blob: f8a7de795beb6cec734860018e375d19a4bf2bd7 [file] [log] [blame]
/*
* Copyright (c) 2006, 2007, 2008, 2009 QLogic Corporation. 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
* licenses. You may choose to be licensed under the terms of the GNU
* General Public License (GPL) Version 2, available from the file
* COPYING in the main directory of this source tree, or the
* OpenIB.org BSD license below:
*
* Redistribution and use in source and binary forms, with or
* without modification, are permitted provided that the following
* conditions are met:
*
* - Redistributions of source code must retain the above
* copyright notice, this list of conditions and the following
* disclaimer.
*
* - Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following
* disclaimer in the documentation and/or other materials
* provided with the distribution.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
#include <linux/spinlock.h>
#include <rdma/ib_smi.h>
#include "qib.h"
#include "qib_mad.h"
/*
* Switch to alternate path.
* The QP s_lock should be held and interrupts disabled.
*/
void qib_migrate_qp(struct rvt_qp *qp)
{
struct ib_event ev;
qp->s_mig_state = IB_MIG_MIGRATED;
qp->remote_ah_attr = qp->alt_ah_attr;
qp->port_num = rdma_ah_get_port_num(&qp->alt_ah_attr);
qp->s_pkey_index = qp->s_alt_pkey_index;
ev.device = qp->ibqp.device;
ev.element.qp = &qp->ibqp;
ev.event = IB_EVENT_PATH_MIG;
qp->ibqp.event_handler(&ev, qp->ibqp.qp_context);
}
static __be64 get_sguid(struct qib_ibport *ibp, unsigned index)
{
if (!index) {
struct qib_pportdata *ppd = ppd_from_ibp(ibp);
return ppd->guid;
}
return ibp->guids[index - 1];
}
static int gid_ok(union ib_gid *gid, __be64 gid_prefix, __be64 id)
{
return (gid->global.interface_id == id &&
(gid->global.subnet_prefix == gid_prefix ||
gid->global.subnet_prefix == IB_DEFAULT_GID_PREFIX));
}
/*
*
* This should be called with the QP r_lock held.
*
* The s_lock will be acquired around the qib_migrate_qp() call.
*/
int qib_ruc_check_hdr(struct qib_ibport *ibp, struct ib_header *hdr,
int has_grh, struct rvt_qp *qp, u32 bth0)
{
__be64 guid;
unsigned long flags;
if (qp->s_mig_state == IB_MIG_ARMED && (bth0 & IB_BTH_MIG_REQ)) {
if (!has_grh) {
if (rdma_ah_get_ah_flags(&qp->alt_ah_attr) &
IB_AH_GRH)
goto err;
} else {
const struct ib_global_route *grh;
if (!(rdma_ah_get_ah_flags(&qp->alt_ah_attr) &
IB_AH_GRH))
goto err;
grh = rdma_ah_read_grh(&qp->alt_ah_attr);
guid = get_sguid(ibp, grh->sgid_index);
if (!gid_ok(&hdr->u.l.grh.dgid,
ibp->rvp.gid_prefix, guid))
goto err;
if (!gid_ok(&hdr->u.l.grh.sgid,
grh->dgid.global.subnet_prefix,
grh->dgid.global.interface_id))
goto err;
}
if (!qib_pkey_ok((u16)bth0,
qib_get_pkey(ibp, qp->s_alt_pkey_index))) {
qib_bad_pkey(ibp,
(u16)bth0,
(be16_to_cpu(hdr->lrh[0]) >> 4) & 0xF,
0, qp->ibqp.qp_num,
hdr->lrh[3], hdr->lrh[1]);
goto err;
}
/* Validate the SLID. See Ch. 9.6.1.5 and 17.2.8 */
if ((be16_to_cpu(hdr->lrh[3]) !=
rdma_ah_get_dlid(&qp->alt_ah_attr)) ||
