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    Subject[PATCH 14 of 20] ipath - infiniband RC protocol support
    Date
    From
    Signed-off-by: Bryan O'Sullivan <bos@pathscale.com>

    diff -r e6b07a6f5a64 -r 70e3edb0d82d drivers/infiniband/hw/ipath/ipath_rc.c
    --- /dev/null Thu Jan 1 00:00:00 1970 +0000
    +++ b/drivers/infiniband/hw/ipath/ipath_rc.c Thu Mar 9 16:16:37 2006 -0800
    @@ -0,0 +1,1753 @@
    +/*
    + * Copyright (c) 2005, 2006 PathScale, 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 "ipath_verbs.h"
    +#include "ips_common.h"
    +
    +/**
    + * ipath_init_restart- initialize the qp->s_sge after a restart
    + * @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.
    + */
    +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) & 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;
    + qp->s_sge.num_sge = wqe->wr.num_sge;
    + ipath_skip_sge(&qp->s_sge, len);
    + qp->s_len = wqe->length - len;
    + dev = to_idev(qp->ibqp.device);
    + spin_lock(&dev->pending_lock);
    + if (qp->timerwait.next == LIST_POISON1)
    + list_add_tail(&qp->timerwait,
    + &dev->pending[dev->pending_index]);
    + spin_unlock(&dev->pending_lock);
    +}
    +
    +/**
    + * ipath_do_rc_send - perform a send on an RC QP
    + * @data: contains a pointer to the QP
    + *
    + * 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.
    + */
    +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);
    + struct ipath_swqe *wqe;
    + struct ipath_sge_state *ss;
    + unsigned long flags;
    + u16 lrh0;
    + u32 hwords;
    + u32 nwords;
    + u32 extra_bytes;
    + u32 bth0;
    + u32 bth2;
    + u32 pmtu = ib_mtu_enum_to_int(qp->path_mtu);
    + u32 len;
    + struct ipath_other_headers *ohdr;
    + char newreq;
    +
    + if (test_and_set_bit(IPATH_S_BUSY, &qp->s_flags))
    + return;
    +
    + if (unlikely(qp->remote_ah_attr.dlid ==
    + ipath_layer_get_lid(dev->dd))) {
    + struct ib_wc wc;
    +
    + /*
    + * Pass in an uninitialized ib_wc to be consistent with
    + * other places where ipath_ruc_loopback() is called.
    + */
    + ipath_ruc_loopback(qp, &wc);
    + clear_bit(IPATH_S_BUSY, &qp->s_flags);
    + return;
    + }
    +
    + ohdr = &qp->s_hdr.u.oth;
    + if (qp->remote_ah_attr.ah_flags & IB_AH_GRH)
    + ohdr = &qp->s_hdr.u.l.oth;
    +
    +again:
    + /* Check for a constructed packet to be sent. */
    + if (qp->s_hdrwords != 0) {
    + /*
    + * If no PIO bufs are available, return.
    + * An interrupt will call ipath_ib_piobufavail()
    + * when one is available.
    + */
    + 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);
    + return;
    + }
    + dev->n_unicast_xmit++;
    + /* Record that we sent the packet and s_hdr is empty. */
    + qp->s_hdrwords = 0;
    + }
    +
    + lrh0 = IPS_LRH_BTH;
    + /* header size in 32-bit words LRH+BTH = (8+12)/4. */
    + hwords = 5;
    +
    + /*
    + * The lock is needed to synchronize between
    + * setting qp->s_ack_state, resend timer, and post_send().
    + */
    + spin_lock_irqsave(&qp->s_lock, flags);
    +
    + bth0 = ipath_layer_get_pkey(dev->dd, qp->s_pkey_index);
    +
    + /* Sending responses has higher priority over sending requests. */
    + if (qp->s_ack_state != IB_OPCODE_RC_ACKNOWLEDGE) {
    + /*
    + * Send a response. Note that we are in the responder's
    + * side of the QP context.
    + */
    + switch (qp->s_ack_state) {
    + case IB_OPCODE_RC_RDMA_READ_REQUEST:
    + ss = &qp->s_rdma_sge;
    + len = qp->s_rdma_len;
    + if (len > pmtu) {
    + len = pmtu;
    + qp->s_ack_state =
    + IB_OPCODE_RC_RDMA_READ_RESPONSE_FIRST;
    + } else
    + qp->s_ack_state =
    + IB_OPCODE_RC_RDMA_READ_RESPONSE_ONLY;
    + qp->s_rdma_len -= len;
    + bth0 |= qp->s_ack_state << 24;
    + ohdr->u.aeth = ipath_compute_aeth(qp);
    + hwords++;
    + break;
    +
    + case IB_OPCODE_RC_RDMA_READ_RESPONSE_FIRST:
    + qp->s_ack_state =
    + IB_OPCODE_RC_RDMA_READ_RESPONSE_MIDDLE;
    + /* FALLTHROUGH */
    + case IB_OPCODE_RC_RDMA_READ_RESPONSE_MIDDLE:
    + ss = &qp->s_rdma_sge;
    + len = qp->s_rdma_len;
    + if (len > pmtu)
    + len = pmtu;
    + else {
    + ohdr->u.aeth = ipath_compute_aeth(qp);
    + hwords++;
    + qp->s_ack_state =
    + IB_OPCODE_RC_RDMA_READ_RESPONSE_LAST;
    + }
    + qp->s_rdma_len -= len;
    + bth0 |= qp->s_ack_state << 24;
    + break;
    +
    + case IB_OPCODE_RC_RDMA_READ_RESPONSE_LAST:
    + case IB_OPCODE_RC_RDMA_READ_RESPONSE_ONLY:
    + /*
    + * 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 = IB_OPCODE_RC_RDMA_READ_RESPONSE_LAST;
    + qp->s_ack_state = IB_OPCODE_RC_ACKNOWLEDGE;
    + goto send_req;
    +
    + case IB_OPCODE_RC_COMPARE_SWAP:
    + case IB_OPCODE_RC_FETCH_ADD:
    + ss = NULL;
    + len = 0;
    + qp->r_state = IB_OPCODE_RC_SEND_LAST;
    + qp->s_ack_state = IB_OPCODE_RC_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->s_ack_atomic);
    + hwords += sizeof(ohdr->u.at) / 4;
    + break;
    +
    + default:
    + /* Send a regular ACK. */
    + ss = NULL;
    + len = 0;
    + qp->s_ack_state = IB_OPCODE_RC_ACKNOWLEDGE;
    + bth0 |= qp->s_ack_state << 24;
    + ohdr->u.aeth = ipath_compute_aeth(qp);
    + hwords++;
    + }
    + bth2 = qp->s_ack_psn++ & IPS_PSN_MASK;
    + } else {
    + send_req:
    + if (!(ib_ipath_state_ops[qp->state] &
    + IPATH_PROCESS_SEND_OK) || qp->s_rnr_timeout)
    + goto done;
    +
    + /* Send a request. */
    + wqe = get_swqe_ptr(qp, qp->s_cur);
    + switch (qp->s_state) {
    + default:
    + /*
    + * Resend an old request or start a new one.
