Revert to Fedora kernel-2.6.17-1.2187_FC5 patched with vs2.0.2.1; there are too many...
[linux-2.6.git] / drivers / infiniband / hw / ipath / ipath_rc.c
index 774d161..493b182 100644 (file)
@@ -1,5 +1,4 @@
 /*
- * Copyright (c) 2006 QLogic, Inc. All rights reserved.
  * Copyright (c) 2005, 2006 PathScale, Inc. All rights reserved.
  *
  * This software is available to you under a choice of one of two
@@ -32,7 +31,7 @@
  */
 
 #include "ipath_verbs.h"
-#include "ipath_common.h"
+#include "ips_common.h"
 
 /* cut down ridiculously long IB macro names */
 #define OP(x) IB_OPCODE_RC_##x
  * @qp: the QP who's SGE we're restarting
  * @wqe: the work queue to initialize the QP's SGE from
  *
- * The QP s_lock should be held and interrupts disabled.
+ * The QP s_lock should be held.
  */
 static void ipath_init_restart(struct ipath_qp *qp, struct ipath_swqe *wqe)
 {
        struct ipath_ibdev *dev;
        u32 len;
 
-       len = ((qp->s_psn - wqe->psn) & IPATH_PSN_MASK) *
+       len = ((qp->s_psn - wqe->psn) & IPS_PSN_MASK) *
                ib_mtu_enum_to_int(qp->path_mtu);
        qp->s_sge.sge = wqe->sg_list[0];
        qp->s_sge.sg_list = wqe->sg_list + 1;
@@ -73,10 +72,11 @@ static void ipath_init_restart(struct ipath_qp *qp, struct ipath_swqe *wqe)
  * Return bth0 if constructed; otherwise, return 0.
  * Note the QP s_lock must be held.
  */
-u32 ipath_make_rc_ack(struct ipath_qp *qp,
-                     struct ipath_other_headers *ohdr,
-                     u32 pmtu)
+static inline u32 ipath_make_rc_ack(struct ipath_qp *qp,
+                                   struct ipath_other_headers *ohdr,
+                                   u32 pmtu)
 {
+       struct ipath_sge_state *ss;
        u32 hwords;
        u32 len;
        u32 bth0;
@@ -90,12 +90,13 @@ u32 ipath_make_rc_ack(struct ipath_qp *qp,
         */
        switch (qp->s_ack_state) {
        case OP(RDMA_READ_REQUEST):
-               qp->s_cur_sge = &qp->s_rdma_sge;
+               ss = &qp->s_rdma_sge;
                len = qp->s_rdma_len;
                if (len > pmtu) {
                        len = pmtu;
                        qp->s_ack_state = OP(RDMA_READ_RESPONSE_FIRST);
-               } else
+               }
+               else
                        qp->s_ack_state = OP(RDMA_READ_RESPONSE_ONLY);
                qp->s_rdma_len -= len;
                bth0 = qp->s_ack_state << 24;
@@ -107,7 +108,7 @@ u32 ipath_make_rc_ack(struct ipath_qp *qp,
                qp->s_ack_state = OP(RDMA_READ_RESPONSE_MIDDLE);
                /* FALLTHROUGH */
        case OP(RDMA_READ_RESPONSE_MIDDLE):
-               qp->s_cur_sge = &qp->s_rdma_sge;
+               ss = &qp->s_rdma_sge;
                len = qp->s_rdma_len;
                if (len > pmtu)
                        len = pmtu;
@@ -126,50 +127,41 @@ u32 ipath_make_rc_ack(struct ipath_qp *qp,
                 * We have to prevent new requests from changing
                 * the r_sge state while a ipath_verbs_send()
                 * is in progress.
+                * Changing r_state allows the receiver
+                * to continue processing new packets.
+                * We do it here now instead of above so
+                * that we are sure the packet was sent before
+                * changing the state.
                 */
+               qp->r_state = OP(RDMA_READ_RESPONSE_LAST);
                qp->s_ack_state = OP(ACKNOWLEDGE);
-               bth0 = 0;
-               goto bail;
+               return 0;
 
        case OP(COMPARE_SWAP):
        case OP(FETCH_ADD):
-               qp->s_cur_sge = NULL;
+               ss = NULL;
                len = 0;
-               /*
-                * Set the s_ack_state so the receive interrupt handler
-                * won't try to send an ACK (out of order) until this one
-                * is actually sent.
-                */
-               qp->s_ack_state = OP(RDMA_READ_RESPONSE_LAST);
-               bth0 = OP(ATOMIC_ACKNOWLEDGE) << 24;
+               qp->r_state = OP(SEND_LAST);
+               qp->s_ack_state = OP(ACKNOWLEDGE);
+               bth0 = IB_OPCODE_ATOMIC_ACKNOWLEDGE << 24;
                ohdr->u.at.aeth = ipath_compute_aeth(qp);
-               ohdr->u.at.atomic_ack_eth = cpu_to_be64(qp->r_atomic_data);
+               ohdr->u.at.atomic_ack_eth = cpu_to_be64(qp->s_ack_atomic);
                hwords += sizeof(ohdr->u.at) / 4;
                break;
 
        default:
                /* Send a regular ACK. */
-               qp->s_cur_sge = NULL;
+               ss = NULL;
                len = 0;
-               /*
-                * Set the s_ack_state so the receive interrupt handler
-                * won't try to send an ACK (out of order) until this one
-                * is actually sent.
-                */
-               qp->s_ack_state = OP(RDMA_READ_RESPONSE_LAST);
-               bth0 = OP(ACKNOWLEDGE) << 24;
-               if (qp->s_nak_state)
-                       ohdr->u.aeth = cpu_to_be32((qp->r_msn & IPATH_MSN_MASK) |
-                                                   (qp->s_nak_state <<
-                                                    IPATH_AETH_CREDIT_SHIFT));
-               else
-                       ohdr->u.aeth = ipath_compute_aeth(qp);
+               qp->s_ack_state = OP(ACKNOWLEDGE);
+               bth0 = qp->s_ack_state << 24;
+               ohdr->u.aeth = ipath_compute_aeth(qp);
                hwords++;
        }
        qp->s_hdrwords = hwords;
+       qp->s_cur_sge = ss;
        qp->s_cur_size = len;
 
-bail:
        return bth0;
 }
 
@@ -182,11 +174,11 @@ bail:
  * @bth2p: pointer to the BTH PSN word
  *
  * Return 1 if constructed; otherwise, return 0.
- * Note the QP s_lock must be held and interrupts disabled.
+ * Note the QP s_lock must be held.
  */
-int ipath_make_rc_req(struct ipath_qp *qp,
-                     struct ipath_other_headers *ohdr,
-                     u32 pmtu, u32 *bth0p, u32 *bth2p)
+static inline int ipath_make_rc_req(struct ipath_qp *qp,
+                                   struct ipath_other_headers *ohdr,
+                                   u32 pmtu, u32 *bth0p, u32 *bth2p)
 {
        struct ipath_ibdev *dev = to_idev(qp->ibqp.device);
        struct ipath_sge_state *ss;
@@ -265,7 +257,7 @@ int ipath_make_rc_req(struct ipath_qp *qp,
                        break;
 