ppd_from_ibp(ibp)->port !=
rdma_ah_get_port_num(&qp->alt_ah_attr))
goto err;
spin_lock_irqsave(&qp->s_lock, flags);
qib_migrate_qp(qp);
spin_unlock_irqrestore(&qp->s_lock, flags);
} else {
if (!has_grh) {
if (rdma_ah_get_ah_flags(&qp->remote_ah_attr) &
IB_AH_GRH)
goto err;
} else {
const struct ib_global_route *grh;
if (!(rdma_ah_get_ah_flags(&qp->remote_ah_attr) &
IB_AH_GRH))
goto err;
grh = rdma_ah_read_grh(&qp->remote_ah_attr);
guid = get_sguid(ibp, grh->sgid_index);
if (!gid_ok(&hdr->u.l.grh.dgid,
ibp->rvp.gid_prefix, guid))
goto err;
if (!gid_ok(&hdr->u.l.grh.sgid,
grh->dgid.global.subnet_prefix,
grh->dgid.global.interface_id))
goto err;
}
if (!qib_pkey_ok((u16)bth0,
qib_get_pkey(ibp, qp->s_pkey_index))) {
qib_bad_pkey(ibp,
(u16)bth0,
(be16_to_cpu(hdr->lrh[0]) >> 4) & 0xF,
0, qp->ibqp.qp_num,
hdr->lrh[3], hdr->lrh[1]);
goto err;
}
/* Validate the SLID. See Ch. 9.6.1.5 */
if (be16_to_cpu(hdr->lrh[3]) !=
rdma_ah_get_dlid(&qp->remote_ah_attr) ||
ppd_from_ibp(ibp)->port != qp->port_num)
goto err;
if (qp->s_mig_state == IB_MIG_REARM &&
!(bth0 & IB_BTH_MIG_REQ))
qp->s_mig_state = IB_MIG_ARMED;
}
return 0;
err:
return 1;
}
/**
* qib_ruc_loopback - handle UC and RC lookback requests
* @sqp: the sending QP
*
* This is called from qib_do_send() to
* forward a WQE addressed to the same HCA.
* Note that although we are single threaded due to the tasklet, we still
* have to protect against post_send(). We don't have to worry about
* receive interrupts since this is a connected protocol and all packets
* will pass through here.
*/
static void qib_ruc_loopback(struct rvt_qp *sqp)
{
struct qib_ibport *ibp = to_iport(sqp->ibqp.device, sqp->port_num);
struct qib_pportdata *ppd = ppd_from_ibp(ibp);
struct qib_devdata *dd = ppd->dd;
struct rvt_dev_info *rdi = &dd->verbs_dev.rdi;
struct rvt_qp *qp;
struct rvt_swqe *wqe;
struct rvt_sge *sge;
unsigned long flags;
struct ib_wc wc;
u64 sdata;
atomic64_t *maddr;
enum ib_wc_status send_status;
int release;
int ret;
rcu_read_lock();
/*
* Note that we check the responder QP state after
* checking the requester's state.
*/
qp = rvt_lookup_qpn(rdi, &ibp->rvp, sqp->remote_qpn);
if (!qp)
goto done;
spin_lock_irqsave(&sqp->s_lock, flags);
/* Return if we are already busy processing a work request. */
if ((sqp->s_flags & (RVT_S_BUSY | RVT_S_ANY_WAIT)) ||
!(ib_rvt_state_ops[sqp->state] & RVT_PROCESS_OR_FLUSH_SEND))
goto unlock;
sqp->s_flags |= RVT_S_BUSY;
again:
if (sqp->s_last == READ_ONCE(sqp->s_head))
goto clr_busy;
wqe = rvt_get_swqe_ptr(sqp, sqp->s_last);
/* Return if it is not OK to start a new work reqeust. */
if (!(ib_rvt_state_ops[sqp->state] & RVT_PROCESS_NEXT_SEND_OK)) {
if (!(ib_rvt_state_ops[sqp->state] & RVT_FLUSH_SEND))
goto clr_busy;
/* We are in the error state, flush the work request. */
send_status = IB_WC_WR_FLUSH_ERR;
goto flush_send;
}
/*
* We can rely on the entry not changing without the s_lock
* being held until we update s_last.
* We increment s_cur to indicate s_last is in progress.