    + *
    + * We keep track of the current SWQE so that
    + * we don't reset the "furthest progress" state
    + * if we need to back up.
    + */
    + newreq = 0;
    + if (qp->s_cur == qp->s_tail) {
    + /* Check if send work queue is empty. */
    + if (qp->s_tail == qp->s_head)
    + goto done;
    + qp->s_psn = wqe->psn = qp->s_next_psn;
    + newreq = 1;
    + }
    + /*
    + * Note that we have to be careful not to modify the
    + * original work request since we may need to resend
    + * it.
    + */
    + qp->s_sge.sge = wqe->sg_list[0];
    + qp->s_sge.sg_list = wqe->sg_list + 1;
    + qp->s_sge.num_sge = wqe->wr.num_sge;
    + qp->s_len = len = wqe->length;
    + ss = &qp->s_sge;
    + bth2 = 0;
    + switch (wqe->wr.opcode) {
    + case IB_WR_SEND:
    + case IB_WR_SEND_WITH_IMM:
    + /* If no credit, return. */
    + if (qp->s_lsn != (u32) -1 &&
    + ipath_cmp24(wqe->ssn,
    + qp->s_lsn + 1) > 0)
    + goto done;
    + wqe->lpsn = wqe->psn;
    + if (len > pmtu) {
    + wqe->lpsn += (len - 1) / pmtu;
    + qp->s_state =
    + IB_OPCODE_RC_SEND_FIRST;
    + len = pmtu;
    + break;
    + }
    + if (wqe->wr.opcode == IB_WR_SEND)
    + qp->s_state =
    + IB_OPCODE_RC_SEND_ONLY;
    + else {
    + qp->s_state =
    + IB_OPCODE_RC_SEND_ONLY_WITH_IMMEDIATE;
    + /*
    + * Immediate data comes after the
    + * BTH
    + */
    + ohdr->u.imm_data = wqe->wr.imm_data;
    + hwords += 1;
    + }
    + if (wqe->wr.send_flags & IB_SEND_SOLICITED)
    + bth0 |= 1 << 23;
    + bth2 = 1 << 31; /* Request ACK. */
    + if (++qp->s_cur == qp->s_size)
    + qp->s_cur = 0;
    + break;
    +
    + case IB_WR_RDMA_WRITE:
    + if (newreq)
    + qp->s_lsn++;
    + /* FALLTHROUGH */
    + case IB_WR_RDMA_WRITE_WITH_IMM:
    + /* If no credit, return. */
    + if (qp->s_lsn != (u32) -1 &&
    + ipath_cmp24(wqe->ssn,
    + qp->s_lsn + 1) > 0)
    + goto done;
    + ohdr->u.rc.reth.vaddr =
    + cpu_to_be64(wqe->wr.wr.rdma.remote_addr);
    + ohdr->u.rc.reth.rkey =
    + cpu_to_be32(wqe->wr.wr.rdma.rkey);
    + ohdr->u.rc.reth.length = cpu_to_be32(len);
    + hwords += sizeof(struct ib_reth) / 4;
    + wqe->lpsn = wqe->psn;
    + if (len > pmtu) {
    + wqe->lpsn += (len - 1) / pmtu;
    + qp->s_state =
    + IB_OPCODE_RC_RDMA_WRITE_FIRST;
    + len = pmtu;
    + break;
    + }
    + if (wqe->wr.opcode == IB_WR_RDMA_WRITE)
    + qp->s_state =
    + IB_OPCODE_RC_RDMA_WRITE_ONLY;
    + else {
    + qp->s_state =
    + IB_OPCODE_RC_RDMA_WRITE_ONLY_WITH_IMMEDIATE;
    + /* Immediate data comes after RETH */
    + ohdr->u.rc.imm_data = wqe->wr.imm_data;
    + hwords += 1;
    + if (wqe->wr.
    + send_flags & IB_SEND_SOLICITED)
    + bth0 |= 1 << 23;
    + }
    + bth2 = 1 << 31; /* Request ACK. */
    + if (++qp->s_cur == qp->s_size)
    + qp->s_cur = 0;
    + break;
    +
    + case IB_WR_RDMA_READ:
    + ohdr->u.rc.reth.vaddr =
    + cpu_to_be64(wqe->wr.wr.rdma.remote_addr);
    + ohdr->u.rc.reth.rkey =
    + cpu_to_be32(wqe->wr.wr.rdma.rkey);
    + ohdr->u.rc.reth.length = cpu_to_be32(len);
    + qp->s_state = IB_OPCODE_RC_RDMA_READ_REQUEST;
    + hwords += sizeof(ohdr->u.rc.reth) / 4;
    + if (newreq) {
    + qp->s_lsn++;
    + /*
    + * Adjust s_next_psn to count the
    + * expected number of responses.
    + */
    + if (len > pmtu)
    + qp->s_next_psn +=
    + (len - 1) / pmtu;
    + wqe->lpsn = qp->s_next_psn++;
    + }
    + ss = NULL;
    + len = 0;
    + if (++qp->s_cur == qp->s_size)
    + qp->s_cur = 0;
    + break;
    +
    + case IB_WR_ATOMIC_CMP_AND_SWP:
    + case IB_WR_ATOMIC_FETCH_AND_ADD:
    + qp->s_state = (wqe->wr.opcode ==
    + IB_WR_ATOMIC_CMP_AND_SWP)
    + ? IB_OPCODE_RC_COMPARE_SWAP
    + : IB_OPCODE_RC_FETCH_ADD;
    + ohdr->u.atomic_eth.vaddr =
    + cpu_to_be64(wqe->wr.wr.atomic.remote_addr);
    + ohdr->u.atomic_eth.rkey =
    + cpu_to_be32(wqe->wr.wr.atomic.rkey);
    + ohdr->u.atomic_eth.swap_data =
    + cpu_to_be64(wqe->wr.wr.atomic.swap);
    + ohdr->u.atomic_eth.compare_data =
    + cpu_to_be64(wqe->wr.wr.atomic.compare_add);
    + hwords += sizeof(struct ib_atomic_eth) / 4;
    + if (newreq) {
    + qp->s_lsn++;
    + wqe->lpsn = wqe->psn;
    + }
    + if (++qp->s_cur == qp->s_size)
    + qp->s_cur = 0;
    + ss = NULL;
    + len = 0;
    + break;
    +
    + default:
    + goto done;
    + }
    + if (newreq) {
    + qp->s_tail++;
    + if (qp->s_tail >= qp->s_size)
    + qp->s_tail = 0;
    + }
    + bth2 |= qp->s_psn++ & IPS_PSN_MASK;
    + if ((int)(qp->s_psn - qp->s_next_psn) > 0)
    + qp->s_next_psn = qp->s_psn;
    + spin_lock(&dev->pending_lock);
    + if (qp->timerwait.next == LIST_POISON1)
    + list_add_tail(&qp->timerwait,
    + &dev->pending[dev->
    + pending_index]);
    + spin_unlock(&dev->pending_lock);
    + break;
    +
    + case IB_OPCODE_RC_RDMA_READ_RESPONSE_FIRST:
    + /*
    + * This case can only happen if a send is
    + * restarted. See ipath_restart_rc().