                case IB_WR_RDMA_WRITE:
-                       if (newreq && qp->s_lsn != (u32) -1)
+                       if (newreq)
                                qp->s_lsn++;
                        /* FALLTHROUGH */
                case IB_WR_RDMA_WRITE_WITH_IMM:
@@ -291,7 +283,8 @@ int ipath_make_rc_req(struct ipath_qp *qp,
                        else {
                                qp->s_state =
                                        OP(RDMA_WRITE_ONLY_WITH_IMMEDIATE);
-                               /* Immediate data comes after RETH */
+                               /* Immediate data comes
+                                * after RETH */
                                ohdr->u.rc.imm_data = wqe->wr.imm_data;
                                hwords += 1;
                                if (wqe->wr.send_flags & IB_SEND_SOLICITED)
@@ -311,8 +304,7 @@ int ipath_make_rc_req(struct ipath_qp *qp,
                        qp->s_state = OP(RDMA_READ_REQUEST);
                        hwords += sizeof(ohdr->u.rc.reth) / 4;
                        if (newreq) {
-                               if (qp->s_lsn != (u32) -1)
-                                       qp->s_lsn++;
+                               qp->s_lsn++;
                                /*
                                 * Adjust s_next_psn to count the
                                 * expected number of responses.
@@ -343,8 +335,7 @@ int ipath_make_rc_req(struct ipath_qp *qp,
                                wqe->wr.wr.atomic.compare_add);
                        hwords += sizeof(struct ib_atomic_eth) / 4;
                        if (newreq) {
-                               if (qp->s_lsn != (u32) -1)
-                                       qp->s_lsn++;
+                               qp->s_lsn++;
                                wqe->lpsn = wqe->psn;
                        }
                        if (++qp->s_cur == qp->s_size)
@@ -361,14 +352,9 @@ int ipath_make_rc_req(struct ipath_qp *qp,
                        if (qp->s_tail >= qp->s_size)
                                qp->s_tail = 0;
                }
-               bth2 |= qp->s_psn++ & IPATH_PSN_MASK;
+               bth2 |= qp->s_psn++ & IPS_PSN_MASK;
                if ((int)(qp->s_psn - qp->s_next_psn) > 0)
                        qp->s_next_psn = qp->s_psn;
-               /*
-                * Put the QP on the pending list so lost ACKs will cause
-                * a retry.  More than one request can be pending so the
-                * QP may already be on the dev->pending list.
-                */
                spin_lock(&dev->pending_lock);
                if (list_empty(&qp->timerwait))
                        list_add_tail(&qp->timerwait,
@@ -378,8 +364,8 @@ int ipath_make_rc_req(struct ipath_qp *qp,
 
        case OP(RDMA_READ_RESPONSE_FIRST):
                /*
-                * This case can only happen if a send is restarted.
-                * See ipath_restart_rc().
+                * This case can only happen if a send is restarted.  See
+                * ipath_restart_rc().
                 */
                ipath_init_restart(qp, wqe);
                /* FALLTHROUGH */
@@ -387,7 +373,7 @@ int ipath_make_rc_req(struct ipath_qp *qp,
                qp->s_state = OP(SEND_MIDDLE);
                /* FALLTHROUGH */
        case OP(SEND_MIDDLE):
-               bth2 = qp->s_psn++ & IPATH_PSN_MASK;
+               bth2 = qp->s_psn++ & IPS_PSN_MASK;
                if ((int)(qp->s_psn - qp->s_next_psn) > 0)
                        qp->s_next_psn = qp->s_psn;
                ss = &qp->s_sge;
@@ -429,7 +415,7 @@ int ipath_make_rc_req(struct ipath_qp *qp,
                qp->s_state = OP(RDMA_WRITE_MIDDLE);
                /* FALLTHROUGH */
        case OP(RDMA_WRITE_MIDDLE):
-               bth2 = qp->s_psn++ & IPATH_PSN_MASK;
+               bth2 = qp->s_psn++ & IPS_PSN_MASK;
                if ((int)(qp->s_psn - qp->s_next_psn) > 0)
                        qp->s_next_psn = qp->s_psn;
                ss = &qp->s_sge;
@@ -466,7 +452,7 @@ int ipath_make_rc_req(struct ipath_qp *qp,
                 * See ipath_restart_rc().
                 */
                ipath_init_restart(qp, wqe);
-               len = ((qp->s_psn - wqe->psn) & IPATH_PSN_MASK) * pmtu;
+               len = ((qp->s_psn - wqe->psn) & IPS_PSN_MASK) * pmtu;
                ohdr->u.rc.reth.vaddr =
                        cpu_to_be64(wqe->wr.wr.rdma.remote_addr + len);
                ohdr->u.rc.reth.rkey =
@@ -474,7 +460,7 @@ int ipath_make_rc_req(struct ipath_qp *qp,
                ohdr->u.rc.reth.length = cpu_to_be32(qp->s_len);
                qp->s_state = OP(RDMA_READ_REQUEST);
                hwords += sizeof(ohdr->u.rc.reth) / 4;
-               bth2 = qp->s_psn++ & IPATH_PSN_MASK;
+               bth2 = qp->s_psn++ & IPS_PSN_MASK;
                if ((int)(qp->s_psn - qp->s_next_psn) > 0)
                        qp->s_next_psn = qp->s_psn;
                ss = NULL;
@@ -510,169 +496,189 @@ done:
        return 0;
 }
 
+static inline void ipath_make_rc_grh(struct ipath_qp *qp,
+                                    struct ib_global_route *grh,
+                                    u32 nwords)
+{
+       struct ipath_ibdev *dev = to_idev(qp->ibqp.device);
+
+       /* GRH header size in 32-bit words. */
+       qp->s_hdrwords += 10;
+       qp->s_hdr.u.l.grh.version_tclass_flow =
+               cpu_to_be32((6 << 28) |
+                           (grh->traffic_class << 20) |
+                           grh->flow_label);
+       qp->s_hdr.u.l.grh.paylen =
+               cpu_to_be16(((qp->s_hdrwords - 12) + nwords +
+                            SIZE_OF_CRC) << 2);
+       /* next_hdr is defined by C8-7 in ch. 8.4.1 */
+       qp->s_hdr.u.l.grh.next_hdr = 0x1B;
+       qp->s_hdr.u.l.grh.hop_limit = grh->hop_limit;
+       /* The SGID is 32-bit aligned. */
+       qp->s_hdr.u.l.grh.sgid.global.subnet_prefix = dev->gid_prefix;
+       qp->s_hdr.u.l.grh.sgid.global.interface_id =
+               ipath_layer_get_guid(dev->dd);
+       qp->s_hdr.u.l.grh.dgid = grh->dgid;
+}
+
 /**
- * send_rc_ack - Construct an ACK packet and send it
- * @qp: a pointer to the QP
+ * ipath_do_rc_send - perform a send on an RC QP
+ * @data: contains a pointer to the QP
  *
- * This is called from ipath_rc_rcv() and only uses the receive
- * side QP state.
- * Note that RDMA reads are handled in the send side QP state and tasklet.
+ * Process entries in the send work queue until credit or queue is
+ * exhausted.  Only allow one CPU to send a packet per QP (tasklet).
+ * Otherwise, after we drop the QP s_lock, two threads could send
+ * packets out of order.
  */
-static void send_rc_ack(struct ipath_qp *qp)
+void ipath_do_rc_send(unsigned long data)
 {
+       struct ipath_qp *qp = (struct ipath_qp *)data;
        struct ipath_ibdev *dev = to_idev(qp->ibqp.device);
+       unsigned long flags;
        u16 lrh0;
+       u32 nwords;
+       u32 extra_bytes;
        u32 bth0;
-       u32 hwords;
-       struct ipath_ib_header hdr;
+       u32 bth2;
+       u32 pmtu = ib_mtu_enum_to_int(qp->path_mtu);
        struct ipath_other_headers *ohdr;
 
