1 files changed, 851 insertions, 0 deletions

diff --git a/drivers/infiniband/sw/rxe/rxe_comp.c b/drivers/infiniband/sw/rxe/rxe_comp.c
new file mode 100644
index 0000000000..d0bdc2d8ad
--- /dev/null
+++ b/drivers/infiniband/sw/rxe/rxe_comp.c
@@ -0,0 +1,851 @@
+// 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"
+#include "rxe_task.h"
+
+enum comp_state {
+	COMPST_GET_ACK,
+	COMPST_GET_WQE,
+	COMPST_COMP_WQE,
+	COMPST_COMP_ACK,
+	COMPST_CHECK_PSN,
+	COMPST_CHECK_ACK,
+	COMPST_READ,
+	COMPST_ATOMIC,
+	COMPST_WRITE_SEND,
+	COMPST_UPDATE_COMP,
+	COMPST_ERROR_RETRY,
+	COMPST_RNR_RETRY,
+	COMPST_ERROR,
+	COMPST_EXIT, /* We have an issue, and we want to rerun the completer */
+	COMPST_DONE, /* The completer finished successflly */
+};
+
+static char *comp_state_name[] =  {
+	[COMPST_GET_ACK]		= "GET ACK",
+	[COMPST_GET_WQE]		= "GET WQE",
+	[COMPST_COMP_WQE]		= "COMP WQE",
+	[COMPST_COMP_ACK]		= "COMP ACK",
+	[COMPST_CHECK_PSN]		= "CHECK PSN",
+	[COMPST_CHECK_ACK]		= "CHECK ACK",
+	[COMPST_READ]			= "READ",
+	[COMPST_ATOMIC]			= "ATOMIC",
+	[COMPST_WRITE_SEND]		= "WRITE/SEND",
+	[COMPST_UPDATE_COMP]		= "UPDATE COMP",
+	[COMPST_ERROR_RETRY]		= "ERROR RETRY",
+	[COMPST_RNR_RETRY]		= "RNR RETRY",
+	[COMPST_ERROR]			= "ERROR",
+	[COMPST_EXIT]			= "EXIT",
+	[COMPST_DONE]			= "DONE",
+};
+
+static unsigned long rnrnak_usec[32] = {
+	[IB_RNR_TIMER_655_36] = 655360,
+	[IB_RNR_TIMER_000_01] = 10,
+	[IB_RNR_TIMER_000_02] = 20,
+	[IB_RNR_TIMER_000_03] = 30,
+	[IB_RNR_TIMER_000_04] = 40,
+	[IB_RNR_TIMER_000_06] = 60,
+	[IB_RNR_TIMER_000_08] = 80,
+	[IB_RNR_TIMER_000_12] = 120,
+	[IB_RNR_TIMER_000_16] = 160,
+	[IB_RNR_TIMER_000_24] = 240,
+	[IB_RNR_TIMER_000_32] = 320,
+	[IB_RNR_TIMER_000_48] = 480,
+	[IB_RNR_TIMER_000_64] = 640,
+	[IB_RNR_TIMER_000_96] = 960,
+	[IB_RNR_TIMER_001_28] = 1280,
+	[IB_RNR_TIMER_001_92] = 1920,
+	[IB_RNR_TIMER_002_56] = 2560,
+	[IB_RNR_TIMER_003_84] = 3840,
+	[IB_RNR_TIMER_005_12] = 5120,
+	[IB_RNR_TIMER_007_68] = 7680,
+	[IB_RNR_TIMER_010_24] = 10240,
+	[IB_RNR_TIMER_015_36] = 15360,
+	[IB_RNR_TIMER_020_48] = 20480,
+	[IB_RNR_TIMER_030_72] = 30720,
+	[IB_RNR_TIMER_040_96] = 40960,
+	[IB_RNR_TIMER_061_44] = 61410,
+	[IB_RNR_TIMER_081_92] = 81920,
+	[IB_RNR_TIMER_122_88] = 122880,
+	[IB_RNR_TIMER_163_84] = 163840,
+	[IB_RNR_TIMER_245_76] = 245760,
+	[IB_RNR_TIMER_327_68] = 327680,
+	[IB_RNR_TIMER_491_52] = 491520,
+};
+