    + */
    + ipath_init_restart(qp, wqe);
    + /* FALLTHROUGH */
    + case IB_OPCODE_RC_SEND_FIRST:
    + qp->s_state = IB_OPCODE_RC_SEND_MIDDLE;
    + /* FALLTHROUGH */
    + case IB_OPCODE_RC_SEND_MIDDLE:
    + 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;
    + len = qp->s_len;
    + if (len > pmtu) {
    + /*
    + * Request an ACK every 1/2 MB to avoid
    + * retransmit timeouts.
    + */
    + if (((wqe->length - len) %
    + (512 * 1024)) == 0)
    + bth2 |= 1 << 31;
    + len = pmtu;
    + break;
    + }
    + if (wqe->wr.opcode == IB_WR_SEND)
    + qp->s_state = IB_OPCODE_RC_SEND_LAST;
    + else {
    + qp->s_state =
    + IB_OPCODE_RC_SEND_LAST_WITH_IMMEDIATE;
    + /* Immediate data comes after the BTH */
    + ohdr->u.imm_data = wqe->wr.imm_data;
    + hwords += 1;
    + }
    + if (wqe->wr.send_flags & IB_SEND_SOLICITED)
    + bth0 |= 1 << 23;
    + bth2 |= 1 << 31; /* Request ACK. */
    + qp->s_cur++;
    + if (qp->s_cur >= qp->s_size)
    + qp->s_cur = 0;
    + break;
    +
    + case IB_OPCODE_RC_RDMA_READ_RESPONSE_LAST:
    + /*
    + * This case can only happen if a RDMA write is
    + * restarted. See ipath_restart_rc().
    + */
    + ipath_init_restart(qp, wqe);
    + /* FALLTHROUGH */
    + case IB_OPCODE_RC_RDMA_WRITE_FIRST:
    + qp->s_state = IB_OPCODE_RC_RDMA_WRITE_MIDDLE;
    + /* FALLTHROUGH */
    + case IB_OPCODE_RC_RDMA_WRITE_MIDDLE:
    + 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;
    + len = qp->s_len;
    + if (len > pmtu) {
    + /*
    + * Request an ACK every 1/2 MB to avoid
    + * retransmit timeouts.
    + */
    + if (((wqe->length - len) %
    + (512 * 1024)) == 0)
    + bth2 |= 1 << 31;
    + len = pmtu;
    + break;
    + }
    + if (wqe->wr.opcode == IB_WR_RDMA_WRITE)
    + qp->s_state = IB_OPCODE_RC_RDMA_WRITE_LAST;
    + else {
    + qp->s_state =
    + IB_OPCODE_RC_RDMA_WRITE_LAST_WITH_IMMEDIATE;
    + /* Immediate data comes after the BTH */
    + ohdr->u.imm_data = wqe->wr.imm_data;
    + hwords += 1;
    + if (wqe->wr.send_flags & IB_SEND_SOLICITED)
    + bth0 |= 1 << 23;
    + }
    + bth2 |= 1 << 31; /* Request ACK. */
    + qp->s_cur++;
    + if (qp->s_cur >= qp->s_size)
    + qp->s_cur = 0;
    + break;
    +
    + case IB_OPCODE_RC_RDMA_READ_RESPONSE_MIDDLE:
    + /*
    + * This case can only happen if a RDMA read is
    + * restarted. See ipath_restart_rc().
    + */
    + ipath_init_restart(qp, wqe);
    + 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 =
    + cpu_to_be32(wqe->wr.wr.rdma.rkey);
    + ohdr->u.rc.reth.length = cpu_to_be32(qp->s_len);
    + qp->s_state = IB_OPCODE_RC_RDMA_READ_REQUEST;
    + hwords += sizeof(ohdr->u.rc.reth) / 4;
    + 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;
    + len = 0;
    + qp->s_cur++;
    + if (qp->s_cur == qp->s_size)
    + qp->s_cur = 0;
    + break;
    +
    + case IB_OPCODE_RC_RDMA_READ_REQUEST:
    + case IB_OPCODE_RC_COMPARE_SWAP:
    + case IB_OPCODE_RC_FETCH_ADD:
    + /*
    + * We shouldn't start anything new until this
    + * request is finished. The ACK will handle
    + * rescheduling us. XXX The number of outstanding
    + * ones is negotiated at connection setup time (see
    + * pg. 258,289)? XXX Also, if we support multiple
    + * outstanding requests, we need to check the WQE
    + * IB_SEND_FENCE flag and not send a new request if
    + * a RDMA read or atomic is pending.
    + */
    + goto done;
    + }
    + qp->s_len -= len;
    + bth0 |= qp->s_state << 24;
    + /* XXX queue resend timeout. */
    + }
    + /* Make sure it is non-zero before dropping the lock. */
    + qp->s_hdrwords = hwords;
    + spin_unlock_irqrestore(&qp->s_lock, flags);
    +
    + /* Construct the header. */
    + extra_bytes = (4 - len) & 3;
    + nwords = (len + extra_bytes) >> 2;
    + if (unlikely(qp->remote_ah_attr.ah_flags & IB_AH_GRH)) {
    + /* Header size in 32-bit words. */
    + hwords += 10;
    + lrh0 = IPS_LRH_GRH;
    + qp->s_hdr.u.l.grh.version_tclass_flow =
    + cpu_to_be32((6 << 28) |
    + (qp->remote_ah_attr.grh.traffic_class
    + << 20) |
    + qp->remote_ah_attr.grh.flow_label);
    + qp->s_hdr.u.l.grh.paylen =
    + cpu_to_be16(((hwords - 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 =
    + qp->remote_ah_attr.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 = qp->remote_ah_attr.grh.dgid;
    + qp->s_hdrwords = hwords;
    + }
    + qp->s_cur_sge = ss;
    + qp->s_cur_size = len;
    + lrh0 |= qp->remote_ah_attr.sl << 4;
    + qp->s_hdr.lrh[0] = cpu_to_be16(lrh0);
    + /* DEST LID */
    + qp->s_hdr.lrh[1] = cpu_to_be16(qp->remote_ah_attr.dlid);
    + qp->s_hdr.lrh[2] = cpu_to_be16(hwords + nwords + SIZE_OF_CRC);
    + qp->s_hdr.lrh[3] = cpu_to_be16(ipath_layer_get_lid(dev->dd));
    + 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:
    + spin_unlock_irqrestore(&qp->s_lock, flags);
    + clear_bit(IPATH_S_BUSY, &qp->s_flags);
    +}
    +
    +static void send_rc_ack(struct ipath_qp *qp)
    +{
    + struct ipath_ibdev *dev = to_idev(qp->ibqp.device);
    + u16 lrh0;
    + u32 bth0;
    + u32 hwords;
    + 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. */
    + hwords = 6;
    + if (unlikely(qp->remote_ah_attr.ah_flags & IB_AH_GRH)) {
    + ohdr = &qp->s_hdr.u.l.oth;
    + /* Header size in 32-bit words. */
    + hwords += 10;
    + lrh0 = IPS_LRH_GRH;
    + qp->s_hdr.u.l.grh.version_tclass_flow =
    + cpu_to_be32(
    + (6 << 28) |
    + (qp->remote_ah_attr.grh.traffic_class
    + << 20) |
    + qp->remote_ah_attr.grh.flow_label);
    + qp->s_hdr.u.l.grh.paylen =
    + cpu_to_be16(((hwords - 12) + 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 =
    + qp->remote_ah_attr.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 = qp->remote_ah_attr.grh.dgid;
    + }
    + bth0 = ipath_layer_get_pkey(dev->dd, qp->s_pkey_index);
    + ohdr->u.aeth = ipath_compute_aeth(qp);
    + if (qp->s_ack_state >= IB_OPCODE_RC_COMPARE_SWAP) {
    + bth0 |= IB_OPCODE_ATOMIC_ACKNOWLEDGE << 24;
    + ohdr->u.at.atomic_ack_eth = cpu_to_be64(qp->s_ack_atomic);
    + hwords += sizeof(ohdr->u.at.atomic_ack_eth) / 4;
    + }
    + else
    + bth0 |= IB_OPCODE_RC_ACKNOWLEDGE << 24;
    + lrh0 |= qp->remote_ah_attr.sl << 4;
    + qp->s_hdr.lrh[0] = cpu_to_be16(lrh0);
    + /* DEST LID */
    + qp->s_hdr.lrh[1] = cpu_to_be16(qp->remote_ah_attr.dlid);
    + qp->s_hdr.lrh[2] = cpu_to_be16(hwords + 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, hwords, (u32 *) &qp->s_hdr,
    + 0, NULL) == 0) {
    + qp->s_ack_state = IB_OPCODE_RC_ACKNOWLEDGE;
    + dev->n_rc_qacks++;
    + dev->n_unicast_xmit++;
    + }
    +}
    +
    +/**
    + * ipath_restart_rc - back up the requester to resend the last un-ACKed request
    + * @qp: the QP to restart
    + * @psn: packet sequence number for the request
    + * @wc: the work completion request
    + *
    + * 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.
