ETH_P_IP))
				wc->network_hdr_type = RDMA_NETWORK_IPV4;
			else
				wc->network_hdr_type = RDMA_NETWORK_IPV6;

			if (is_vlan_dev(skb->dev)) {
				wc->wc_flags |= IB_WC_WITH_VLAN;
				wc->vlan_id = vlan_dev_vlan_id(skb->dev);
			}

			if (pkt->mask & RXE_IMMDT_MASK) {
				wc->wc_flags |= IB_WC_WITH_IMM;
				wc->ex.imm_data = immdt_imm(pkt);
			}

			if (pkt->mask & RXE_IETH_MASK) {
				wc->wc_flags |= IB_WC_WITH_INVALIDATE;
				wc->ex.invalidate_rkey = ieth_rkey(pkt);
			}

			if (pkt->mask & RXE_DETH_MASK)
				wc->src_qp = deth_sqp(pkt);

			wc->port_num		= qp->attr.port_num;
		}
	} else {
		if (wc->status != IB_WC_WR_FLUSH_ERR)
			rxe_err_qp(qp, "non-flush error status = %d",
				wc->status);
	}

	/* have copy for srq and reference for !srq */
	if (!qp->srq)
		queue_advance_consumer(qp->rq.queue, QUEUE_TYPE_FROM_CLIENT);

	qp->resp.wqe = NULL;

	if (rxe_cq_post(qp->rcq, &cqe, pkt ? bth_se(pkt) : 1))
		return RESPST_ERR_CQ_OVERFLOW;

finish:
	spin_lock_irqsave(&qp->state_lock, flags);
	if (unlikely(qp_state(qp) == IB_QPS_ERR)) {
		spin_unlock_irqrestore(&qp->state_lock, flags);
		return RESPST_CHK_RESOURCE;
	}
	spin_unlock_irqrestore(&qp->state_lock, flags);

	if (unlikely(!pkt))
		return RESPST_DONE;
	if (qp_type(qp) == IB_QPT_RC)
		return RESPST_ACKNOWLEDGE;
	else
		return RESPST_CLEANUP;
}


static int send_common_ack(struct rxe_qp *qp, u8 syndrome, u32 psn,
				  int opcode, const char *msg)
{
	int err;
	struct rxe_pkt_info ack_pkt;
	struct sk_buff *skb;

	skb = prepare_ack_packet(qp, &ack_pkt, opcode, 0, psn, syndrome);
	if (!skb)
		return -ENOMEM;

	err = rxe_xmit_packet(qp, &ack_pkt, skb);
	if (err)
		rxe_dbg_qp(qp, "Failed sending %s\n", msg);

	return err;
}

static int send_ack(struct rxe_qp *qp, u8 syndrome, u32 psn)
{
	return send_common_ack(qp, syndrome, psn,
			IB_OPCODE_RC_ACKNOWLEDGE, "ACK");
}

static int send_atomic_ack(struct rxe_qp *qp, u8 syndrome, u32 psn)
{
	int ret = send_common_ack(qp, syndrome, psn,
			IB_OPCODE_RC_ATOMIC_ACKNOWLEDGE, "ATOMIC ACK");

	/* have to clear this since it is used to trigger
	 * long read replies
	 */
	qp->resp.res = NULL;
	return ret;
}

static int send_read_response_ack(struct rxe_qp *qp, u8 syndrome, u32 psn)
{
	int ret = send_common_ack(qp, syndrome, psn,
			IB_OPCODE_RC_RDMA_READ_RESPONSE_ONLY,
			"RDMA READ response of length zero ACK");

	/* have to clear this since it is used to trigger
	 * long read replies
	 */
	qp->resp.res = NULL;
	return ret;
}

static enum resp_states acknowledge(struct rxe_qp *qp,
				    struct rxe_pkt_info *pkt)
{
	if (qp_type(qp) != IB_QPT_RC)
		return RESPST_CLEANUP;

	if (qp->resp.aeth_syndrome != AETH_ACK_UNLIMITED)
		send_ack(qp, qp->resp.aeth_syndrome, pkt->psn);
	else if (pkt->mask & RXE_ATOMIC_MASK)
		send_atomic_ack(qp, AETH_ACK_UNLIMITED, pkt->psn);
	else if (pkt->mask & (RXE_FLUSH_MASK | RXE_ATOMIC_WRITE_MASK))
		send_read_response_ack(qp, AETH_ACK_UNLIMITED, pkt->psn);
	else if (bth_ack(pkt))
		send_ack(qp, AETH_ACK_UNLIMITED, pkt->psn);

	return RESPST_CLEANUP;
}

static enum resp_states cleanup(struct rxe_qp *qp,
				struct rxe_pkt_info *pkt)
{
	struct sk_buff *skb;