-       /* Construct the header. */
-       ohdr = &hdr.u.oth;
-       lrh0 = IPATH_LRH_BTH;
-       /* header size in 32-bit words LRH+BTH+AETH = (8+12+4)/4. */
-       hwords = 6;
-       if (unlikely(qp->remote_ah_attr.ah_flags & IB_AH_GRH)) {
-               hwords += ipath_make_grh(dev, &hdr.u.l.grh,
-                                        &qp->remote_ah_attr.grh,
-                                        hwords, 0);
-               ohdr = &hdr.u.l.oth;
-               lrh0 = IPATH_LRH_GRH;
-       }
-       /* read pkey_index w/o lock (its atomic) */
-       bth0 = ipath_layer_get_pkey(dev->dd, qp->s_pkey_index);
-       if (qp->r_nak_state)
-               ohdr->u.aeth = cpu_to_be32((qp->r_msn & IPATH_MSN_MASK) |
-                                           (qp->r_nak_state <<
-                                            IPATH_AETH_CREDIT_SHIFT));
-       else
-               ohdr->u.aeth = ipath_compute_aeth(qp);
-       if (qp->r_ack_state >= OP(COMPARE_SWAP)) {
-               bth0 |= OP(ATOMIC_ACKNOWLEDGE) << 24;
-               ohdr->u.at.atomic_ack_eth = cpu_to_be64(qp->r_atomic_data);
-               hwords += sizeof(ohdr->u.at.atomic_ack_eth) / 4;
-       } else
-               bth0 |= OP(ACKNOWLEDGE) << 24;
-       lrh0 |= qp->remote_ah_attr.sl << 4;
-       hdr.lrh[0] = cpu_to_be16(lrh0);
-       hdr.lrh[1] = cpu_to_be16(qp->remote_ah_attr.dlid);
-       hdr.lrh[2] = cpu_to_be16(hwords + SIZE_OF_CRC);
-       hdr.lrh[3] = cpu_to_be16(ipath_layer_get_lid(dev->dd));
-       ohdr->bth[0] = cpu_to_be32(bth0);
-       ohdr->bth[1] = cpu_to_be32(qp->remote_qpn);
-       ohdr->bth[2] = cpu_to_be32(qp->r_ack_psn & IPATH_PSN_MASK);
+       if (test_and_set_bit(IPATH_S_BUSY, &qp->s_flags))
+               goto bail;
+
+       if (unlikely(qp->remote_ah_attr.dlid ==
+                    ipath_layer_get_lid(dev->dd))) {
+               struct ib_wc wc;
 
-       /*
-        * If we can send the ACK, clear the ACK state.
-        */
-       if (ipath_verbs_send(dev->dd, hwords, (u32 *) &hdr, 0, NULL) == 0) {
-               qp->r_ack_state = OP(ACKNOWLEDGE);
-               dev->n_unicast_xmit++;
-       } else {
                /*
-                * We are out of PIO buffers at the moment.
-                * Pass responsibility for sending the ACK to the
-                * send tasklet so that when a PIO buffer becomes
-                * available, the ACK is sent ahead of other outgoing
-                * packets.
+                * Pass in an uninitialized ib_wc to be consistent with
+                * other places where ipath_ruc_loopback() is called.
                 */
-               dev->n_rc_qacks++;
-               spin_lock_irq(&qp->s_lock);
-               /* Don't coalesce if a RDMA read or atomic is pending. */
-               if (qp->s_ack_state == OP(ACKNOWLEDGE) ||
-                   qp->s_ack_state < OP(RDMA_READ_REQUEST)) {
-                       qp->s_ack_state = qp->r_ack_state;
-                       qp->s_nak_state = qp->r_nak_state;
-                       qp->s_ack_psn = qp->r_ack_psn;
-                       qp->r_ack_state = OP(ACKNOWLEDGE);
-               }
-               spin_unlock_irq(&qp->s_lock);
-
-               /* Call ipath_do_rc_send() in another thread. */
-               tasklet_hi_schedule(&qp->s_task);
-       }
-}
-
-/**
- * reset_psn - reset the QP state to send starting from PSN
- * @qp: the QP
- * @psn: the packet sequence number to restart at
- *
- * This is called from ipath_rc_rcv() to process an incoming RC ACK
- * for the given QP.
- * Called at interrupt level with the QP s_lock held.
- */
-static void reset_psn(struct ipath_qp *qp, u32 psn)
-{
-       u32 n = qp->s_last;
-       struct ipath_swqe *wqe = get_swqe_ptr(qp, n);
-       u32 opcode;
-
-       qp->s_cur = n;
-
-       /*
-        * If we are starting the request from the beginning,
-        * let the normal send code handle initialization.
-        */
-       if (ipath_cmp24(psn, wqe->psn) <= 0) {
-               qp->s_state = OP(SEND_LAST);
-               goto done;
+               ipath_ruc_loopback(qp, &wc);
+               goto clear;
        }
 
-       /* Find the work request opcode corresponding to the given PSN. */
-       opcode = wqe->wr.opcode;
-       for (;;) {
-               int diff;
+       ohdr = &qp->s_hdr.u.oth;
+       if (qp->remote_ah_attr.ah_flags & IB_AH_GRH)
+               ohdr = &qp->s_hdr.u.l.oth;
 
-               if (++n == qp->s_size)
-                       n = 0;
-               if (n == qp->s_tail)
-                       break;
-               wqe = get_swqe_ptr(qp, n);
-               diff = ipath_cmp24(psn, wqe->psn);
-               if (diff < 0)
-                       break;
-               qp->s_cur = n;
+again:
+       /* Check for a constructed packet to be sent. */
+       if (qp->s_hdrwords != 0) {
                /*
-                * If we are starting the request from the beginning,
-                * let the normal send code handle initialization.
+                * If no PIO bufs are available, return.  An interrupt will
+                * call ipath_ib_piobufavail() when one is available.
                 */
-               if (diff == 0) {
-                       qp->s_state = OP(SEND_LAST);
-                       goto done;
+               _VERBS_INFO("h %u %p\n", qp->s_hdrwords, &qp->s_hdr);
+               _VERBS_INFO("d %u %p %u %p %u %u %u %u\n", qp->s_cur_size,
+                           qp->s_cur_sge->sg_list,
+                           qp->s_cur_sge->num_sge,
+                           qp->s_cur_sge->sge.vaddr,
+                           qp->s_cur_sge->sge.sge_length,
+                           qp->s_cur_sge->sge.length,
+                           qp->s_cur_sge->sge.m,
+                           qp->s_cur_sge->sge.n);
+               if (ipath_verbs_send(dev->dd, qp->s_hdrwords,
+                                    (u32 *) &qp->s_hdr, qp->s_cur_size,
+                                    qp->s_cur_sge)) {
+                       ipath_no_bufs_available(qp, dev);
+                       goto bail;
                }
-               opcode = wqe->wr.opcode;
+               dev->n_unicast_xmit++;
+               /* Record that we sent the packet and s_hdr is empty. */
+               qp->s_hdrwords = 0;
        }
 
        /*
-        * Set the state to restart in the middle of a request.
-        * Don't change the s_sge, s_cur_sge, or s_cur_size.
-        * See ipath_do_rc_send().
+        * The lock is needed to synchronize between setting
+        * qp->s_ack_state, resend timer, and post_send().
         */
-       switch (opcode) {
-       case IB_WR_SEND:
-       case IB_WR_SEND_WITH_IMM:
-               qp->s_state = OP(RDMA_READ_RESPONSE_FIRST);
-               break;
+       spin_lock_irqsave(&qp->s_lock, flags);
 