    + */
    + if (ipath_cmp24(psn, qp->s_next_psn) >= 0 ||
    + qp->s_last == qp->s_tail)
    + goto done;
    +
    + if (qp->s_retry == 0) {
    + wc->wr_id = wqe->wr.wr_id;
    + wc->status = IB_WC_RETRY_EXC_ERR;
    + wc->opcode = ib_ipath_wc_opcode[wqe->wr.opcode];
    + wc->vendor_err = 0;
    + wc->byte_len = 0;
    + wc->qp_num = qp->ibqp.qp_num;
    + wc->src_qp = qp->remote_qpn;
    + wc->pkey_index = 0;
    + wc->slid = qp->remote_ah_attr.dlid;
    + wc->sl = qp->remote_ah_attr.sl;
    + wc->dlid_path_bits = 0;
    + wc->port_num = 0;
    + ipath_sqerror_qp(qp, wc);
    + return;
    + }
    + qp->s_retry--;
    +
    + /*
    + * Remove the QP from the timeout queue.
    + * Note: it may already have been removed by ipath_ib_timer().
    + */
    + dev = to_idev(qp->ibqp.device);
    + spin_lock(&dev->pending_lock);
    + if (qp->timerwait.next != LIST_POISON1)
    + list_del(&qp->timerwait);
    + spin_unlock(&dev->pending_lock);
    +
    + if (wqe->wr.opcode == IB_WR_RDMA_READ)
    + dev->n_rc_resends++;
    + else
    + dev->n_rc_resends += (int)qp->s_psn - (int)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 = IB_OPCODE_RC_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 = IB_OPCODE_RC_RDMA_READ_RESPONSE_FIRST;
    + break;
    +
    + case IB_WR_RDMA_WRITE:
    + case IB_WR_RDMA_WRITE_WITH_IMM:
    + qp->s_state = IB_OPCODE_RC_RDMA_READ_RESPONSE_LAST;
    + break;
    +
    + case IB_WR_RDMA_READ:
    + qp->s_state =
    + IB_OPCODE_RC_RDMA_READ_RESPONSE_MIDDLE;
    + break;
    +
    + default:
    + /*
    + * This case shouldn't happen since its only
    + * one PSN per req.
    + */
    + qp->s_state = IB_OPCODE_RC_SEND_LAST;
    + }
    + }
    +
    +done:
    + tasklet_hi_schedule(&qp->s_task);
    +}
    +
    +/**
    + * 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() to process an incoming RC ACK
    + * for the given QP.
    + * 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)
    +{
    + struct ipath_ibdev *dev = to_idev(qp->ibqp.device);
    + struct ib_wc wc;
    + struct ipath_swqe *wqe;
    +
    + /*
    + * Remove the QP from the timeout queue (or RNR timeout queue).
    + * If ipath_ib_timer() has already removed it,
    + * it's OK since we hold the QP s_lock and ipath_restart_rc()
    + * just won't find anything to restart if we ACK everything.
    + */
    + spin_lock(&dev->pending_lock);
    + if (qp->timerwait.next != LIST_POISON1)
    + list_del(&qp->timerwait);
    + spin_unlock(&dev->pending_lock);
    +
    + /*
    + * Note that NAKs implicitly ACK outstanding SEND and
    + * RDMA write requests and implicitly NAK RDMA read and
    + * atomic requests issued before the NAK'ed request.
    + * The MSN won't include the NAK'ed request but will include
    + * an ACK'ed request(s).
    + */
    + wqe = get_swqe_ptr(qp, qp->s_last);
    +
    + /* Nothing is pending to ACK/NAK. */
    + if (qp->s_last == qp->s_tail)
    + return 0;
    +
    + /*
    + * The MSN might be for a later WQE than the PSN indicates so
    + * only complete WQEs that the PSN finishes.
    + */
    + while (ipath_cmp24(psn, wqe->lpsn) >= 0) {
    + /* If we are ACKing a WQE, the MSN should be >= the SSN. */
    + if (ipath_cmp24(aeth, wqe->ssn) < 0)
    + break;
    + /*
    + * If this request is a RDMA read or atomic, and the ACK is
    + * for a later operation, this ACK NAKs the RDMA read or
    + * atomic. In other words, only a RDMA_READ_LAST or ONLY
    + * can ACK a RDMA read and likewise for atomic ops. Note
    + * that the NAK case can only happen if relaxed ordering is
    + * used and requests are sent after an RDMA read or atomic
    + * is sent but before the response is received.
    + */
    + if ((wqe->wr.opcode == IB_WR_RDMA_READ &&
    + opcode != IB_OPCODE_RC_RDMA_READ_RESPONSE_LAST) ||
    + ((wqe->wr.opcode == IB_WR_ATOMIC_CMP_AND_SWP ||
    + wqe->wr.opcode == IB_WR_ATOMIC_FETCH_AND_ADD) &&
    + (opcode != IB_OPCODE_RC_ATOMIC_ACKNOWLEDGE ||
    + ipath_cmp24(wqe->psn, psn) != 0))) {
    + /*
    + * The last valid PSN seen is the previous
    + * request's.
    + */
    + qp->s_last_psn = wqe->psn - 1;
    + /* Retry this request. */
    + ipath_restart_rc(qp, wqe->psn, &wc);
    + /*
    + * No need to process the ACK/NAK since we are
    + * restarting an earlier request.