*/
if (sqp->s_last == sqp->s_cur) {
if (++sqp->s_cur >= sqp->s_size)
sqp->s_cur = 0;
}
spin_unlock_irqrestore(&sqp->s_lock, flags);
if (!qp || !(ib_rvt_state_ops[qp->state] & RVT_PROCESS_RECV_OK) ||
qp->ibqp.qp_type != sqp->ibqp.qp_type) {
ibp->rvp.n_pkt_drops++;
/*
* For RC, the requester would timeout and retry so
* shortcut the timeouts and just signal too many retries.
*/
if (sqp->ibqp.qp_type == IB_QPT_RC)
send_status = IB_WC_RETRY_EXC_ERR;
else
send_status = IB_WC_SUCCESS;
goto serr;
}
memset(&wc, 0, sizeof(wc));
send_status = IB_WC_SUCCESS;
release = 1;
sqp->s_sge.sge = wqe->sg_list[0];
sqp->s_sge.sg_list = wqe->sg_list + 1;
sqp->s_sge.num_sge = wqe->wr.num_sge;
sqp->s_len = wqe->length;
switch (wqe->wr.opcode) {
case IB_WR_SEND_WITH_IMM:
wc.wc_flags = IB_WC_WITH_IMM;
wc.ex.imm_data = wqe->wr.ex.imm_data;
/* FALLTHROUGH */
case IB_WR_SEND:
ret = rvt_get_rwqe(qp, false);
if (ret < 0)
goto op_err;
if (!ret)
goto rnr_nak;
break;
case IB_WR_RDMA_WRITE_WITH_IMM:
if (unlikely(!(qp->qp_access_flags & IB_ACCESS_REMOTE_WRITE)))
goto inv_err;
wc.wc_flags = IB_WC_WITH_IMM;
wc.ex.imm_data = wqe->wr.ex.imm_data;
ret = rvt_get_rwqe(qp, true);
if (ret < 0)
goto op_err;
if (!ret)
goto rnr_nak;
/* FALLTHROUGH */
case IB_WR_RDMA_WRITE:
if (unlikely(!(qp->qp_access_flags & IB_ACCESS_REMOTE_WRITE)))
goto inv_err;
if (wqe->length == 0)
break;
if (unlikely(!rvt_rkey_ok(qp, &qp->r_sge.sge, wqe->length,
wqe->rdma_wr.remote_addr,
wqe->rdma_wr.rkey,
IB_ACCESS_REMOTE_WRITE)))
goto acc_err;
qp->r_sge.sg_list = NULL;
qp->r_sge.num_sge = 1;
qp->r_sge.total_len = wqe->length;
break;
case IB_WR_RDMA_READ:
if (unlikely(!(qp->qp_access_flags & IB_ACCESS_REMOTE_READ)))
goto inv_err;
if (unlikely(!rvt_rkey_ok(qp, &sqp->s_sge.sge, wqe->length,
wqe->rdma_wr.remote_addr,
wqe->rdma_wr.rkey,
IB_ACCESS_REMOTE_READ)))
goto acc_err;
release = 0;
sqp->s_sge.sg_list = NULL;
sqp->s_sge.num_sge = 1;
qp->r_sge.sge = wqe->sg_list[0];
qp->r_sge.sg_list = wqe->sg_list + 1;
qp->r_sge.num_sge = wqe->wr.num_sge;
qp->r_sge.total_len = wqe->length;
break;
case IB_WR_ATOMIC_CMP_AND_SWP:
case IB_WR_ATOMIC_FETCH_AND_ADD:
if (unlikely(!(qp->qp_access_flags & IB_ACCESS_REMOTE_ATOMIC)))
goto inv_err;
if (unlikely(!rvt_rkey_ok(qp, &qp->r_sge.sge, sizeof(u64),
wqe->atomic_wr.remote_addr,
wqe->atomic_wr.rkey,
IB_ACCESS_REMOTE_ATOMIC)))
goto acc_err;
/* Perform atomic OP and save result. */
maddr = (atomic64_t *) qp->r_sge.sge.vaddr;
sdata = wqe->atomic_wr.compare_add;
*(u64 *) sqp->s_sge.sge.vaddr =
(wqe->atomic_wr.wr.opcode == IB_WR_ATOMIC_FETCH_AND_ADD) ?