	if (pkt) {
		skb = skb_dequeue(&qp->req_pkts);
		rxe_put(qp);
		kfree_skb(skb);
		ib_device_put(qp->ibqp.device);
	}

	if (qp->resp.mr) {
		rxe_put(qp->resp.mr);
		qp->resp.mr = NULL;
	}

	return RESPST_DONE;
}

static struct resp_res *find_resource(struct rxe_qp *qp, u32 psn)
{
	int i;

	for (i = 0; i < qp->attr.max_dest_rd_atomic; i++) {
		struct resp_res *res = &qp->resp.resources[i];

		if (res->type == 0)
			continue;

		if (psn_compare(psn, res->first_psn) >= 0 &&
		    psn_compare(psn, res->last_psn) <= 0) {
			return res;
		}
	}

	return NULL;
}

static enum resp_states duplicate_request(struct rxe_qp *qp,
					  struct rxe_pkt_info *pkt)
{
	enum resp_states rc;
	u32 prev_psn = (qp->resp.ack_psn - 1) & BTH_PSN_MASK;

	if (pkt->mask & RXE_SEND_MASK ||
	    pkt->mask & RXE_WRITE_MASK) {
		/* SEND. Ack again and cleanup. C9-105. */
		send_ack(qp, AETH_ACK_UNLIMITED, prev_psn);
		return RESPST_CLEANUP;
	} else if (pkt->mask & RXE_FLUSH_MASK) {
		struct resp_res *res;

		/* Find the operation in our list of responder resources. */
		res = find_resource(qp, pkt->psn);
		if (res) {
			res->replay = 1;
			res->cur_psn = pkt->psn;
			qp->resp.res = res;
			rc = RESPST_PROCESS_FLUSH;
			goto out;
		}

		/* Resource not found. Class D error. Drop the request. */
		rc = RESPST_CLEANUP;
		goto out;
	} else if (pkt->mask & RXE_READ_MASK) {
		struct resp_res *res;

		res = find_resource(qp, pkt->psn);
		if (!res) {
			/* Resource not found. Class D error.  Drop the
			 * request.
			 */
			rc = RESPST_CLEANUP;
			goto out;
		} else {
			/* Ensure this new request is the same as the previous
			 * one or a subset of it.
			 */
			u64 iova = reth_va(pkt);
			u32 resid = reth_len(pkt);

			if (iova < res->read.va_org ||
			    resid > res->read.length ||
			    (iova + resid) > (res->read.va_org +
					      res->read.length)) {
				rc = RESPST_CLEANUP;
				goto out;
			}

			if (reth_rkey(pkt) != res->read.rkey) {
				rc = RESPST_CLEANUP;
				goto out;
			}

			res->cur_psn = pkt->psn;
			res->state = (pkt->psn == res->first_psn) ?
					rdatm_res_state_new :
					rdatm_res_state_replay;
			res->replay = 1;

			/* Reset the resource, except length. */
			res->read.va_org = iova;
			res->read.va = iova;
			res->read.resid = resid;

			/* Replay the RDMA read reply. */
			qp->resp.res = res;
			rc = RESPST_READ_REPLY;
			goto out;
		}
	} else {
		struct resp_res *res;

		/* Find the operation in our list of responder resources. */
		res = find_resource(qp, pkt->psn);
		if (res) {
			res->replay = 1;
			res->cur_psn = pkt->psn;
			qp->resp.res = res;
			rc = pkt->mask & RXE_ATOMIC_MASK ?
					RESPST_ATOMIC_REPLY :
					RESPST_ATOMIC_WRITE_REPLY;
			goto out;
		}

		/* Resource not found. Class D error. Drop the request. */
		rc = RESPST_CLEANUP;
		goto out;
	}
out:
	return rc;
}

/* Process a class A or C. Both are treated the same in this implementation. */
static void do_class_ac_error(struct rxe_qp *qp, u8 syndrome,
			      enum ib_wc_status status)
{
	qp->resp.aeth_syndrome	= syndrome;
	qp->resp.status		= status;

	/* indicate that we should go through the ERROR state */
	qp->resp.goto_error	= 1;
}

static enum resp_states do_class_d1e_error(struct rxe_qp *qp)
{
	/* UC */
	if (qp->srq) {
		/* Class E */
		qp->resp.drop_msg = 1;
		if (qp->resp.wqe) {
			qp->resp.status = IB_WC_REM_INV_REQ_ERR;
			return RESPST_COMPLETE;
		} else {
			return RESPST_CLEANUP;
		}
	} else {
		/* Class D1. This packet may be the start of a
		 * new message and could be valid. The previous
		 * message is invalid and ignored. reset the
		 * recv wr to its original state
		 */
		if (qp->resp.wqe) {
			qp->resp.wqe->dma.resid = qp->resp.wqe->dma.length;
			qp->resp.wqe->dma.cur_sge = 0;
			qp->resp.wqe->dma.sge_offset = 0;
			qp->resp.opcode = -1;
		}

		if (qp->resp.mr) {
			rxe_put(qp->resp.mr);
			qp->resp.mr = NULL;
		}

		return RESPST_CLEANUP;
	}
}

/* drain incoming request packet queue */
static void drain_req_pkts(struct rxe_qp *qp)
{
	struct sk_buff *skb;

	while ((skb = skb_dequeue(&qp->req_pkts))) {
		rxe_put(qp);
		kfree_skb(skb);
		ib_device_put(qp->ibqp.device);
	}
}