+static inline unsigned long rnrnak_jiffies(u8 timeout)
+{
+	return max_t(unsigned long,
+		usecs_to_jiffies(rnrnak_usec[timeout]), 1);
+}
+
+static enum ib_wc_opcode wr_to_wc_opcode(enum ib_wr_opcode opcode)
+{
+	switch (opcode) {
+	case IB_WR_RDMA_WRITE:			return IB_WC_RDMA_WRITE;
+	case IB_WR_RDMA_WRITE_WITH_IMM:		return IB_WC_RDMA_WRITE;
+	case IB_WR_SEND:			return IB_WC_SEND;
+	case IB_WR_SEND_WITH_IMM:		return IB_WC_SEND;
+	case IB_WR_RDMA_READ:			return IB_WC_RDMA_READ;
+	case IB_WR_ATOMIC_CMP_AND_SWP:		return IB_WC_COMP_SWAP;
+	case IB_WR_ATOMIC_FETCH_AND_ADD:	return IB_WC_FETCH_ADD;
+	case IB_WR_LSO:				return IB_WC_LSO;
+	case IB_WR_SEND_WITH_INV:		return IB_WC_SEND;
+	case IB_WR_RDMA_READ_WITH_INV:		return IB_WC_RDMA_READ;
+	case IB_WR_LOCAL_INV:			return IB_WC_LOCAL_INV;
+	case IB_WR_REG_MR:			return IB_WC_REG_MR;
+	case IB_WR_BIND_MW:			return IB_WC_BIND_MW;
+	case IB_WR_ATOMIC_WRITE:		return IB_WC_ATOMIC_WRITE;
+	case IB_WR_FLUSH:			return IB_WC_FLUSH;
+
+	default:
+		return 0xff;
+	}
+}
+
+void retransmit_timer(struct timer_list *t)
+{
+	struct rxe_qp *qp = from_timer(qp, t, retrans_timer);
+	unsigned long flags;
+
+	rxe_dbg_qp(qp, "retransmit timer fired\n");
+
+	spin_lock_irqsave(&qp->state_lock, flags);
+	if (qp->valid) {
+		qp->comp.timeout = 1;
+		rxe_sched_task(&qp->comp.task);
+	}
+	spin_unlock_irqrestore(&qp->state_lock, flags);
+}
+
+void rxe_comp_queue_pkt(struct rxe_qp *qp, struct sk_buff *skb)
+{
+	int must_sched;
+
+	skb_queue_tail(&qp->resp_pkts, skb);
+
+	must_sched = skb_queue_len(&qp->resp_pkts) > 1;
+	if (must_sched != 0)
+		rxe_counter_inc(SKB_TO_PKT(skb)->rxe, RXE_CNT_COMPLETER_SCHED);
+
+	if (must_sched)
+		rxe_sched_task(&qp->comp.task);
+	else
+		rxe_run_task(&qp->comp.task);
+}
+
+static inline enum comp_state get_wqe(struct rxe_qp *qp,
+				      struct rxe_pkt_info *pkt,
+				      struct rxe_send_wqe **wqe_p)
+{
+	struct rxe_send_wqe *wqe;
+
+	/* we come here whether or not we found a response packet to see if
+	 * there are any posted WQEs
+	 */
+	wqe = queue_head(qp->sq.queue, QUEUE_TYPE_FROM_CLIENT);
+	*wqe_p = wqe;
+
+	/* no WQE or requester has not started it yet */
+	if (!wqe || wqe->state == wqe_state_posted)
+		return pkt ? COMPST_DONE : COMPST_EXIT;
+
+	/* WQE does not require an ack */
+	if (wqe->state == wqe_state_done)
+		return COMPST_COMP_WQE;
+
+	/* WQE caused an error */
+	if (wqe->state == wqe_state_error)