    + */
    + return 0;
    + }
    + /* Post a send completion queue entry if requested. */
    + if (!test_bit(IPATH_S_SIGNAL_REQ_WR, &qp->s_flags) ||
    + (wqe->wr.send_flags & IB_SEND_SIGNALED)) {
    + wc.wr_id = wqe->wr.wr_id;
    + wc.status = IB_WC_SUCCESS;
    + wc.opcode = ib_ipath_wc_opcode[wqe->wr.opcode];
    + wc.vendor_err = 0;
    + wc.byte_len = wqe->length;
    + wc.qp_num = qp->ibqp.qp_num;
    + wc.src_qp = qp->remote_qpn;
    + wc.pkey_index = 0;
    + wc.slid = qp->remote_ah_attr.dlid;
    + wc.sl = qp->remote_ah_attr.sl;
    + wc.dlid_path_bits = 0;
    + wc.port_num = 0;
    + ipath_cq_enter(to_icq(qp->ibqp.send_cq), &wc, 0);
    + }
    + qp->s_retry = qp->s_retry_cnt;
    + /*
    + * If we are completing a request which is in the process
    + * of being resent, we can stop resending it since we know
    + * the responder has already seen it.
    + */
    + if (qp->s_last == qp->s_cur) {
    + if (++qp->s_cur >= qp->s_size)
    + qp->s_cur = 0;
    + wqe = get_swqe_ptr(qp, qp->s_cur);
    + qp->s_state = IB_OPCODE_RC_SEND_LAST;
    + qp->s_psn = wqe->psn;
    + }
    + if (++qp->s_last >= qp->s_size)
    + qp->s_last = 0;
    + wqe = get_swqe_ptr(qp, qp->s_last);
    + if (qp->s_last == qp->s_tail)
    + break;
    + }
    +
    + switch (aeth >> 29) {
    + case 0: /* ACK */
    + dev->n_rc_acks++;
    + /* If this is a partial ACK, reset the retransmit timer. */
    + if (qp->s_last != qp->s_tail) {
    + spin_lock(&dev->pending_lock);
    + list_add_tail(&qp->timerwait,
    + &dev->pending[dev->pending_index]);
    + spin_unlock(&dev->pending_lock);
    + }
    + ipath_get_credit(qp, aeth);
    + qp->s_rnr_retry = qp->s_rnr_retry_cnt;
    + qp->s_retry = qp->s_retry_cnt;
    + qp->s_last_psn = psn;
    + return 1;
    +
    + case 1: /* RNR NAK */
    + dev->n_rnr_naks++;
    + if (qp->s_rnr_retry == 0) {
    + if (qp->s_last == qp->s_tail)
    + return 0;
    +
    + wc.status = IB_WC_RNR_RETRY_EXC_ERR;
    + goto class_b;
    + }
    + if (qp->s_rnr_retry_cnt < 7)
    + qp->s_rnr_retry--;
    + if (qp->s_last == qp->s_tail)
    + return 0;
    +
    + /* The last valid PSN seen is the previous request's. */
    + qp->s_last_psn = wqe->psn - 1;
    +
    + /* Restart this request after the RNR timeout. */
    + wqe = get_swqe_ptr(qp, qp->s_last);
    +
    + dev->n_rc_resends += (int)qp->s_psn - (int)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 = IB_OPCODE_RC_SEND_LAST;
    + qp->s_psn = wqe->psn;
    + } else {
    + u32 n;
    +
    + 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;
    +
    + /*
    + * 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 =
    + IB_OPCODE_RC_RDMA_READ_RESPONSE_FIRST;
    + break;
    +
    + case IB_WR_RDMA_WRITE:
    + case IB_WR_RDMA_WRITE_WITH_IMM:
    + qp->s_state =
    + IB_OPCODE_RC_RDMA_READ_RESPONSE_LAST;
    + break;
    +
    + case IB_WR_RDMA_READ:
    + qp->s_state =
    + IB_OPCODE_RC_RDMA_READ_RESPONSE_MIDDLE;
    + break;
    +
    + default:
    + /*
    + * This case shouldn't happen since its only
    + * one PSN per req.
    + */
    + qp->s_state = IB_OPCODE_RC_SEND_LAST;
    + }
    + }
    +
    + qp->s_rnr_timeout =
    + ib_ipath_rnr_table[(aeth >> IPS_AETH_CREDIT_SHIFT) &
    + IPS_AETH_CREDIT_MASK];
    + ipath_insert_rnr_queue(qp);
    + return 0;
    +
    + case 3: /* NAK */
    + /* 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 >> IPS_AETH_CREDIT_SHIFT) &
    + IPS_AETH_CREDIT_MASK) {
    + case 0: /* PSN sequence error */
    + dev->n_seq_naks++;
    + /*
    + * Back up to the responder's expected PSN.
    + * XXX Note that we might get a NAK in the
    + * middle of an RDMA READ response which
    + * terminates the RDMA READ.
    + */
    + if (qp->s_last == qp->s_tail)
    + break;
    +
    + if (ipath_cmp24(psn, wqe->psn) < 0)
    + break;
    +
    + /* Retry the request. */
    + ipath_restart_rc(qp, psn, &wc);
    + break;
    +
    + case 1: /* Invalid Request */
    + wc.status = IB_WC_REM_INV_REQ_ERR;
    + dev->n_other_naks++;
    + goto class_b;
    +
    + case 2: /* Remote Access Error */
    + wc.status = IB_WC_REM_ACCESS_ERR;
    + dev->n_other_naks++;
    + goto class_b;
    +
    + case 3: /* Remote Operation Error */
    + wc.status = IB_WC_REM_OP_ERR;
    + dev->n_other_naks++;
    + class_b:
    + wc.wr_id = wqe->wr.wr_id;
    + wc.opcode = ib_ipath_wc_opcode[wqe->wr.opcode];
    + wc.vendor_err = 0;
    + wc.byte_len = 0;
    + wc.qp_num = qp->ibqp.qp_num;
    + wc.src_qp = qp->remote_qpn;
    + wc.pkey_index = 0;
    + wc.slid = qp->remote_ah_attr.dlid;
    + wc.sl = qp->remote_ah_attr.sl;
    + wc.dlid_path_bits = 0;
    + wc.port_num = 0;
    + ipath_sqerror_qp(qp, &wc);
    + break;
    +
    + default:
    + /* Ignore other reserved NAK error codes */
    + goto reserved;
    + }
    + qp->s_rnr_retry = qp->s_rnr_retry_cnt;
    + return 0;
    +
    + default: /* 2: reserved */
    + reserved:
    + /* Ignore reserved NAK codes. */
    + return 0;
    + }
    +}
    +
    +/**
    + * ipath_rc_rcv - process an incoming RC packet
    + * @dev: the device this packet came in on
    + * @hdr: the header of this packet
    + * @has_grh: true if the header has a GRH
    + * @data: the packet data
    + * @tlen: the packet length
    + * @qp: the QP for this packet
    + *
    + * This is called from ipath_qp_rcv() to process an incoming RC packet
    + * for the given QP.
    + * Called at interrupt level.