-       case IB_WR_RDMA_WRITE:
-       case IB_WR_RDMA_WRITE_WITH_IMM:
-               qp->s_state = OP(RDMA_READ_RESPONSE_LAST);
-               break;
+       /* Sending responses has higher priority over sending requests. */
+       if (qp->s_ack_state != OP(ACKNOWLEDGE) &&
+           (bth0 = ipath_make_rc_ack(qp, ohdr, pmtu)) != 0)
+               bth2 = qp->s_ack_psn++ & IPS_PSN_MASK;
+       else if (!ipath_make_rc_req(qp, ohdr, pmtu, &bth0, &bth2))
+               goto done;
 
-       case IB_WR_RDMA_READ:
-               qp->s_state = OP(RDMA_READ_RESPONSE_MIDDLE);
-               break;
+       spin_unlock_irqrestore(&qp->s_lock, flags);
 
-       default:
-               /*
-                * This case shouldn't happen since its only
-                * one PSN per req.
-                */
-               qp->s_state = OP(SEND_LAST);
+       /* Construct the header. */
+       extra_bytes = (4 - qp->s_cur_size) & 3;
+       nwords = (qp->s_cur_size + extra_bytes) >> 2;
+       lrh0 = IPS_LRH_BTH;
+       if (unlikely(qp->remote_ah_attr.ah_flags & IB_AH_GRH)) {
+               ipath_make_rc_grh(qp, &qp->remote_ah_attr.grh, nwords);
+               lrh0 = IPS_LRH_GRH;
        }
+       lrh0 |= qp->remote_ah_attr.sl << 4;
+       qp->s_hdr.lrh[0] = cpu_to_be16(lrh0);
+       qp->s_hdr.lrh[1] = cpu_to_be16(qp->remote_ah_attr.dlid);
+       qp->s_hdr.lrh[2] = cpu_to_be16(qp->s_hdrwords + nwords +
+                                      SIZE_OF_CRC);
+       qp->s_hdr.lrh[3] = cpu_to_be16(ipath_layer_get_lid(dev->dd));
+       bth0 |= ipath_layer_get_pkey(dev->dd, qp->s_pkey_index);
+       bth0 |= extra_bytes << 20;
+       ohdr->bth[0] = cpu_to_be32(bth0);
+       ohdr->bth[1] = cpu_to_be32(qp->remote_qpn);
+       ohdr->bth[2] = cpu_to_be32(bth2);
+
+       /* Check for more work to do. */
+       goto again;
+
 done:
-       qp->s_psn = psn;
+       spin_unlock_irqrestore(&qp->s_lock, flags);
+clear:
+       clear_bit(IPATH_S_BUSY, &qp->s_flags);
+bail:
+       return;
+}
+
+static void send_rc_ack(struct ipath_qp *qp)
+{
+       struct ipath_ibdev *dev = to_idev(qp->ibqp.device);
+       u16 lrh0;
+       u32 bth0;
+       struct ipath_other_headers *ohdr;
+
+       /* Construct the header. */
+       ohdr = &qp->s_hdr.u.oth;
+       lrh0 = IPS_LRH_BTH;
+       /* header size in 32-bit words LRH+BTH+AETH = (8+12+4)/4. */
+       qp->s_hdrwords = 6;
+       if (unlikely(qp->remote_ah_attr.ah_flags & IB_AH_GRH)) {
+               ipath_make_rc_grh(qp, &qp->remote_ah_attr.grh, 0);
+               ohdr = &qp->s_hdr.u.l.oth;
+               lrh0 = IPS_LRH_GRH;
+       }
+       bth0 = ipath_layer_get_pkey(dev->dd, qp->s_pkey_index);
+       ohdr->u.aeth = ipath_compute_aeth(qp);
+       if (qp->s_ack_state >= OP(COMPARE_SWAP)) {
+               bth0 |= IB_OPCODE_ATOMIC_ACKNOWLEDGE << 24;
+               ohdr->u.at.atomic_ack_eth = cpu_to_be64(qp->s_ack_atomic);
+               qp->s_hdrwords += sizeof(ohdr->u.at.atomic_ack_eth) / 4;
+       }
+       else
+               bth0 |= OP(ACKNOWLEDGE) << 24;
+       lrh0 |= qp->remote_ah_attr.sl << 4;
+       qp->s_hdr.lrh[0] = cpu_to_be16(lrh0);
+       qp->s_hdr.lrh[1] = cpu_to_be16(qp->remote_ah_attr.dlid);
+       qp->s_hdr.lrh[2] = cpu_to_be16(qp->s_hdrwords + SIZE_OF_CRC);
+       qp->s_hdr.lrh[3] = cpu_to_be16(ipath_layer_get_lid(dev->dd));
+       ohdr->bth[0] = cpu_to_be32(bth0);
+       ohdr->bth[1] = cpu_to_be32(qp->remote_qpn);
+       ohdr->bth[2] = cpu_to_be32(qp->s_ack_psn & IPS_PSN_MASK);
+
+       /*
+        * If we can send the ACK, clear the ACK state.
+        */
+       if (ipath_verbs_send(dev->dd, qp->s_hdrwords, (u32 *) &qp->s_hdr,
+                            0, NULL) == 0) {
+               qp->s_ack_state = OP(ACKNOWLEDGE);
+               dev->n_rc_qacks++;
+               dev->n_unicast_xmit++;
+       }
 }
 
 /**
@@ -681,12 +687,13 @@ done:
  * @psn: packet sequence number for the request
  * @wc: the work completion request
  *
- * The QP s_lock should be held and interrupts disabled.
+ * The QP s_lock should be held.
  */
 void ipath_restart_rc(struct ipath_qp *qp, u32 psn, struct ib_wc *wc)
 {
        struct ipath_swqe *wqe = get_swqe_ptr(qp, qp->s_last);
        struct ipath_ibdev *dev;
+       u32 n;
 
        /*
         * If there are no requests pending, we are done.
@@ -728,7 +735,62 @@ void ipath_restart_rc(struct ipath_qp *qp, u32 psn, struct ib_wc *wc)
        else
                dev->n_rc_resends += (int)qp->s_psn - (int)psn;
 
-       reset_psn(qp, psn);
+       /*
+        * If we are starting the request from the beginning, let the normal
+        * send code handle initialization.
+        */
+       qp->s_cur = qp->s_last;
+       if (ipath_cmp24(psn, wqe->psn) <= 0) {
+               qp->s_state = OP(SEND_LAST);
+               qp->s_psn = wqe->psn;
+       } else {
+               n = qp->s_cur;
+               for (;;) {
+                       if (++n == qp->s_size)
+                               n = 0;
+                       if (n == qp->s_tail) {
+                               if (ipath_cmp24(psn, qp->s_next_psn) >= 0) {
+                                       qp->s_cur = n;
+                                       wqe = get_swqe_ptr(qp, n);
+                               }
+                               break;
+                       }
+                       wqe = get_swqe_ptr(qp, n);
+                       if (ipath_cmp24(psn, wqe->psn) < 0)
+                               break;
+                       qp->s_cur = n;
+               }
+               qp->s_psn = psn;
+
+               /*
+                * Reset the state to restart in the middle of a request.
+                * Don't change the s_sge, s_cur_sge, or s_cur_size.
+                * See ipath_do_rc_send().
+                */
+               switch (wqe->wr.opcode) {
+               case IB_WR_SEND:
+               case IB_WR_SEND_WITH_IMM:
+                       qp->s_state = OP(RDMA_READ_RESPONSE_FIRST);
+                       break;
+
+               case IB_WR_RDMA_WRITE:
+               case IB_WR_RDMA_WRITE_WITH_IMM:
+                       qp->s_state = OP(RDMA_READ_RESPONSE_LAST);
+                       break;
+
+               case IB_WR_RDMA_READ:
+                       qp->s_state =
+                               OP(RDMA_READ_RESPONSE_MIDDLE);
+                       break;
+
+               default:
+                       /*
+                        * This case shouldn't happen since its only
+                        * one PSN per req.
+                        */
+                       qp->s_state = OP(SEND_LAST);
+               }
+       }
 
 done:
        tasklet_hi_schedule(&qp->s_task);
@@ -737,15 +799,77 @@ bail:
        return;
 }
 