+		return COMPST_ERROR;
+
+	/* we have a WQE, if we also have an ack check its PSN */
+	return pkt ? COMPST_CHECK_PSN : COMPST_EXIT;
+}
+
+static inline void reset_retry_counters(struct rxe_qp *qp)
+{
+	qp->comp.retry_cnt = qp->attr.retry_cnt;
+	qp->comp.rnr_retry = qp->attr.rnr_retry;
+	qp->comp.started_retry = 0;
+}
+
+static inline enum comp_state check_psn(struct rxe_qp *qp,
+					struct rxe_pkt_info *pkt,
+					struct rxe_send_wqe *wqe)
+{
+	s32 diff;
+
+	/* check to see if response is past the oldest WQE. if it is, complete
+	 * send/write or error read/atomic
+	 */
+	diff = psn_compare(pkt->psn, wqe->last_psn);
+	if (diff > 0) {
+		if (wqe->state == wqe_state_pending) {
+			if (wqe->mask & WR_ATOMIC_OR_READ_MASK)
+				return COMPST_ERROR_RETRY;
+
+			reset_retry_counters(qp);
+			return COMPST_COMP_WQE;
+		} else {
+			return COMPST_DONE;
+		}
+	}
+
+	/* compare response packet to expected response */
+	diff = psn_compare(pkt->psn, qp->comp.psn);
+	if (diff < 0) {
+		/* response is most likely a retried packet if it matches an
+		 * uncompleted WQE go complete it else ignore it
+		 */
+		if (pkt->psn == wqe->last_psn)
+			return COMPST_COMP_ACK;
+		else if (pkt->opcode == IB_OPCODE_RC_ACKNOWLEDGE &&
+			 (qp->comp.opcode == IB_OPCODE_RC_RDMA_READ_RESPONSE_FIRST ||
+			  qp->comp.opcode == IB_OPCODE_RC_RDMA_READ_RESPONSE_MIDDLE))
+			return COMPST_CHECK_ACK;
+		else
+			return COMPST_DONE;
+	} else if ((diff > 0) && (wqe->mask & WR_ATOMIC_OR_READ_MASK)) {
+		return COMPST_DONE;
+	} else {
+		return COMPST_CHECK_ACK;
+	}
+}
+
+static inline enum comp_state check_ack(struct rxe_qp *qp,
+					struct rxe_pkt_info *pkt,
+					struct rxe_send_wqe *wqe)
+{
+	unsigned int mask = pkt->mask;
+	u8 syn;
+	struct rxe_dev *rxe = to_rdev(qp->ibqp.device);
+
+	/* Check the sequence only */
+	switch (qp->comp.opcode) {
+	case -1:
+		/* Will catch all *_ONLY cases. */
+		if (!(mask & RXE_START_MASK))
+			return COMPST_ERROR;
+
+		break;
+
+	case IB_OPCODE_RC_RDMA_READ_RESPONSE_FIRST:
+	case IB_OPCODE_RC_RDMA_READ_RESPONSE_MIDDLE:
+		/* Check NAK code to handle a remote error */
+		if (pkt->opcode == IB_OPCODE_RC_ACKNOWLEDGE)
+			break;
+
+		if (pkt->opcode != IB_OPCODE_RC_RDMA_READ_RESPONSE_MIDDLE &&
+		    pkt->opcode != IB_OPCODE_RC_RDMA_READ_RESPONSE_LAST) {
+			/* read retries of partial data may restart from
+			 * read response first or response only.