    + */
    +void ipath_rc_rcv(struct ipath_ibdev *dev, struct ipath_ib_header *hdr,
    + int has_grh, void *data, u32 tlen, struct ipath_qp *qp)
    +{
    + struct ipath_other_headers *ohdr;
    + int opcode;
    + 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;
    + struct ib_reth *reth;
    +
    + /* Check for GRH */
    + if (!has_grh) {
    + ohdr = &hdr->u.oth;
    + hdrsize = 8 + 12; /* LRH + BTH */
    + psn = be32_to_cpu(ohdr->bth[2]);
    + } else {
    + ohdr = &hdr->u.l.oth;
    + hdrsize = 8 + 40 + 12; /* LRH + GRH + BTH */
    + /*
    + * The header with GRH is 60 bytes and the
    + * core driver sets the eager header buffer
    + * size to 56 bytes so the last 4 bytes of
    + * the BTH header (PSN) is in the data buffer.
    + */
    + psn = be32_to_cpu(((u32 *) data)[0]);
    + data += sizeof(u32);
    + }
    + /*
    + * 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 packet sequence number will be for something
    + * in the send work queue rather than the expected receive
    + * packet sequence number. In other words, this QP is the
    + * requester.
    + */
    + if (opcode >= IB_OPCODE_RC_RDMA_READ_RESPONSE_FIRST &&
    + opcode <= IB_OPCODE_RC_ATOMIC_ACKNOWLEDGE) {
    +
    + spin_lock_irqsave(&qp->s_lock, flags);
    +
    + /* Ignore invalid responses. */
    + if (ipath_cmp24(psn, qp->s_next_psn) >= 0)
    + goto ack_done;
    +
    + /* Ignore duplicate responses. */
    + diff = ipath_cmp24(psn, qp->s_last_psn);
    + if (unlikely(diff <= 0)) {
    + /* Update credits for "ghost" ACKs */
    + if (diff == 0 &&
    + opcode == IB_OPCODE_RC_ACKNOWLEDGE) {
    + if (!has_grh) {
    + pad = be32_to_cpu(ohdr->u.aeth);
    + } else {
    + pad = be32_to_cpu(
    + ((u32 *) data)[0]);
    + data += sizeof(u32);
    + }
    + if ((pad >> 29) == 0)
    + ipath_get_credit(qp, pad);
    + }
    + goto ack_done;
    + }
    +
    + switch (opcode) {
    + case IB_OPCODE_RC_ACKNOWLEDGE:
    + case IB_OPCODE_RC_ATOMIC_ACKNOWLEDGE:
    + case IB_OPCODE_RC_RDMA_READ_RESPONSE_FIRST:
    + if (!has_grh)
    + pad = be32_to_cpu(ohdr->u.aeth);
    + else {
    + pad = be32_to_cpu(((u32 *) data)[0]);
    + data += sizeof(u32);
    + }
    + if (opcode == IB_OPCODE_RC_ATOMIC_ACKNOWLEDGE)
    + *(u64 *) qp->s_sge.sge.vaddr =
    + *(u64 *) data;
    + if (!do_rc_ack(qp, pad, psn, opcode) ||
    + opcode != IB_OPCODE_RC_RDMA_READ_RESPONSE_FIRST)
    + goto ack_done;
    + hdrsize += 4;
    + /*
    + * do_rc_ack() has already checked the PSN so skip
    + * the sequence check.
    + */
    + goto rdma_read;
    +
    + case IB_OPCODE_RC_RDMA_READ_RESPONSE_MIDDLE:
    + /* no AETH, no ACK */
    + if (unlikely(ipath_cmp24(psn,
    + qp->s_last_psn + 1))) {
    + dev->n_rdma_seq++;
    + ipath_restart_rc(qp, qp->s_last_psn + 1,
    + &wc);
    + goto ack_done;
    + }
    + rdma_read:
    + if (unlikely(qp->s_state !=
    + IB_OPCODE_RC_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 &&
    + qp->timerwait.next != LIST_POISON1) {
    + 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);
    + return;
    +
    + case IB_OPCODE_RC_RDMA_READ_RESPONSE_LAST:
    + /* ACKs READ req. */
    + if (unlikely(ipath_cmp24(psn,
    + qp->s_last_psn + 1))) {
    + dev->n_rdma_seq++;
    + ipath_restart_rc(qp, qp->s_last_psn + 1,
    + &wc);
    + goto ack_done;
    + }
    + /* FALLTHROUGH */
    + case IB_OPCODE_RC_RDMA_READ_RESPONSE_ONLY:
    + if (unlikely(qp->s_state !=
    + IB_OPCODE_RC_RDMA_READ_REQUEST))
    + goto ack_done;
    + /*
    + * Get the number of bytes the message was padded
    + * by.
    + */
    + pad = (be32_to_cpu(ohdr->bth[0]) >> 20) & 3;
    + /*
    + * Check that the data size is >= 1 && <= pmtu.
    + * Remember to account for the AETH header (4) and
    + * ICRC (4).
    + */
    + if (unlikely(tlen <= (hdrsize + pad + 8))) {
    + /*
    + * 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.
    + */
    + goto ack_done;
    + }
    + if (!has_grh) {
    + pad = be32_to_cpu(ohdr->u.aeth);
    + } else {
    + pad = be32_to_cpu(((u32 *) data)[0]);
    + data += sizeof(u32);
    + }
    + ipath_copy_sge(&qp->s_sge, data, tlen);
    + if (do_rc_ack(
    + qp, pad, psn,
    + IB_OPCODE_RC_RDMA_READ_RESPONSE_LAST)) {
    + /*
    + * Change the state so we contimue
    + * processing new requests.
    + */
    + qp->s_state = IB_OPCODE_RC_SEND_LAST;
    + }
    + goto ack_done;
    + }
    + ack_done:
    + spin_unlock_irqrestore(&qp->s_lock, flags);
    + return;
    + }
    +
    + 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 (diff > 0) {
    + /*
    + * Packet sequence error.
    + * 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 >=
    + IB_OPCODE_RC_RDMA_READ_REQUEST &&
    + qp->s_ack_state != IB_OPCODE_ACKNOWLEDGE) ||
    + qp->s_nak_state != 0) {
    + spin_unlock(&qp->s_lock);
    + goto done;
    + }
    + qp->s_ack_state = IB_OPCODE_RC_SEND_ONLY;
    + qp->s_nak_state = IB_NAK_PSN_ERROR;
    + /* Use the expected PSN. */
    + qp->s_ack_psn = qp->r_psn;
    + goto resched;
    + }
    +
    + /*
    + * Handle a duplicate request. Don't re-execute SEND, RDMA
    + * write or atomic op. Don't NAK errors, just silently drop
    + * the duplicate request. Note that r_sge, r_len, and
    + * r_rcv_len may be in use so don't modify them.
    + *
    + * We are supposed to ACK the earliest duplicate PSN but we
    + * can coalesce an outstanding duplicate ACK. We have to
    + * send the earliest so that RDMA reads can be restarted at
    + * the requester's expected PSN.