+/**
+ * reset_psn - reset the QP state to send starting from PSN
+ * @qp: the QP
+ * @psn: the packet sequence number to restart at
+ *
+ * This is called from ipath_rc_rcv() to process an incoming RC ACK
+ * for the given QP.
+ * Called at interrupt level with the QP s_lock held.
+ */
+static void reset_psn(struct ipath_qp *qp, u32 psn)
+{
+       struct ipath_swqe *wqe;
+       u32 n;
+
+       n = qp->s_cur;
+       wqe = get_swqe_ptr(qp, n);
+       for (;;) {
+               if (++n == qp->s_size)
+                       n = 0;
+               if (n == qp->s_tail) {
+                       if (ipath_cmp24(psn, qp->s_next_psn) >= 0) {
+                               qp->s_cur = n;
+                               wqe = get_swqe_ptr(qp, n);
+                       }
+                       break;
+               }
+               wqe = get_swqe_ptr(qp, n);
+               if (ipath_cmp24(psn, wqe->psn) < 0)
+                       break;
+               qp->s_cur = n;
+       }
+       qp->s_psn = psn;
+
+       /*
+        * Set the state to restart in the middle of a
+        * request.  Don't change the s_sge, s_cur_sge, or
+        * s_cur_size.  See ipath_do_rc_send().
+        */
+       switch (wqe->wr.opcode) {
+       case IB_WR_SEND:
+       case IB_WR_SEND_WITH_IMM:
+               qp->s_state = OP(RDMA_READ_RESPONSE_FIRST);
+               break;
+
+       case IB_WR_RDMA_WRITE:
+       case IB_WR_RDMA_WRITE_WITH_IMM:
+               qp->s_state = OP(RDMA_READ_RESPONSE_LAST);
+               break;
+
+       case IB_WR_RDMA_READ:
+               qp->s_state = OP(RDMA_READ_RESPONSE_MIDDLE);
+               break;
+
+       default:
+               /*
+                * This case shouldn't happen since its only
+                * one PSN per req.
+                */
+               qp->s_state = OP(SEND_LAST);
+       }
+}
+
 /**
  * do_rc_ack - process an incoming RC ACK
  * @qp: the QP the ACK came in on
  * @psn: the packet sequence number of the ACK
  * @opcode: the opcode of the request that resulted in the ACK
  *
- * This is called from ipath_rc_rcv_resp() to process an incoming RC ACK
+ * This is called from ipath_rc_rcv() to process an incoming RC ACK
  * for the given QP.
- * Called at interrupt level with the QP s_lock held and interrupts disabled.
+ * Called at interrupt level with the QP s_lock held.
  * Returns 1 if OK, 0 if current operation should be aborted (NAK).
  */
 static int do_rc_ack(struct ipath_qp *qp, u32 aeth, u32 psn, int opcode)
@@ -882,16 +1006,26 @@ static int do_rc_ack(struct ipath_qp *qp, u32 aeth, u32 psn, int opcode)
                if (qp->s_last == qp->s_tail)
                        goto bail;
 
-               /* The last valid PSN is the previous PSN. */
-               qp->s_last_psn = psn - 1;
+               /* The last valid PSN seen is the previous request's. */
+               qp->s_last_psn = wqe->psn - 1;
 
                dev->n_rc_resends += (int)qp->s_psn - (int)psn;
 
-               reset_psn(qp, psn);
+               /*
+                * If we are starting the request from the beginning, let
+                * the normal send code handle initialization.
+                */
+               qp->s_cur = qp->s_last;
+               wqe = get_swqe_ptr(qp, qp->s_cur);
+               if (ipath_cmp24(psn, wqe->psn) <= 0) {
+                       qp->s_state = OP(SEND_LAST);
+                       qp->s_psn = wqe->psn;
+               } else
+                       reset_psn(qp, psn);
 
                qp->s_rnr_timeout =
-                       ib_ipath_rnr_table[(aeth >> IPATH_AETH_CREDIT_SHIFT) &
-                                          IPATH_AETH_CREDIT_MASK];
+                       ib_ipath_rnr_table[(aeth >> IPS_AETH_CREDIT_SHIFT) &
+                                          IPS_AETH_CREDIT_MASK];
                ipath_insert_rnr_queue(qp);
                goto bail;
 
@@ -899,8 +1033,8 @@ static int do_rc_ack(struct ipath_qp *qp, u32 aeth, u32 psn, int opcode)
                /* The last valid PSN seen is the previous request's. */
                if (qp->s_last != qp->s_tail)
                        qp->s_last_psn = wqe->psn - 1;
-               switch ((aeth >> IPATH_AETH_CREDIT_SHIFT) &
-                       IPATH_AETH_CREDIT_MASK) {
+               switch ((aeth >> IPS_AETH_CREDIT_SHIFT) &
+                       IPS_AETH_CREDIT_MASK) {
                case 0: /* PSN sequence error */
                        dev->n_seq_naks++;
                        /*
@@ -1048,33 +1182,32 @@ static inline void ipath_rc_rcv_resp(struct ipath_ibdev *dev,
                        goto ack_done;
                }
        rdma_read:
-               if (unlikely(qp->s_state != OP(RDMA_READ_REQUEST)))
-                       goto ack_done;
-               if (unlikely(tlen != (hdrsize + pmtu + 4)))
-                       goto ack_done;
-               if (unlikely(pmtu >= qp->s_len))
-                       goto ack_done;
-               /* We got a response so update the timeout. */
-               if (unlikely(qp->s_last == qp->s_tail ||
-                            get_swqe_ptr(qp, qp->s_last)->wr.opcode !=
-                            IB_WR_RDMA_READ))
-                       goto ack_done;
-               spin_lock(&dev->pending_lock);
-               if (qp->s_rnr_timeout == 0 && !list_empty(&qp->timerwait))
-                       list_move_tail(&qp->timerwait,
-                                      &dev->pending[dev->pending_index]);
-               spin_unlock(&dev->pending_lock);
-               /*
-                * Update the RDMA receive state but do the copy w/o
-                * holding the locks and blocking interrupts.
-                * XXX Yet another place that affects relaxed RDMA order
-                * since we don't want s_sge modified.
-                */
-               qp->s_len -= pmtu;
-               qp->s_last_psn = psn;
-               spin_unlock_irqrestore(&qp->s_lock, flags);
-               ipath_copy_sge(&qp->s_sge, data, pmtu);
-               goto bail;
+       if (unlikely(qp->s_state != OP(RDMA_READ_REQUEST)))
+               goto ack_done;
+       if (unlikely(tlen != (hdrsize + pmtu + 4)))
+               goto ack_done;
+       if (unlikely(pmtu >= qp->s_len))
+               goto ack_done;
+       /* We got a response so update the timeout. */
+       if (unlikely(qp->s_last == qp->s_tail ||
+                    get_swqe_ptr(qp, qp->s_last)->wr.opcode !=
+                    IB_WR_RDMA_READ))
+               goto ack_done;
+       spin_lock(&dev->pending_lock);
+       if (qp->s_rnr_timeout == 0 && !list_empty(&qp->timerwait))
+               list_move_tail(&qp->timerwait,
+                              &dev->pending[dev->pending_index]);
+       spin_unlock(&dev->pending_lock);
+       /*
+        * Update the RDMA receive state but do the copy w/o holding the
+        * locks and blocking interrupts.  XXX Yet another place that
+        * affects relaxed RDMA order since we don't want s_sge modified.
+        */
+       qp->s_len -= pmtu;
+       qp->s_last_psn = psn;
+       spin_unlock_irqrestore(&qp->s_lock, flags);
+       ipath_copy_sge(&qp->s_sge, data, pmtu);
+       goto bail;
 