+			 */
+			if ((pkt->psn == wqe->first_psn &&
+			     pkt->opcode ==
+			     IB_OPCODE_RC_RDMA_READ_RESPONSE_FIRST) ||
+			    (wqe->first_psn == wqe->last_psn &&
+			     pkt->opcode ==
+			     IB_OPCODE_RC_RDMA_READ_RESPONSE_ONLY))
+				break;
+
+			return COMPST_ERROR;
+		}
+		break;
+	default:
+		WARN_ON_ONCE(1);
+	}
+
+	/* Check operation validity. */
+	switch (pkt->opcode) {
+	case IB_OPCODE_RC_RDMA_READ_RESPONSE_FIRST:
+	case IB_OPCODE_RC_RDMA_READ_RESPONSE_LAST:
+	case IB_OPCODE_RC_RDMA_READ_RESPONSE_ONLY:
+		syn = aeth_syn(pkt);
+
+		if ((syn & AETH_TYPE_MASK) != AETH_ACK)
+			return COMPST_ERROR;
+
+		if (wqe->wr.opcode == IB_WR_ATOMIC_WRITE)
+			return COMPST_WRITE_SEND;
+
+		fallthrough;
+		/* (IB_OPCODE_RC_RDMA_READ_RESPONSE_MIDDLE doesn't have an AETH)
+		 */
+	case IB_OPCODE_RC_RDMA_READ_RESPONSE_MIDDLE:
+		if (wqe->wr.opcode != IB_WR_RDMA_READ &&
+		    wqe->wr.opcode != IB_WR_RDMA_READ_WITH_INV &&
+		    wqe->wr.opcode != IB_WR_FLUSH) {
+			wqe->status = IB_WC_FATAL_ERR;
+			return COMPST_ERROR;
+		}
+		reset_retry_counters(qp);
+		return COMPST_READ;
+
+	case IB_OPCODE_RC_ATOMIC_ACKNOWLEDGE:
+		syn = aeth_syn(pkt);
+
+		if ((syn & AETH_TYPE_MASK) != AETH_ACK)
+			return COMPST_ERROR;
+
+		if (wqe->wr.opcode != IB_WR_ATOMIC_CMP_AND_SWP &&
+		    wqe->wr.opcode != IB_WR_ATOMIC_FETCH_AND_ADD)
+			return COMPST_ERROR;
+		reset_retry_counters(qp);
+		return COMPST_ATOMIC;
+
+	case IB_OPCODE_RC_ACKNOWLEDGE:
+		syn = aeth_syn(pkt);
+		switch (syn & AETH_TYPE_MASK) {
+		case AETH_ACK:
+			reset_retry_counters(qp);
+			return COMPST_WRITE_SEND;
+
+		case AETH_RNR_NAK:
+			rxe_counter_inc(rxe, RXE_CNT_RCV_RNR);
+			return COMPST_RNR_RETRY;
+
+		case AETH_NAK:
+			switch (syn) {
+			case AETH_NAK_PSN_SEQ_ERROR:
+				/* a nak implicitly acks all packets with psns
+				 * before
+				 */
+				if (psn_compare(pkt->psn, qp->comp.psn) > 0) {
+					rxe_counter_inc(rxe,
+							RXE_CNT_RCV_SEQ_ERR);
+					qp->comp.psn = pkt->psn;
+					if (qp->req.wait_psn) {
+						qp->req.wait_psn = 0;
+						rxe_sched_task(&qp->req.task);
+					}
+				}
+				return COMPST_ERROR_RETRY;
+
+			case AETH_NAK_INVALID_REQ:
+				wqe->status = IB_WC_REM_INV_REQ_ERR;
+				return COMPST_ERROR;
+
+			case AETH_NAK_REM_ACC_ERR:
+				wqe->status = IB_WC_REM_ACCESS_ERR;
+				return COMPST_ERROR;
+
+			case AETH_NAK_REM_OP_ERR:
+				wqe->status = IB_WC_REM_OP_ERR;
+				return COMPST_ERROR;
+
+			default:
+				rxe_dbg_qp(qp, "unexpected nak %x\n", syn);