/* complete receive wqe with flush error */
static int flush_recv_wqe(struct rxe_qp *qp, struct rxe_recv_wqe *wqe)
{
	struct rxe_cqe cqe = {};
	struct ib_wc *wc = &cqe.ibwc;
	struct ib_uverbs_wc *uwc = &cqe.uibwc;
	int err;

	if (qp->rcq->is_user) {
		uwc->wr_id = wqe->wr_id;
		uwc->status = IB_WC_WR_FLUSH_ERR;
		uwc->qp_num = qp_num(qp);
	} else {
		wc->wr_id = wqe->wr_id;
		wc->status = IB_WC_WR_FLUSH_ERR;
		wc->qp = &qp->ibqp;
	}

	err = rxe_cq_post(qp->rcq, &cqe, 0);
	if (err)
		rxe_dbg_cq(qp->rcq, "post cq failed err = %d", err);

	return err;
}

/* drain and optionally complete the recive queue
 * if unable to complete a wqe stop completing and
 * just flush the remaining wqes
 */
static void flush_recv_queue(struct rxe_qp *qp, bool notify)
{
	struct rxe_queue *q = qp->rq.queue;
	struct rxe_recv_wqe *wqe;
	int err;

	if (qp->srq) {
		if (notify && qp->ibqp.event_handler) {
			struct ib_event ev;

			ev.device = qp->ibqp.device;
			ev.element.qp = &qp->ibqp;
			ev.event = IB_EVENT_QP_LAST_WQE_REACHED;
			qp->ibqp.event_handler(&ev, qp->ibqp.qp_context);
		}
		return;
	}

	/* recv queue not created. nothing to do. */
	if (!qp->rq.queue)
		return;

	while ((wqe = queue_head(q, q->type))) {
		if (notify) {
			err = flush_recv_wqe(qp, wqe);
			if (err)
				notify = 0;
		}
		queue_advance_consumer(q, q->type);
	}

	qp->resp.wqe = NULL;
}

int rxe_responder(struct rxe_qp *qp)
{
	struct rxe_dev *rxe = to_rdev(qp->ibqp.device);
	enum resp_states state;
	struct rxe_pkt_info *pkt = NULL;
	int ret;
	unsigned long flags;

	spin_lock_irqsave(&qp->state_lock, flags);
	if (!qp->valid || qp_state(qp) == IB_QPS_ERR ||
			  qp_state(qp) == IB_QPS_RESET) {
		bool notify = qp->valid && (qp_state(qp) == IB_QPS_ERR);

		drain_req_pkts(qp);
		flush_recv_queue(qp, notify);
		spin_unlock_irqrestore(&qp->state_lock, flags);
		goto exit;
	}
	spin_unlock_irqrestore(&qp->state_lock, flags);

	qp->resp.aeth_syndrome = AETH_ACK_UNLIMITED;

	state = RESPST_GET_REQ;

	while (1) {
		rxe_dbg_qp(qp, "state = %s\n", resp_state_name[state]);
		switch (state) {
		case RESPST_GET_REQ:
			state = get_req(qp, &pkt);
			break;
		case RESPST_CHK_PSN:
			state = check_psn(qp, pkt);
			break;
		case RESPST_CHK_OP_SEQ:
			state = check_op_seq(qp, pkt);
			break;
		case RESPST_CHK_OP_VALID:
			state = check_op_valid(qp, pkt);
			break;
		case RESPST_CHK_RESOURCE:
			state = check_resource(qp, pkt);
			break;
		case RESPST_CHK_LENGTH:
			state = rxe_resp_check_length(qp, pkt);
			break;
		case RESPST_CHK_RKEY:
			state = check_rkey(qp, pkt);
			break;
		case RESPST_EXECUTE:
			state = execute(qp, pkt);
			break;
		case RESPST_COMPLETE:
			state = do_complete(qp, pkt);
			break;
		case RESPST_READ_REPLY:
			state = read_reply(qp, pkt);
			break;
		case RESPST_ATOMIC_REPLY:
			state = atomic_reply(qp, pkt);
			break;
		case RESPST_ATOMIC_WRITE_REPLY:
			state = atomic_write_reply(qp, pkt);
			break;
		case RESPST_PROCESS_FLUSH:
			state = process_flush(qp, pkt);
			break;
		case RESPST_ACKNOWLEDGE:
			state = acknowledge(qp, pkt);
			break;
		case RESPST_CLEANUP:
			state = cleanup(qp, pkt);
			break;
		case RESPST_DUPLICATE_REQUEST:
			state = duplicate_request(qp, pkt);
			break;
		case RESPST_ERR_PSN_OUT_OF_SEQ:
			/* RC only - Class B. Drop packet. */
			send_ack(qp, AETH_NAK_PSN_SEQ_ERROR, qp->resp.psn);
			state = RESPST_CLEANUP;
			break;