        case OP(RDMA_READ_RESPONSE_LAST):
                /* ACKs READ req. */
@@ -1097,12 +1230,18 @@ static inline void ipath_rc_rcv_resp(struct ipath_ibdev *dev,
                 * ICRC (4).
                 */
                if (unlikely(tlen <= (hdrsize + pad + 8))) {
-                       /* XXX Need to generate an error CQ entry. */
+                       /*
+                        * XXX Need to generate an error CQ
+                        * entry.
+                        */
                        goto ack_done;
                }
                tlen -= hdrsize + pad + 8;
                if (unlikely(tlen != qp->s_len)) {
-                       /* XXX Need to generate an error CQ entry. */
+                       /*
+                        * XXX Need to generate an error CQ
+                        * entry.
+                        */
                        goto ack_done;
                }
                if (!header_in_data)
@@ -1115,12 +1254,9 @@ static inline void ipath_rc_rcv_resp(struct ipath_ibdev *dev,
                if (do_rc_ack(qp, aeth, psn, OP(RDMA_READ_RESPONSE_LAST))) {
                        /*
                         * Change the state so we contimue
-                        * processing new requests and wake up the
-                        * tasklet if there are posted sends.
+                        * processing new requests.
                         */
                        qp->s_state = OP(SEND_LAST);
-                       if (qp->s_tail != qp->s_head)
-                               tasklet_hi_schedule(&qp->s_task);
                }
                goto ack_done;
        }
@@ -1166,16 +1302,18 @@ static inline int ipath_rc_rcv_error(struct ipath_ibdev *dev,
                 * Don't queue the NAK if a RDMA read, atomic, or
                 * NAK is pending though.
                 */
-               if (qp->s_ack_state != OP(ACKNOWLEDGE) ||
-                   qp->r_nak_state != 0)
+               spin_lock(&qp->s_lock);
+               if ((qp->s_ack_state >= OP(RDMA_READ_REQUEST) &&
+                    qp->s_ack_state != IB_OPCODE_ACKNOWLEDGE) ||
+                   qp->s_nak_state != 0) {
+                       spin_unlock(&qp->s_lock);
                        goto done;
-               if (qp->r_ack_state < OP(COMPARE_SWAP)) {
-                       qp->r_ack_state = OP(SEND_ONLY);
-                       qp->r_nak_state = IB_NAK_PSN_ERROR;
-                       /* Use the expected PSN. */
-                       qp->r_ack_psn = qp->r_psn;
                }
-               goto send_ack;
+               qp->s_ack_state = OP(SEND_ONLY);
+               qp->s_nak_state = IB_NAK_PSN_ERROR;
+               /* Use the expected PSN. */
+               qp->s_ack_psn = qp->r_psn;
+               goto resched;
        }
 
        /*
@@ -1189,7 +1327,27 @@ static inline int ipath_rc_rcv_error(struct ipath_ibdev *dev,
         * send the earliest so that RDMA reads can be restarted at
         * the requester's expected PSN.
         */
-       if (opcode == OP(RDMA_READ_REQUEST)) {
+       spin_lock(&qp->s_lock);
+       if (qp->s_ack_state != IB_OPCODE_ACKNOWLEDGE &&
+           ipath_cmp24(psn, qp->s_ack_psn) >= 0) {
+               if (qp->s_ack_state < IB_OPCODE_RDMA_READ_REQUEST)
+                       qp->s_ack_psn = psn;
+               spin_unlock(&qp->s_lock);
+               goto done;
+       }
+       switch (opcode) {
+       case OP(RDMA_READ_REQUEST):
+               /*
+                * We have to be careful to not change s_rdma_sge
+                * while ipath_do_rc_send() is using it and not
+                * holding the s_lock.
+                */
+               if (qp->s_ack_state != OP(ACKNOWLEDGE) &&
+                   qp->s_ack_state >= IB_OPCODE_RDMA_READ_REQUEST) {
+                       spin_unlock(&qp->s_lock);
+                       dev->n_rdma_dup_busy++;
+                       goto done;
+               }
                /* RETH comes after BTH */
                if (!header_in_data)
                        reth = &ohdr->u.rc.reth;
@@ -1197,22 +1355,6 @@ static inline int ipath_rc_rcv_error(struct ipath_ibdev *dev,
                        reth = (struct ib_reth *)data;
                        data += sizeof(*reth);
                }
-               /*
-                * If we receive a duplicate RDMA request, it means the
-                * requester saw a sequence error and needs to restart
-                * from an earlier point.  We can abort the current
-                * RDMA read send in that case.
-                */
-               spin_lock_irq(&qp->s_lock);
-               if (qp->s_ack_state != OP(ACKNOWLEDGE) &&
-                   (qp->s_hdrwords || ipath_cmp24(psn, qp->s_ack_psn) >= 0)) {
-                       /*
-                        * We are already sending earlier requested data.
-                        * Don't abort it to send later out of sequence data.
-                        */
-                       spin_unlock_irq(&qp->s_lock);
-                       goto done;
-               }
                qp->s_rdma_len = be32_to_cpu(reth->length);
                if (qp->s_rdma_len != 0) {
                        u32 rkey = be32_to_cpu(reth->rkey);
@@ -1226,10 +1368,8 @@ static inline int ipath_rc_rcv_error(struct ipath_ibdev *dev,
                        ok = ipath_rkey_ok(dev, &qp->s_rdma_sge,
                                           qp->s_rdma_len, vaddr, rkey,
                                           IB_ACCESS_REMOTE_READ);
-                       if (unlikely(!ok)) {
-                               spin_unlock_irq(&qp->s_lock);
+                       if (unlikely(!ok))
                                goto done;
-                       }
                } else {
                        qp->s_rdma_sge.sg_list = NULL;
                        qp->s_rdma_sge.num_sge = 0;
@@ -1238,44 +1378,25 @@ static inline int ipath_rc_rcv_error(struct ipath_ibdev *dev,
                        qp->s_rdma_sge.sge.length = 0;
                        qp->s_rdma_sge.sge.sge_length = 0;
                }
-               qp->s_ack_state = opcode;
-               qp->s_ack_psn = psn;
-               spin_unlock_irq(&qp->s_lock);
-               tasklet_hi_schedule(&qp->s_task);
-               goto send_ack;
-       }
-
-       /*
-        * A pending RDMA read will ACK anything before it so
-        * ignore earlier duplicate requests.
-        */
-       if (qp->s_ack_state != OP(ACKNOWLEDGE))
-               goto done;
+               break;
 