+				wqe->status = IB_WC_REM_OP_ERR;
+				return COMPST_ERROR;
+			}
+
+		default:
+			return COMPST_ERROR;
+		}
+		break;
+
+	default:
+		rxe_dbg_qp(qp, "unexpected opcode\n");
+	}
+
+	return COMPST_ERROR;
+}
+
+static inline enum comp_state do_read(struct rxe_qp *qp,
+				      struct rxe_pkt_info *pkt,
+				      struct rxe_send_wqe *wqe)
+{
+	int ret;
+
+	ret = copy_data(qp->pd, IB_ACCESS_LOCAL_WRITE,
+			&wqe->dma, payload_addr(pkt),
+			payload_size(pkt), RXE_TO_MR_OBJ);
+	if (ret) {
+		wqe->status = IB_WC_LOC_PROT_ERR;
+		return COMPST_ERROR;
+	}
+
+	if (wqe->dma.resid == 0 && (pkt->mask & RXE_END_MASK))
+		return COMPST_COMP_ACK;
+
+	return COMPST_UPDATE_COMP;
+}
+
+static inline enum comp_state do_atomic(struct rxe_qp *qp,
+					struct rxe_pkt_info *pkt,
+					struct rxe_send_wqe *wqe)
+{
+	int ret;
+
+	u64 atomic_orig = atmack_orig(pkt);
+
+	ret = copy_data(qp->pd, IB_ACCESS_LOCAL_WRITE,
+			&wqe->dma, &atomic_orig,
+			sizeof(u64), RXE_TO_MR_OBJ);
+	if (ret) {
+		wqe->status = IB_WC_LOC_PROT_ERR;
+		return COMPST_ERROR;
+	}
+
+	return COMPST_COMP_ACK;
+}
+
+static void make_send_cqe(struct rxe_qp *qp, struct rxe_send_wqe *wqe,
+			  struct rxe_cqe *cqe)
+{
+	struct ib_wc *wc = &cqe->ibwc;
+	struct ib_uverbs_wc *uwc = &cqe->uibwc;
+
+	memset(cqe, 0, sizeof(*cqe));
+
+	if (!qp->is_user) {
+		wc->wr_id = wqe->wr.wr_id;
+		wc->status = wqe->status;
+		wc->qp = &qp->ibqp;
+	} else {
+		uwc->wr_id = wqe->wr.wr_id;
+		uwc->status = wqe->status;
+		uwc->qp_num = qp->ibqp.qp_num;
+	}
+
+	if (wqe->status == IB_WC_SUCCESS) {
+		if (!qp->is_user) {
+			wc->opcode = wr_to_wc_opcode(wqe->wr.opcode);
+			if (wqe->wr.opcode == IB_WR_RDMA_WRITE_WITH_IMM ||
+			    wqe->wr.opcode == IB_WR_SEND_WITH_IMM)
+				wc->wc_flags = IB_WC_WITH_IMM;
+			wc->byte_len = wqe->dma.length;
+		} else {
+			uwc->opcode = wr_to_wc_opcode(wqe->wr.opcode);
+			if (wqe->wr.opcode == IB_WR_RDMA_WRITE_WITH_IMM ||
+			    wqe->wr.opcode == IB_WR_SEND_WITH_IMM)
+				uwc->wc_flags = IB_WC_WITH_IMM;
+			uwc->byte_len = wqe->dma.length;
+		}
+	} else {
+		if (wqe->status != IB_WC_WR_FLUSH_ERR)
+			rxe_err_qp(qp, "non-flush error status = %d",
+				wqe->status);
+	}
+}
+
+/*
+ * IBA Spec. Section 10.7.3.1 SIGNALED COMPLETIONS
+ * ---------8<---------8<-------------
+ * ...Note that if a completion error occurs, a Work Completion
+ * will always be generated, even if the signaling
+ * indicator requests an Unsignaled Completion.
