new file mode 100644
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+/*
+ * Copyright (c) 2015 Mellanox Technologies Ltd. All rights reserved.
+ * Copyright (c) 2015 System Fabric Works, Inc. All rights reserved.
+ *
+ * This software is available to you under a choice of one of two
+ * licenses. You may choose to be licensed under the terms of the GNU
+ * General Public License (GPL) Version 2, available from the file
+ * COPYING in the main directory of this source tree, or the
+ * OpenIB.org BSD license below:
+ *
+ * Redistribution and use in source and binary forms, with or
+ * without modification, are permitted provided that the following
+ * conditions are met:
+ *
+ * - Redistributions of source code must retain the above
+ * copyright notice, this list of conditions and the following
+ * disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following
+ * disclaimer in the documentation and/or other materials
+ * provided with the distribution.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#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_FAST_REG_MR: return IB_WC_FAST_REG_MR;
+
+ default:
+ return 0xff;
+ }
+}
+
+void retransmit_timer(unsigned long data)
+{
+ struct rxe_qp *qp = (struct rxe_qp *)data;
+
+ if (qp->valid) {
+ qp->comp.timeout = 1;
+ rxe_run_task(&qp->comp.task, 1);
+ }
+}
+
+void rxe_comp_queue_pkt(struct rxe_dev *rxe, 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;
+ rxe_run_task(&qp->comp.task, must_sched);
+}
+
+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);
+ *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;
+}
+
+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
+ return COMPST_DONE;
+ } else if ((diff > 0) && (wqe->mask & WR_ATOMIC_OR_READ_MASK)) {
+ return COMPST_ERROR_RETRY;
+ } 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;
+
+ /* 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:
+ if (pkt->opcode != IB_OPCODE_RC_RDMA_READ_RESPONSE_MIDDLE &&
+ pkt->opcode != IB_OPCODE_RC_RDMA_READ_RESPONSE_LAST) {
+ return COMPST_ERROR;
+ }
+ break;
+ default:
+ WARN_ON(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;
+
+ /* Fall through (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) {
+ 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:
+ 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) {
+ qp->comp.psn = pkt->psn;
+ if (qp->req.wait_psn) {
+ qp->req.wait_psn = 0;
+ rxe_run_task(&qp->req.task, 1);
+ }
+ }
+ 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:
+ pr_warn("unexpected nak %x\n", syn);
+ wqe->status = IB_WC_REM_OP_ERR;
+ return COMPST_ERROR;
+ }
+
+ default:
+ return COMPST_ERROR;
+ }
+ break;
+
+ default:
+ pr_warn("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)
+{
+ struct rxe_dev *rxe = to_rdev(qp->ibqp.device);
+ int ret;
+
+ ret = copy_data(rxe, qp->pd, IB_ACCESS_LOCAL_WRITE,
+ &wqe->dma, payload_addr(pkt),
+ payload_size(pkt), to_mem_obj, NULL);
+ if (ret)
+ return COMPST_ERROR;
+
+ if (wqe->dma.resid == 0 && (pkt->mask & RXE_END_MASK))
+ return COMPST_COMP_ACK;
+ else
+ 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)
+{
+ struct rxe_dev *rxe = to_rdev(qp->ibqp.device);
+ int ret;
+
+ u64 atomic_orig = atmack_orig(pkt);
+
+ ret = copy_data(rxe, qp->pd, IB_ACCESS_LOCAL_WRITE,
+ &wqe->dma, &atomic_orig,
+ sizeof(u64), to_mem_obj, NULL);
+ if (ret)
+ return COMPST_ERROR;
+ else
+ return COMPST_COMP_ACK;
+}
+
+static void make_send_cqe(struct rxe_qp *qp, struct rxe_send_wqe *wqe,
+ struct rxe_cqe *cqe)
+{
+ memset(cqe, 0, sizeof(*cqe));
+
+ if (!qp->is_user) {
+ struct ib_wc *wc = &cqe->ibwc;
+
+ wc->wr_id = wqe->wr.wr_id;
+ wc->status = wqe->status;
+ wc->opcode = wr_to_wc_opcode(wqe->wr.opcode);
+ wc->byte_len = wqe->dma.length;
+ wc->qp = &qp->ibqp;
+ } else {
+ struct ib_uverbs_wc *uwc = &cqe->uibwc;
+
+ uwc->wr_id = wqe->wr.wr_id;
+ uwc->status = wqe->status;
+ uwc->opcode = wr_to_wc_opcode(wqe->wr.opcode);
+ uwc->byte_len = wqe->dma.length;
+ uwc->qp_num = qp->ibqp.qp_num;
+ }
+}
+
+static void do_complete(struct rxe_qp *qp, struct rxe_send_wqe *wqe)
+{