-       /*
-        * If an ACK is pending, don't replace the pending ACK
-        * with an earlier one since the later one will ACK the earlier.
-        * Also, if we already have a pending atomic, send it.
-        */
-       if (qp->r_ack_state != OP(ACKNOWLEDGE) &&
-           (ipath_cmp24(psn, qp->r_ack_psn) <= 0 ||
-            qp->r_ack_state >= OP(COMPARE_SWAP)))
-               goto send_ack;
-       switch (opcode) {
        case OP(COMPARE_SWAP):
        case OP(FETCH_ADD):
                /*
-                * Check for the PSN of the last atomic operation
+                * Check for the PSN of the last atomic operations
                 * performed and resend the result if found.
                 */
-               if ((psn & IPATH_PSN_MASK) != qp->r_atomic_psn)
+               if ((psn & IPS_PSN_MASK) != qp->r_atomic_psn) {
+                       spin_unlock(&qp->s_lock);
                        goto done;
+               }
+               qp->s_ack_atomic = qp->r_atomic_data;
                break;
        }
-       qp->r_ack_state = opcode;
-       qp->r_nak_state = 0;
-       qp->r_ack_psn = psn;
-send_ack:
+       qp->s_ack_state = opcode;
+       qp->s_nak_state = 0;
+       qp->s_ack_psn = psn;
+resched:
        return 0;
 
 done:
@@ -1303,6 +1424,7 @@ void ipath_rc_rcv(struct ipath_ibdev *dev, struct ipath_ib_header *hdr,
        u32 hdrsize;
        u32 psn;
        u32 pad;
+       unsigned long flags;
        struct ib_wc wc;
        u32 pmtu = ib_mtu_enum_to_int(qp->path_mtu);
        int diff;
@@ -1331,6 +1453,11 @@ void ipath_rc_rcv(struct ipath_ibdev *dev, struct ipath_ib_header *hdr,
                } else
                        psn = be32_to_cpu(ohdr->bth[2]);
        }
+       /*
+        * The opcode is in the low byte when its in network order
+        * (top byte when in host order).
+        */
+       opcode = be32_to_cpu(ohdr->bth[0]) >> 24;
 
        /*
         * Process responses (ACKs) before anything else.  Note that the
@@ -1338,21 +1465,22 @@ void ipath_rc_rcv(struct ipath_ibdev *dev, struct ipath_ib_header *hdr,
         * queue rather than the expected receive packet sequence number.
         * In other words, this QP is the requester.
         */
-       opcode = be32_to_cpu(ohdr->bth[0]) >> 24;
        if (opcode >= OP(RDMA_READ_RESPONSE_FIRST) &&
            opcode <= OP(ATOMIC_ACKNOWLEDGE)) {
                ipath_rc_rcv_resp(dev, ohdr, data, tlen, qp, opcode, psn,
                                  hdrsize, pmtu, header_in_data);
-               goto done;
+               goto bail;
        }
 
+       spin_lock_irqsave(&qp->r_rq.lock, flags);
+
        /* Compute 24 bits worth of difference. */
        diff = ipath_cmp24(psn, qp->r_psn);
        if (unlikely(diff)) {
                if (ipath_rc_rcv_error(dev, ohdr, data, qp, opcode,
                                       psn, diff, header_in_data))
                        goto done;
-               goto send_ack;
+               goto resched;
        }
 
        /* Check for opcode sequence errors. */
@@ -1364,19 +1492,22 @@ void ipath_rc_rcv(struct ipath_ibdev *dev, struct ipath_ib_header *hdr,
                    opcode == OP(SEND_LAST_WITH_IMMEDIATE))
                        break;
        nack_inv:
-               /*
-                * A NAK will ACK earlier sends and RDMA writes.
-                * Don't queue the NAK if a RDMA read, atomic, or NAK
-                * is pending though.
-                */
-               if (qp->r_ack_state >= OP(COMPARE_SWAP))
-                       goto send_ack;
-               /* XXX Flush WQEs */
-               qp->state = IB_QPS_ERR;
-               qp->r_ack_state = OP(SEND_ONLY);
-               qp->r_nak_state = IB_NAK_INVALID_REQUEST;
-               qp->r_ack_psn = qp->r_psn;
-               goto send_ack;
+       /*
+        * A NAK will ACK earlier sends and RDMA writes.  Don't queue the
+        * NAK if a RDMA read, atomic, or NAK is pending though.
+        */
+       spin_lock(&qp->s_lock);
+       if (qp->s_ack_state >= OP(RDMA_READ_REQUEST) &&
+           qp->s_ack_state != IB_OPCODE_ACKNOWLEDGE) {
+               spin_unlock(&qp->s_lock);
+               goto done;
+       }
+       /* XXX Flush WQEs */
+       qp->state = IB_QPS_ERR;
+       qp->s_ack_state = OP(SEND_ONLY);
+       qp->s_nak_state = IB_NAK_INVALID_REQUEST;
+       qp->s_ack_psn = qp->r_psn;
+       goto resched;
 
        case OP(RDMA_WRITE_FIRST):
        case OP(RDMA_WRITE_MIDDLE):
@@ -1386,6 +1517,20 @@ void ipath_rc_rcv(struct ipath_ibdev *dev, struct ipath_ib_header *hdr,
                        break;
                goto nack_inv;
 
+       case OP(RDMA_READ_REQUEST):
+       case OP(COMPARE_SWAP):
+       case OP(FETCH_ADD):
+               /*
+                * Drop all new requests until a response has been sent.  A
+                * new request then ACKs the RDMA response we sent.  Relaxed
+                * ordering would allow new requests to be processed but we
+                * would need to keep a queue of rwqe's for all that are in
+                * progress.  Note that we can't RNR NAK this request since
+                * the RDMA READ or atomic response is already queued to be
+                * sent (unless we implement a response send queue).
+                */
+               goto done;
+
        default:
                if (opcode == OP(SEND_MIDDLE) ||
                    opcode == OP(SEND_LAST) ||
@@ -1394,11 +1539,6 @@ void ipath_rc_rcv(struct ipath_ibdev *dev, struct ipath_ib_header *hdr,
                    opcode == OP(RDMA_WRITE_LAST) ||
                    opcode == OP(RDMA_WRITE_LAST_WITH_IMMEDIATE))
                        goto nack_inv;
-               /*
-                * Note that it is up to the requester to not send a new
-                * RDMA read or atomic operation before receiving an ACK
-                * for the previous operation.
-                */
                break;
        }
 