+ * ---------8<---------8<-------------
+ */
+static void do_complete(struct rxe_qp *qp, struct rxe_send_wqe *wqe)
+{
+	struct rxe_dev *rxe = to_rdev(qp->ibqp.device);
+	struct rxe_cqe cqe;
+	bool post;
+
+	/* do we need to post a completion */
+	post = ((qp->sq_sig_type == IB_SIGNAL_ALL_WR) ||
+			(wqe->wr.send_flags & IB_SEND_SIGNALED) ||
+			wqe->status != IB_WC_SUCCESS);
+
+	if (post)
+		make_send_cqe(qp, wqe, &cqe);
+
+	queue_advance_consumer(qp->sq.queue, QUEUE_TYPE_FROM_CLIENT);
+
+	if (post)
+		rxe_cq_post(qp->scq, &cqe, 0);
+
+	if (wqe->wr.opcode == IB_WR_SEND ||
+	    wqe->wr.opcode == IB_WR_SEND_WITH_IMM ||
+	    wqe->wr.opcode == IB_WR_SEND_WITH_INV)
+		rxe_counter_inc(rxe, RXE_CNT_RDMA_SEND);
+
+	/*
+	 * we completed something so let req run again
+	 * if it is trying to fence
+	 */
+	if (qp->req.wait_fence) {
+		qp->req.wait_fence = 0;
+		rxe_sched_task(&qp->req.task);
+	}
+}
+
+static void comp_check_sq_drain_done(struct rxe_qp *qp)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&qp->state_lock, flags);
+	if (unlikely(qp_state(qp) == IB_QPS_SQD)) {
+		if (qp->attr.sq_draining && qp->comp.psn == qp->req.psn) {
+			qp->attr.sq_draining = 0;
+			spin_unlock_irqrestore(&qp->state_lock, flags);
+
+			if (qp->ibqp.event_handler) {
+				struct ib_event ev;
+
+				ev.device = qp->ibqp.device;
+				ev.element.qp = &qp->ibqp;
+				ev.event = IB_EVENT_SQ_DRAINED;
+				qp->ibqp.event_handler(&ev,
+					qp->ibqp.qp_context);
+			}
+			return;
+		}
+	}
+	spin_unlock_irqrestore(&qp->state_lock, flags);
+}
+
+static inline enum comp_state complete_ack(struct rxe_qp *qp,
+					   struct rxe_pkt_info *pkt,
+					   struct rxe_send_wqe *wqe)
+{
+	if (wqe->has_rd_atomic) {
+		wqe->has_rd_atomic = 0;
+		atomic_inc(&qp->req.rd_atomic);
+		if (qp->req.need_rd_atomic) {
+			qp->comp.timeout_retry = 0;
+			qp->req.need_rd_atomic = 0;
+			rxe_sched_task(&qp->req.task);
+		}
+	}
+
+	comp_check_sq_drain_done(qp);
+
+	do_complete(qp, wqe);
+
+	if (psn_compare(pkt->psn, qp->comp.psn) >= 0)
+		return COMPST_UPDATE_COMP;
+	else
+		return COMPST_DONE;
+}
+
+static inline enum comp_state complete_wqe(struct rxe_qp *qp,
+					   struct rxe_pkt_info *pkt,
+					   struct rxe_send_wqe *wqe)
+{
+	if (pkt && wqe->state == wqe_state_pending) {
+		if (psn_compare(wqe->last_psn, qp->comp.psn) >= 0) {
+			qp->comp.psn = (wqe->last_psn + 1) & BTH_PSN_MASK;
+			qp->comp.opcode = -1;
+		}
+
+		if (qp->req.wait_psn) {
+			qp->req.wait_psn = 0;
+			rxe_sched_task(&qp->req.task);
+		}
+	}
+
+	do_complete(qp, wqe);
+
+	return COMPST_GET_WQE;
+}
+
+/* drain incoming response packet queue */
+static void drain_resp_pkts(struct rxe_qp *qp)
+{
+	struct sk_buff *skb;
+
+	while ((skb = skb_dequeue(&qp->resp_pkts))) {
+		rxe_put(qp);
+		kfree_skb(skb);
+		ib_device_put(qp->ibqp.device);
+	}
+}
+
+/* complete send wqe with flush error */
+static int flush_send_wqe(struct rxe_qp *qp, struct rxe_send_wqe *wqe)
+{
+	struct rxe_cqe cqe = {};
+	struct ib_wc *wc = &cqe.ibwc;
+	struct ib_uverbs_wc *uwc = &cqe.uibwc;
+	int err;
+
+	if (qp->is_user) {
+		uwc->wr_id = wqe->wr.wr_id;
+		uwc->status = IB_WC_WR_FLUSH_ERR;
+		uwc->qp_num = qp->ibqp.qp_num;