		case RESPST_ERR_TOO_MANY_RDMA_ATM_REQ:
		case RESPST_ERR_MISSING_OPCODE_FIRST:
		case RESPST_ERR_MISSING_OPCODE_LAST_C:
		case RESPST_ERR_UNSUPPORTED_OPCODE:
		case RESPST_ERR_MISALIGNED_ATOMIC:
			/* RC Only - Class C. */
			do_class_ac_error(qp, AETH_NAK_INVALID_REQ,
					  IB_WC_REM_INV_REQ_ERR);
			state = RESPST_COMPLETE;
			break;

		case RESPST_ERR_MISSING_OPCODE_LAST_D1E:
			state = do_class_d1e_error(qp);
			break;
		case RESPST_ERR_RNR:
			if (qp_type(qp) == IB_QPT_RC) {
				rxe_counter_inc(rxe, RXE_CNT_SND_RNR);
				/* RC - class B */
				send_ack(qp, AETH_RNR_NAK |
					 (~AETH_TYPE_MASK &
					 qp->attr.min_rnr_timer),
					 pkt->psn);
			} else {
				/* UD/UC - class D */
				qp->resp.drop_msg = 1;
			}
			state = RESPST_CLEANUP;
			break;

		case RESPST_ERR_RKEY_VIOLATION:
			if (qp_type(qp) == IB_QPT_RC) {
				/* Class C */
				do_class_ac_error(qp, AETH_NAK_REM_ACC_ERR,
						  IB_WC_REM_ACCESS_ERR);
				state = RESPST_COMPLETE;
			} else {
				qp->resp.drop_msg = 1;
				if (qp->srq) {
					/* UC/SRQ Class D */
					qp->resp.status = IB_WC_REM_ACCESS_ERR;
					state = RESPST_COMPLETE;
				} else {
					/* UC/non-SRQ Class E. */
					state = RESPST_CLEANUP;
				}
			}
			break;

		case RESPST_ERR_INVALIDATE_RKEY:
			/* RC - Class J. */
			qp->resp.goto_error = 1;
			qp->resp.status = IB_WC_REM_INV_REQ_ERR;
			state = RESPST_COMPLETE;
			break;

		case RESPST_ERR_LENGTH:
			if (qp_type(qp) == IB_QPT_RC) {
				/* Class C */
				do_class_ac_error(qp, AETH_NAK_INVALID_REQ,
						  IB_WC_REM_INV_REQ_ERR);
				state = RESPST_COMPLETE;
			} else if (qp->srq) {
				/* UC/UD - class E */
				qp->resp.status = IB_WC_REM_INV_REQ_ERR;
				state = RESPST_COMPLETE;
			} else {
				/* UC/UD - class D */
				qp->resp.drop_msg = 1;
				state = RESPST_CLEANUP;
			}
			break;

		case RESPST_ERR_MALFORMED_WQE:
			/* All, Class A. */
			do_class_ac_error(qp, AETH_NAK_REM_OP_ERR,
					  IB_WC_LOC_QP_OP_ERR);
			state = RESPST_COMPLETE;
			break;

		case RESPST_ERR_CQ_OVERFLOW:
			/* All - Class G */
			state = RESPST_ERROR;
			break;

		case RESPST_DONE:
			if (qp->resp.goto_error) {
				state = RESPST_ERROR;
				break;
			}

			goto done;

		case RESPST_EXIT:
			if (qp->resp.goto_error) {
				state = RESPST_ERROR;
				break;
			}

			goto exit;

		case RESPST_ERROR:
			qp->resp.goto_error = 0;
			rxe_dbg_qp(qp, "moved to error state\n");
			rxe_qp_error(qp);
			goto exit;

		default:
			WARN_ON_ONCE(1);
		}
	}

	/* A non-zero return value will cause rxe_do_task to
	 * exit its loop and end the work item. A zero return
	 * will continue looping and return to rxe_responder
	 */
done:
	ret = 0;
	goto out;
exit:
	ret = -EAGAIN;
out:
	return ret;
}