    + */
    + 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 IB_OPCODE_RC_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 != IB_OPCODE_RC_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 (!has_grh)
    + reth = &ohdr->u.rc.reth;
    + else {
    + reth = (struct ib_reth *)data;
    + data += sizeof(*reth);
    + }
    + qp->s_rdma_len = be32_to_cpu(reth->length);
    + if (qp->s_rdma_len != 0) {
    + u32 rkey = be32_to_cpu(reth->rkey);
    + u64 vaddr = be64_to_cpu(reth->vaddr);
    +
    + /*
    + * Address range must be a subset of the
    + * original request and start on pmtu
    + * boundaries.
    + */
    + if (unlikely(!ipath_rkey_ok(dev,
    + &qp->s_rdma_sge,
    + qp->s_rdma_len,
    + vaddr, rkey,
    + IB_ACCESS_REMOTE_READ)))
    + goto done;
    + } else {
    + qp->s_rdma_sge.sg_list = NULL;
    + qp->s_rdma_sge.num_sge = 0;
    + qp->s_rdma_sge.sge.mr = NULL;
    + qp->s_rdma_sge.sge.vaddr = NULL;
    + qp->s_rdma_sge.sge.length = 0;
    + qp->s_rdma_sge.sge.sge_length = 0;
    + }
    + break;
    +
    + case IB_OPCODE_RC_COMPARE_SWAP:
    + case IB_OPCODE_RC_FETCH_ADD:
    + /*
    + * Check for the PSN of the last atomic operations
    + * performed and resend the result if found.
    + */
    + 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->s_ack_state = opcode;
    + qp->s_nak_state = 0;
    + qp->s_ack_psn = psn;
    + goto resched;
    + }
    +
    + /* Check for opcode sequence errors. */
    + switch (qp->r_state) {
    + case IB_OPCODE_RC_SEND_FIRST:
    + case IB_OPCODE_RC_SEND_MIDDLE:
    + if (opcode == IB_OPCODE_RC_SEND_MIDDLE ||
    + opcode == IB_OPCODE_RC_SEND_LAST ||
    + opcode == IB_OPCODE_RC_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.
    + */
    + spin_lock(&qp->s_lock);
    + if (qp->s_ack_state >= IB_OPCODE_RC_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 = IB_OPCODE_RC_SEND_ONLY;
    + qp->s_nak_state = IB_NAK_INVALID_REQUEST;
    + qp->s_ack_psn = qp->r_psn;
    + goto resched;
    +
    + case IB_OPCODE_RC_RDMA_WRITE_FIRST:
    + case IB_OPCODE_RC_RDMA_WRITE_MIDDLE:
    + if (opcode == IB_OPCODE_RC_RDMA_WRITE_MIDDLE ||
    + opcode == IB_OPCODE_RC_RDMA_WRITE_LAST ||
    + opcode == IB_OPCODE_RC_RDMA_WRITE_LAST_WITH_IMMEDIATE)
    + break;
    + goto nack_inv;
    +
    + case IB_OPCODE_RC_RDMA_READ_REQUEST:
    + case IB_OPCODE_RC_COMPARE_SWAP:
    + case IB_OPCODE_RC_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 == IB_OPCODE_RC_SEND_MIDDLE ||
    + opcode == IB_OPCODE_RC_SEND_LAST ||
    + opcode == IB_OPCODE_RC_SEND_LAST_WITH_IMMEDIATE ||
    + opcode == IB_OPCODE_RC_RDMA_WRITE_MIDDLE ||
    + opcode == IB_OPCODE_RC_RDMA_WRITE_LAST ||
    + opcode == IB_OPCODE_RC_RDMA_WRITE_LAST_WITH_IMMEDIATE)
    + goto nack_inv;
    + break;
    + }
    +
    + wc.imm_data = 0;
    + wc.wc_flags = 0;
    +
    + /* OK, process the packet. */
    + switch (opcode) {
    + case IB_OPCODE_RC_SEND_FIRST:
    + if (!ipath_get_rwqe(qp, 0)) {
    + rnr_nak:
    + /*
    + * A RNR NAK will ACK earlier sends and RDMA writes.
    + * Don't queue the NAK if a RDMA read or atomic
    + * is pending though.
    + */
    + spin_lock(&qp->s_lock);
    + if (qp->s_ack_state >=
    + IB_OPCODE_RC_RDMA_READ_REQUEST &&
    + qp->s_ack_state != IB_OPCODE_ACKNOWLEDGE) {
    + spin_unlock(&qp->s_lock);
    + goto done;
    + }
    + qp->s_ack_state = IB_OPCODE_RC_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 */
    + case IB_OPCODE_RC_SEND_MIDDLE:
    + case IB_OPCODE_RC_RDMA_WRITE_MIDDLE:
    + send_middle:
    + /* Check for invalid length PMTU or posted rwqe len. */
    + if (unlikely(tlen != (hdrsize + pmtu + 4)))
    + goto nack_inv;
    + qp->r_rcv_len += pmtu;
    + if (unlikely(qp->r_rcv_len > qp->r_len))
    + goto nack_inv;
    + ipath_copy_sge(&qp->r_sge, data, pmtu);
    + break;
    +
    + case IB_OPCODE_RC_RDMA_WRITE_LAST_WITH_IMMEDIATE:
    + /* consume RWQE */
    + if (!ipath_get_rwqe(qp, 1))
    + goto rnr_nak;
    + goto send_last_imm;
    +
    + case IB_OPCODE_RC_SEND_ONLY:
    + case IB_OPCODE_RC_SEND_ONLY_WITH_IMMEDIATE:
    + if (!ipath_get_rwqe(qp, 0))
    + goto rnr_nak;
    + qp->r_rcv_len = 0;
    + if (opcode == IB_OPCODE_RC_SEND_ONLY)
    + goto send_last;
    + /* FALLTHROUGH */
    + case IB_OPCODE_RC_SEND_LAST_WITH_IMMEDIATE:
    + send_last_imm:
    + if (has_grh) {
    + wc.imm_data = *(u32 *) data;
    + data += sizeof(u32);
    + } else {
    + /* Immediate data comes after BTH */
    + wc.imm_data = ohdr->u.imm_data;
    + }
    + hdrsize += 4;
    + wc.wc_flags = IB_WC_WITH_IMM;
    + /* FALLTHROUGH */
    + case IB_OPCODE_RC_SEND_LAST:
    + case IB_OPCODE_RC_RDMA_WRITE_LAST:
    + send_last:
    + /* Get the number of bytes the message was padded by. */
    + pad = (be32_to_cpu(ohdr->bth[0]) >> 20) & 3;
    + /* Check for invalid length. */
    + /* XXX LAST len should be >= 1 */
    + if (unlikely(tlen < (hdrsize + pad + 4)))
    + goto nack_inv;
    + /* Don't count the CRC. */
    + tlen -= (hdrsize + pad + 4);
    + wc.byte_len = tlen + qp->r_rcv_len;
    + if (unlikely(wc.byte_len > qp->r_len)) {
    + goto nack_inv;
    + }
    + /* XXX Need to free SGEs */
    + ipath_copy_sge(&qp->r_sge, data, tlen);
    + atomic_inc(&qp->msn);
    + if (opcode == IB_OPCODE_RC_RDMA_WRITE_LAST ||
    + opcode == IB_OPCODE_RC_RDMA_WRITE_ONLY)
    + break;