+	} else {
+		wc->wr_id = wqe->wr.wr_id;
+		wc->status = IB_WC_WR_FLUSH_ERR;
+		wc->qp = &qp->ibqp;
+	}
+
+	err = rxe_cq_post(qp->scq, &cqe, 0);
+	if (err)
+		rxe_dbg_cq(qp->scq, "post cq failed, err = %d", err);
+
+	return err;
+}
+
+/* drain and optionally complete the send queue
+ * if unable to complete a wqe, i.e. cq is full, stop
+ * completing and flush the remaining wqes
+ */
+static void flush_send_queue(struct rxe_qp *qp, bool notify)
+{
+	struct rxe_send_wqe *wqe;
+	struct rxe_queue *q = qp->sq.queue;
+	int err;
+
+	/* send queue never got created. nothing to do. */
+	if (!qp->sq.queue)
+		return;
+
+	while ((wqe = queue_head(q, q->type))) {
+		if (notify) {
+			err = flush_send_wqe(qp, wqe);
+			if (err)
+				notify = 0;
+		}
+		queue_advance_consumer(q, q->type);
+	}
+}
+
+static void free_pkt(struct rxe_pkt_info *pkt)
+{
+	struct sk_buff *skb = PKT_TO_SKB(pkt);
+	struct rxe_qp *qp = pkt->qp;
+	struct ib_device *dev = qp->ibqp.device;
+
+	kfree_skb(skb);
+	rxe_put(qp);
+	ib_device_put(dev);
+}
+
+/* reset the retry timer if
+ * - QP is type RC
+ * - there is a packet sent by the requester that
+ *   might be acked (we still might get spurious
+ *   timeouts but try to keep them as few as possible)
+ * - the timeout parameter is set
+ * - the QP is alive
+ */
+static void reset_retry_timer(struct rxe_qp *qp)
+{
+	unsigned long flags;
+
+	if (qp_type(qp) == IB_QPT_RC && qp->qp_timeout_jiffies) {
+		spin_lock_irqsave(&qp->state_lock, flags);
+		if (qp_state(qp) >= IB_QPS_RTS &&
+		    psn_compare(qp->req.psn, qp->comp.psn) > 0)
+			mod_timer(&qp->retrans_timer,
+				  jiffies + qp->qp_timeout_jiffies);
+		spin_unlock_irqrestore(&qp->state_lock, flags);
+	}
+}
+
+int rxe_completer(struct rxe_qp *qp)
+{
+	struct rxe_dev *rxe = to_rdev(qp->ibqp.device);
+	struct rxe_send_wqe *wqe = NULL;
+	struct sk_buff *skb = NULL;
+	struct rxe_pkt_info *pkt = NULL;
+	enum comp_state state;
+	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_resp_pkts(qp);
+		flush_send_queue(qp, notify);
+		spin_unlock_irqrestore(&qp->state_lock, flags);
+		goto exit;
+	}
+	spin_unlock_irqrestore(&qp->state_lock, flags);
+
+	if (qp->comp.timeout) {
+		qp->comp.timeout_retry = 1;
+		qp->comp.timeout = 0;
+	} else {
+		qp->comp.timeout_retry = 0;
+	}
+
+	if (qp->req.need_retry)
+		goto exit;
+
+	state = COMPST_GET_ACK;
+
+	while (1) {
+		rxe_dbg_qp(qp, "state = %s\n", comp_state_name[state]);
+		switch (state) {
+		case COMPST_GET_ACK:
+			skb = skb_dequeue(&qp->resp_pkts);
+			if (skb) {
+				pkt = SKB_TO_PKT(skb);
+				qp->comp.timeout_retry = 0;
+			}
+			state = COMPST_GET_WQE;
+			break;
+
+		case COMPST_GET_WQE:
+			state = get_wqe(qp, pkt, &wqe);
+			break;
+
+		case COMPST_CHECK_PSN:
+			state = check_psn(qp, pkt, wqe);
+			break;
+
+		case COMPST_CHECK_ACK:
+			state = check_ack(qp, pkt, wqe);
+			break;
+
+		case COMPST_READ:
+			state = do_read(qp, pkt, wqe);
+			break;
+
+		case COMPST_ATOMIC:
+			state = do_atomic(qp, pkt, wqe);
+			break;
+
+		case COMPST_WRITE_SEND:
+			if (wqe->state == wqe_state_pending &&
+			    wqe->last_psn == pkt->psn)
+				state = COMPST_COMP_ACK;
+			else