+ struct rxe_cqe cqe;
+
+ if ((qp->sq_sig_type == IB_SIGNAL_ALL_WR) ||
+ (wqe->wr.send_flags & IB_SEND_SIGNALED) ||
+ (qp->req.state == QP_STATE_ERROR)) {
+ make_send_cqe(qp, wqe, &cqe);
+ rxe_cq_post(qp->scq, &cqe, 0);
+ }
+
+ advance_consumer(qp->sq.queue);
+
+ /*
+ * 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_run_task(&qp->req.task, 1);
+ }
+}
+
+static inline enum comp_state complete_ack(struct rxe_qp *qp,
+ struct rxe_pkt_info *pkt,
+ struct rxe_send_wqe *wqe)
+{
+ unsigned long flags;
+
+ 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_run_task(&qp->req.task, 1);
+ }
+ }
+
+ if (unlikely(qp->req.state == QP_STATE_DRAIN)) {
+ /* state_lock used by requester & completer */
+ spin_lock_irqsave(&qp->state_lock, flags);
+ if ((qp->req.state == QP_STATE_DRAIN) &&
+ (qp->comp.psn == qp->req.psn)) {
+ qp->req.state = QP_STATE_DRAINED;
+ 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);
+ }
+ } else {
+ spin_unlock_irqrestore(&qp->state_lock, flags);
+ }
+ }
+
+ 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)
+{
+ qp->comp.opcode = -1;
+
+ if (pkt) {
+ 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_run_task(&qp->req.task, 1);
+ }
+ }
+
+ do_complete(qp, wqe);
+
+ return COMPST_GET_WQE;
+}
+
+int rxe_completer(void *arg)
+{
+ struct rxe_qp *qp = (struct rxe_qp *)arg;
+ struct rxe_send_wqe *wqe = wqe;
+ struct sk_buff *skb = NULL;
+ struct rxe_pkt_info *pkt = NULL;
+ enum comp_state state;
+
+ if (!qp->valid) {
+ while ((skb = skb_dequeue(&qp->resp_pkts))) {
+ rxe_drop_ref(qp);
+ kfree_skb(skb);
+ }
+ skb = NULL;
+ pkt = NULL;
+
+ while (queue_head(qp->sq.queue))
+ advance_consumer(qp->sq.queue);
+
+ goto exit;
+ }
+
+ if (qp->req.state == QP_STATE_ERROR) {
+ while ((skb = skb_dequeue(&qp->resp_pkts))) {
+ rxe_drop_ref(qp);
+ kfree_skb(skb);
+ }
+ skb = NULL;
+ pkt = NULL;
+
+ while ((wqe = queue_head(qp->sq.queue))) {
+ wqe->status = IB_WC_WR_FLUSH_ERR;
+ do_complete(qp, wqe);
+ }
+
+ goto exit;
+ }
+
+ if (qp->req.state == QP_STATE_RESET) {
+ while ((skb = skb_dequeue(&qp->resp_pkts))) {
+ rxe_drop_ref(qp);
+ kfree_skb(skb);
+ }
+ skb = NULL;
+ pkt = NULL;
+
+ while (queue_head(qp->sq.queue))
+ advance_consumer(qp->sq.queue);
+
+ goto exit;
+ }
+
+ 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) {
+ pr_debug("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_run_task(&qp->req.task, 1);
+ }
+
+ state = COMPST_DONE;
+ break;
+
+ case COMPST_DONE:
+ if (pkt) {
+ rxe_drop_ref(pkt->qp);
+ kfree_skb(skb);
+ }
+ goto done;
+
+ case COMPST_EXIT:
+ if (qp->comp.timeout_retry && wqe) {
+ state = COMPST_ERROR_RETRY;
+ break;
+ }
+
+ /* re reset the timeout counter if
+ * (1) QP is type RC
+ * (2) the QP is alive
+ * (3) 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)
+ * (4) the timeout parameter is set
+ */
+ if ((qp_type(qp) == IB_QPT_RC) &&
+ (qp->req.state == QP_STATE_READY) &&
+ (psn_compare(qp->req.psn, qp->comp.psn) > 0) &&
+ qp->qp_timeout_jiffies)
+ mod_timer(&qp->retrans_timer,
+ jiffies + qp->qp_timeout_jiffies);
+ 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 (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 send queue next time around
+ */
+ qp->req.need_retry = 1;
+ rxe_run_task(&qp->req.task, 1);
+ }
+ goto exit;
+ } else {
+ wqe->status = IB_WC_RETRY_EXC_ERR;
+ state = COMPST_ERROR;
+ }
+ break;
+
+ case COMPST_RNR_RETRY:
+ if (qp->comp.rnr_retry > 0) {
+ if (qp->comp.rnr_retry != 7)
+ qp->comp.rnr_retry--;
+
+ qp->req.need_retry = 1;
+ pr_debug("set rnr nak timer\n");
+ mod_timer(&qp->rnr_nak_timer,
+ jiffies + rnrnak_jiffies(aeth_syn(pkt)
+ & ~AETH_TYPE_MASK));
+ goto exit;
+ } else {
+ wqe->status = IB_WC_RNR_RETRY_EXC_ERR;
+ state = COMPST_ERROR;
+ }
+ break;
+
+ case COMPST_ERROR:
+ do_complete(qp, wqe);
+ rxe_qp_error(qp);
+ goto exit;
+ }
+ }
+
+exit:
+ /* we come here if we are done with processing and want the task to
+ * exit from the loop calling us
+ */
+ return -EAGAIN;
+
+done:
+ /* we come here if we have processed a packet we want the task to call
+ * us again to see if there is anything else to do
+ */
+ return 0;
+}