    + wc.wr_id = qp->r_wr_id;
    + wc.status = IB_WC_SUCCESS;
    + wc.opcode = IB_WC_RECV;
    + wc.vendor_err = 0;
    + wc.qp_num = qp->ibqp.qp_num;
    + wc.src_qp = qp->remote_qpn;
    + wc.pkey_index = 0;
    + wc.slid = qp->remote_ah_attr.dlid;
    + wc.sl = qp->remote_ah_attr.sl;
    + wc.dlid_path_bits = 0;
    + wc.port_num = 0;
    + /* Signal completion event if the solicited bit is set. */
    + ipath_cq_enter(to_icq(qp->ibqp.recv_cq), &wc,
    + ohdr->bth[0] &
    + __constant_cpu_to_be32(1 << 23));
    + break;
    +
    + case IB_OPCODE_RC_RDMA_WRITE_FIRST:
    + case IB_OPCODE_RC_RDMA_WRITE_ONLY:
    + case IB_OPCODE_RC_RDMA_WRITE_ONLY_WITH_IMMEDIATE:
    + /* consume RWQE */
    + /* RETH comes after BTH */
    + if (!has_grh)
    + reth = &ohdr->u.rc.reth;
    + else {
    + reth = (struct ib_reth *)data;
    + data += sizeof(*reth);
    + }
    + hdrsize += sizeof(*reth);
    + qp->r_len = be32_to_cpu(reth->length);
    + qp->r_rcv_len = 0;
    + if (qp->r_len != 0) {
    + u32 rkey = be32_to_cpu(reth->rkey);
    + u64 vaddr = be64_to_cpu(reth->vaddr);
    +
    + /* Check rkey & NAK */
    + if (unlikely(!ipath_rkey_ok(dev, &qp->r_sge,
    + qp->r_len,
    + vaddr, rkey,
    + IB_ACCESS_REMOTE_WRITE))) {
    + 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 >=
    + IB_OPCODE_RC_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 = IB_OPCODE_RC_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;
    + qp->r_sge.sge.vaddr = NULL;
    + qp->r_sge.sge.length = 0;
    + qp->r_sge.sge.sge_length = 0;
    + }
    + if (unlikely(!(qp->qp_access_flags &
    + IB_ACCESS_REMOTE_WRITE)))
    + goto nack_acc;
    + if (opcode == IB_OPCODE_RC_RDMA_WRITE_FIRST)
    + goto send_middle;
    + else if (opcode == IB_OPCODE_RC_RDMA_WRITE_ONLY)
    + goto send_last;
    + if (!ipath_get_rwqe(qp, 1))
    + goto rnr_nak;
    + goto send_last_imm;
    +
    + case IB_OPCODE_RC_RDMA_READ_REQUEST:
    + /* RETH comes after BTH */
    + if (!has_grh)
    + reth = &ohdr->u.rc.reth;
    + else {
    + reth = (struct ib_reth *)data;
    + data += sizeof(*reth);
    + }
    + spin_lock(&qp->s_lock);
    + if (qp->s_ack_state != IB_OPCODE_RC_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);
    + u64 vaddr = be64_to_cpu(reth->vaddr);
    +
    + /* Check rkey & NAK */
    + if (unlikely(!ipath_rkey_ok(
    + dev, &qp->s_rdma_sge,
    + qp->s_rdma_len,
    + vaddr, rkey,
    + IB_ACCESS_REMOTE_READ))) {
    + spin_unlock(&qp->s_lock);
    + goto nack_acc;
    + }
    + /*
    + * Update the next expected PSN. We add 1 later
    + * below, so only add the remainder here.
    + */
    + if (qp->s_rdma_len > pmtu)
    + qp->r_psn += (qp->s_rdma_len - 1) / pmtu;
    + } else {
    + qp->s_rdma_sge.sg_list = NULL;
    + qp->s_rdma_sge.num_sge = 0;
    + qp->s_rdma_sge.sge.mr = NULL;
    + qp->s_rdma_sge.sge.vaddr = NULL;
    + 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.
    + */
    + atomic_inc(&qp->msn);
    + qp->s_ack_state = opcode;
    + qp->s_nak_state = 0;
    + qp->s_ack_psn = psn;
    + qp->r_psn++;
    + qp->r_state = opcode;
    + goto rdmadone;
    +
    + case IB_OPCODE_RC_COMPARE_SWAP:
    + case IB_OPCODE_RC_FETCH_ADD:{
    + struct ib_atomic_eth *ateth;
    + u64 vaddr;
    + u64 sdata;
    + u32 rkey;
    +
    + if (!has_grh)
    + ateth = &ohdr->u.atomic_eth;
    + else {
    + ateth = (struct ib_atomic_eth *)data;
    + data += sizeof(*ateth);
    + }
    + vaddr = be64_to_cpu(ateth->vaddr);
    + if (unlikely(vaddr & (sizeof(u64) - 1)))
    + goto nack_inv;
    + rkey = be32_to_cpu(ateth->rkey);
    + /* Check rkey & NAK */
    + if (unlikely(!ipath_rkey_ok(dev, &qp->r_sge,
    + sizeof(u64), vaddr, rkey,
    + IB_ACCESS_REMOTE_ATOMIC)))
    + goto nack_acc;
    + if (unlikely(!(qp->qp_access_flags &
    + IB_ACCESS_REMOTE_ATOMIC)))
    + goto nack_acc;
    + /* Perform atomic OP and save result. */
    + sdata = be64_to_cpu(ateth->swap_data);
    + spin_lock(&dev->pending_lock);
    + qp->r_atomic_data = *(u64 *) qp->r_sge.sge.vaddr;
    + if (opcode == IB_OPCODE_RC_FETCH_ADD)
    + *(u64 *) qp->r_sge.sge.vaddr =
    + qp->r_atomic_data + sdata;
    + else if (qp->r_atomic_data ==
    + be64_to_cpu(ateth->compare_data))
    + *(u64 *) qp->r_sge.sge.vaddr = sdata;
    + spin_unlock(&dev->pending_lock);
    + atomic_inc(&qp->msn);
    + qp->r_atomic_psn = psn & IPS_PSN_MASK;
    + psn |= 1 << 31;
    + break;
    + }
    +
    + default:
    + /* Drop packet for unknown opcodes. */
    + spin_unlock_irqrestore(&qp->r_rq.lock, flags);
    + return;
    + }
    + qp->r_psn++;
    + qp->r_state = opcode;
    + /* Send an ACK if requested or required. */
    + if (psn & (1 << 31)) {
    + /*
    + * Coalesce ACKs unless there is a RDMA READ or
    + * ATOMIC pending.
    + */
    + spin_lock(&qp->s_lock);
    + if (qp->s_ack_state == IB_OPCODE_RC_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;
    + }
    + spin_unlock(&qp->s_lock);
    + }
    +done:
    + spin_unlock_irqrestore(&qp->r_rq.lock, flags);
    + return;
    +
    +resched:
    + /*
    + * Try to send ACK right away but not if ipath_do_rc_send() is
    + * active.
    + */
    + 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);
    +
    +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);
    +}
    -
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