@@ -1415,12 +1555,17 @@ void ipath_rc_rcv(struct ipath_ibdev *dev, struct ipath_ib_header *hdr,
                         * Don't queue the NAK if a RDMA read or atomic
                         * is pending though.
                         */
-                       if (qp->r_ack_state >= OP(COMPARE_SWAP))
-                               goto send_ack;
-                       qp->r_ack_state = OP(SEND_ONLY);
-                       qp->r_nak_state = IB_RNR_NAK | qp->r_min_rnr_timer;
-                       qp->r_ack_psn = qp->r_psn;
-                       goto send_ack;
+                       spin_lock(&qp->s_lock);
+                       if (qp->s_ack_state >=
+                           OP(RDMA_READ_REQUEST) &&
+                           qp->s_ack_state != IB_OPCODE_ACKNOWLEDGE) {
+                               spin_unlock(&qp->s_lock);
+                               goto done;
+                       }
+                       qp->s_ack_state = OP(SEND_ONLY);
+                       qp->s_nak_state = IB_RNR_NAK | qp->s_min_rnr_timer;
+                       qp->s_ack_psn = qp->r_psn;
+                       goto resched;
                }
                qp->r_rcv_len = 0;
                /* FALLTHROUGH */
@@ -1477,7 +1622,7 @@ void ipath_rc_rcv(struct ipath_ibdev *dev, struct ipath_ib_header *hdr,
                if (unlikely(wc.byte_len > qp->r_len))
                        goto nack_inv;
                ipath_copy_sge(&qp->r_sge, data, tlen);
-               qp->r_msn++;
+               atomic_inc(&qp->msn);
                if (opcode == OP(RDMA_WRITE_LAST) ||
                    opcode == OP(RDMA_WRITE_ONLY))
                        break;
@@ -1521,8 +1666,29 @@ void ipath_rc_rcv(struct ipath_ibdev *dev, struct ipath_ib_header *hdr,
                        ok = ipath_rkey_ok(dev, &qp->r_sge,
                                           qp->r_len, vaddr, rkey,
                                           IB_ACCESS_REMOTE_WRITE);
-                       if (unlikely(!ok))
-                               goto nack_acc;
+                       if (unlikely(!ok)) {
+                       nack_acc:
+                               /*
+                                * A NAK will ACK earlier sends and RDMA
+                                * writes.  Don't queue the NAK if a RDMA
+                                * read, atomic, or NAK is pending though.
+                                */
+                               spin_lock(&qp->s_lock);
+                               if (qp->s_ack_state >=
+                                   OP(RDMA_READ_REQUEST) &&
+                                   qp->s_ack_state !=
+                                   IB_OPCODE_ACKNOWLEDGE) {
+                                       spin_unlock(&qp->s_lock);
+                                       goto done;
+                               }
+                               /* XXX Flush WQEs */
+                               qp->state = IB_QPS_ERR;
+                               qp->s_ack_state = OP(RDMA_WRITE_ONLY);
+                               qp->s_nak_state =
+                                       IB_NAK_REMOTE_ACCESS_ERROR;
+                               qp->s_ack_psn = qp->r_psn;
+                               goto resched;
+                       }
                } else {
                        qp->r_sge.sg_list = NULL;
                        qp->r_sge.sge.mr = NULL;
@@ -1549,10 +1715,12 @@ void ipath_rc_rcv(struct ipath_ibdev *dev, struct ipath_ib_header *hdr,
                        reth = (struct ib_reth *)data;
                        data += sizeof(*reth);
                }
-               if (unlikely(!(qp->qp_access_flags &
-                              IB_ACCESS_REMOTE_READ)))
-                       goto nack_acc;
-               spin_lock_irq(&qp->s_lock);
+               spin_lock(&qp->s_lock);
+               if (qp->s_ack_state != OP(ACKNOWLEDGE) &&
+                   qp->s_ack_state >= IB_OPCODE_RDMA_READ_REQUEST) {
+                       spin_unlock(&qp->s_lock);
+                       goto done;
+               }
                qp->s_rdma_len = be32_to_cpu(reth->length);
                if (qp->s_rdma_len != 0) {
                        u32 rkey = be32_to_cpu(reth->rkey);
@@ -1564,7 +1732,7 @@ void ipath_rc_rcv(struct ipath_ibdev *dev, struct ipath_ib_header *hdr,
                                           qp->s_rdma_len, vaddr, rkey,
                                           IB_ACCESS_REMOTE_READ);
                        if (unlikely(!ok)) {
-                               spin_unlock_irq(&qp->s_lock);
+                               spin_unlock(&qp->s_lock);
                                goto nack_acc;
                        }
                        /*
@@ -1581,25 +1749,21 @@ void ipath_rc_rcv(struct ipath_ibdev *dev, struct ipath_ib_header *hdr,
                        qp->s_rdma_sge.sge.length = 0;
                        qp->s_rdma_sge.sge.sge_length = 0;
                }
+               if (unlikely(!(qp->qp_access_flags &
+                              IB_ACCESS_REMOTE_READ)))
+                       goto nack_acc;
                /*
                 * We need to increment the MSN here instead of when we
                 * finish sending the result since a duplicate request would
                 * increment it more than once.
                 */
-               qp->r_msn++;
-
+               atomic_inc(&qp->msn);
                qp->s_ack_state = opcode;
+               qp->s_nak_state = 0;
                qp->s_ack_psn = psn;
-               spin_unlock_irq(&qp->s_lock);
-
                qp->r_psn++;
                qp->r_state = opcode;
-               qp->r_nak_state = 0;
-
-               /* Call ipath_do_rc_send() in another thread. */
-               tasklet_hi_schedule(&qp->s_task);
-
-               goto done;
+               goto rdmadone;
 
        case OP(COMPARE_SWAP):
        case OP(FETCH_ADD): {
@@ -1628,7 +1792,7 @@ void ipath_rc_rcv(struct ipath_ibdev *dev, struct ipath_ib_header *hdr,
                        goto nack_acc;
                /* Perform atomic OP and save result. */
                sdata = be64_to_cpu(ateth->swap_data);
-               spin_lock_irq(&dev->pending_lock);
+               spin_lock(&dev->pending_lock);
                qp->r_atomic_data = *(u64 *) qp->r_sge.sge.vaddr;
                if (opcode == OP(FETCH_ADD))
                        *(u64 *) qp->r_sge.sge.vaddr =
@@ -1636,9 +1800,9 @@ void ipath_rc_rcv(struct ipath_ibdev *dev, struct ipath_ib_header *hdr,
                else if (qp->r_atomic_data ==
                         be64_to_cpu(ateth->compare_data))
                        *(u64 *) qp->r_sge.sge.vaddr = sdata;
-               spin_unlock_irq(&dev->pending_lock);
-               qp->r_msn++;
-               qp->r_atomic_psn = psn & IPATH_PSN_MASK;
+               spin_unlock(&dev->pending_lock);
+               atomic_inc(&qp->msn);
+               qp->r_atomic_psn = psn & IPS_PSN_MASK;
                psn |= 1 << 31;
                break;
        }
@@ -1649,39 +1813,44 @@ void ipath_rc_rcv(struct ipath_ibdev *dev, struct ipath_ib_header *hdr,
        }
        qp->r_psn++;
        qp->r_state = opcode;
-       qp->r_nak_state = 0;
        /* Send an ACK if requested or required. */
        if (psn & (1 << 31)) {
                /*
                 * Coalesce ACKs unless there is a RDMA READ or
                 * ATOMIC pending.
                 */
-               if (qp->r_ack_state < OP(COMPARE_SWAP)) {
-                       qp->r_ack_state = opcode;
-                       qp->r_ack_psn = psn;
+               spin_lock(&qp->s_lock);
+               if (qp->s_ack_state == OP(ACKNOWLEDGE) ||
+                   qp->s_ack_state < IB_OPCODE_RDMA_READ_REQUEST) {
+                       qp->s_ack_state = opcode;
+                       qp->s_nak_state = 0;
+                       qp->s_ack_psn = psn;
+                       qp->s_ack_atomic = qp->r_atomic_data;
+                       goto resched;
                }
-               goto send_ack;
+               spin_unlock(&qp->s_lock);
        }
-       goto done;
+done:
+       spin_unlock_irqrestore(&qp->r_rq.lock, flags);
+       goto bail;
 
-nack_acc:
+resched:
        /*
-        * A NAK will ACK earlier sends and RDMA writes.
-        * Don't queue the NAK if a RDMA read, atomic, or NAK
-        * is pending though.
+        * Try to send ACK right away but not if ipath_do_rc_send() is
+        * active.
         */
-       if (qp->r_ack_state < OP(COMPARE_SWAP)) {
-               /* XXX Flush WQEs */
-               qp->state = IB_QPS_ERR;
-               qp->r_ack_state = OP(RDMA_WRITE_ONLY);
-               qp->r_nak_state = IB_NAK_REMOTE_ACCESS_ERROR;
-               qp->r_ack_psn = qp->r_psn;
-       }
-send_ack:
-       /* Send ACK right away unless the send tasklet has a pending ACK. */
-       if (qp->s_ack_state == OP(ACKNOWLEDGE))
+       if (qp->s_hdrwords == 0 &&
+           (qp->s_ack_state < IB_OPCODE_RDMA_READ_REQUEST ||
+            qp->s_ack_state >= IB_OPCODE_COMPARE_SWAP))
                send_rc_ack(qp);
 
-done:
+rdmadone:
+       spin_unlock(&qp->s_lock);
+       spin_unlock_irqrestore(&qp->r_rq.lock, flags);
+
+       /* Call ipath_do_rc_send() in another thread. */
+       tasklet_hi_schedule(&qp->s_task);
+
+bail:
        return;
 }