+				state = COMPST_UPDATE_COMP;
+			break;
+
+		case COMPST_COMP_ACK:
+			state = complete_ack(qp, pkt, wqe);
+			break;
+
+		case COMPST_COMP_WQE:
+			state = complete_wqe(qp, pkt, wqe);
+			break;
+
+		case COMPST_UPDATE_COMP:
+			if (pkt->mask & RXE_END_MASK)
+				qp->comp.opcode = -1;
+			else
+				qp->comp.opcode = pkt->opcode;
+
+			if (psn_compare(pkt->psn, qp->comp.psn) >= 0)
+				qp->comp.psn = (pkt->psn + 1) & BTH_PSN_MASK;
+
+			if (qp->req.wait_psn) {
+				qp->req.wait_psn = 0;
+				rxe_sched_task(&qp->req.task);
+			}
+
+			state = COMPST_DONE;
+			break;
+
+		case COMPST_DONE:
+			goto done;
+
+		case COMPST_EXIT:
+			if (qp->comp.timeout_retry && wqe) {
+				state = COMPST_ERROR_RETRY;
+				break;
+			}
+
+			reset_retry_timer(qp);
+			goto exit;
+
+		case COMPST_ERROR_RETRY:
+			/* we come here if the retry timer fired and we did
+			 * not receive a response packet. try to retry the send
+			 * queue if that makes sense and the limits have not
+			 * been exceeded. remember that some timeouts are
+			 * spurious since we do not reset the timer but kick
+			 * it down the road or let it expire
+			 */
+
+			/* there is nothing to retry in this case */
+			if (!wqe || (wqe->state == wqe_state_posted))
+				goto exit;
+
+			/* if we've started a retry, don't start another
+			 * retry sequence, unless this is a timeout.
+			 */
+			if (qp->comp.started_retry &&
+			    !qp->comp.timeout_retry)
+				goto done;
+
+			if (qp->comp.retry_cnt > 0) {
+				if (qp->comp.retry_cnt != 7)
+					qp->comp.retry_cnt--;
+
+				/* no point in retrying if we have already
+				 * seen the last ack that the requester could
+				 * have caused
+				 */
+				if (psn_compare(qp->req.psn,
+						qp->comp.psn) > 0) {
+					/* tell the requester to retry the
+					 * send queue next time around
+					 */
+					rxe_counter_inc(rxe,
+							RXE_CNT_COMP_RETRY);
+					qp->req.need_retry = 1;
+					qp->comp.started_retry = 1;
+					rxe_sched_task(&qp->req.task);
+				}
+				goto done;
+
+			} else {
+				rxe_counter_inc(rxe, RXE_CNT_RETRY_EXCEEDED);
+				wqe->status = IB_WC_RETRY_EXC_ERR;
+				state = COMPST_ERROR;
+			}
+			break;
+
+		case COMPST_RNR_RETRY:
+			/* we come here if we received an RNR NAK */
+			if (qp->comp.rnr_retry > 0) {
+				if (qp->comp.rnr_retry != 7)
+					qp->comp.rnr_retry--;
+
+				/* don't start a retry flow until the
+				 * rnr timer has fired
+				 */
+				qp->req.wait_for_rnr_timer = 1;
+				rxe_dbg_qp(qp, "set rnr nak timer\n");
+				// TODO who protects from destroy_qp??
+				mod_timer(&qp->rnr_nak_timer,
+					  jiffies + rnrnak_jiffies(aeth_syn(pkt)
+						& ~AETH_TYPE_MASK));
+				goto exit;
+			} else {
+				rxe_counter_inc(rxe,
+						RXE_CNT_RNR_RETRY_EXCEEDED);
+				wqe->status = IB_WC_RNR_RETRY_EXC_ERR;
+				state = COMPST_ERROR;
+			}
+			break;
+
+		case COMPST_ERROR:
+			WARN_ON_ONCE(wqe->status == IB_WC_SUCCESS);
+			do_complete(qp, wqe);
+			rxe_qp_error(qp);
+			goto exit;
+		}
+	}
+
+	/* 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_completer
+	 */
+done:
+	ret = 0;
+	goto out;
+exit:
+	ret = -EAGAIN;
+out:
+	if (pkt)
+		free_pkt(pkt);
+	return ret;
+}