(u64) atomic64_add_return(sdata, maddr) - sdata :
(u64) cmpxchg((u64 *) qp->r_sge.sge.vaddr,
sdata, wqe->atomic_wr.swap);
rvt_put_mr(qp->r_sge.sge.mr);
qp->r_sge.num_sge = 0;
goto send_comp;
default:
send_status = IB_WC_LOC_QP_OP_ERR;
goto serr;
}
sge = &sqp->s_sge.sge;
while (sqp->s_len) {
u32 len = sqp->s_len;
if (len > sge->length)
len = sge->length;
if (len > sge->sge_length)
len = sge->sge_length;
BUG_ON(len == 0);
qib_copy_sge(&qp->r_sge, sge->vaddr, len, release);
sge->vaddr += len;
sge->length -= len;
sge->sge_length -= len;
if (sge->sge_length == 0) {
if (!release)
rvt_put_mr(sge->mr);
if (--sqp->s_sge.num_sge)
*sge = *sqp->s_sge.sg_list++;
} else if (sge->length == 0 && sge->mr->lkey) {
if (++sge->n >= RVT_SEGSZ) {
if (++sge->m >= sge->mr->mapsz)
break;
sge->n = 0;
}
sge->vaddr =
sge->mr->map[sge->m]->segs[sge->n].vaddr;
sge->length =
sge->mr->map[sge->m]->segs[sge->n].length;
}
sqp->s_len -= len;
}
if (release)
rvt_put_ss(&qp->r_sge);
if (!test_and_clear_bit(RVT_R_WRID_VALID, &qp->r_aflags))
goto send_comp;
if (wqe->wr.opcode == IB_WR_RDMA_WRITE_WITH_IMM)
wc.opcode = IB_WC_RECV_RDMA_WITH_IMM;
else
wc.opcode = IB_WC_RECV;
wc.wr_id = qp->r_wr_id;
wc.status = IB_WC_SUCCESS;
wc.byte_len = wqe->length;
wc.qp = &qp->ibqp;
wc.src_qp = qp->remote_qpn;
wc.slid = rdma_ah_get_dlid(&qp->remote_ah_attr);
wc.sl = rdma_ah_get_sl(&qp->remote_ah_attr);
wc.port_num = 1;
/* Signal completion event if the solicited bit is set. */
rvt_cq_enter(ibcq_to_rvtcq(qp->ibqp.recv_cq), &wc,
wqe->wr.send_flags & IB_SEND_SOLICITED);
send_comp:
spin_lock_irqsave(&sqp->s_lock, flags);
ibp->rvp.n_loop_pkts++;
flush_send:
sqp->s_rnr_retry = sqp->s_rnr_retry_cnt;
qib_send_complete(sqp, wqe, send_status);
goto again;
rnr_nak:
/* Handle RNR NAK */
if (qp->ibqp.qp_type == IB_QPT_UC)
goto send_comp;
ibp->rvp.n_rnr_naks++;
/*
* Note: we don't need the s_lock held since the BUSY flag
* makes this single threaded.
*/
if (sqp->s_rnr_retry == 0) {
send_status = IB_WC_RNR_RETRY_EXC_ERR;
goto serr;
}
if (sqp->s_rnr_retry_cnt < 7)
sqp->s_rnr_retry--;
spin_lock_irqsave(&sqp->s_lock, flags);
if (!(ib_rvt_state_ops[sqp->state] & RVT_PROCESS_RECV_OK))
goto clr_busy;
rvt_add_rnr_timer(sqp, qp->r_min_rnr_timer <<
IB_AETH_CREDIT_SHIFT);
goto clr_busy;
op_err:
send_status = IB_WC_REM_OP_ERR;
wc.status = IB_WC_LOC_QP_OP_ERR;
goto err;
inv_err:
send_status = IB_WC_REM_INV_REQ_ERR;
wc.status = IB_WC_LOC_QP_OP_ERR;
goto err;
acc_err:
send_status = IB_WC_REM_ACCESS_ERR;
wc.status = IB_WC_LOC_PROT_ERR;
err:
/* responder goes to error state */
rvt_rc_error(qp, wc.status);
serr:
spin_lock_irqsave(&sqp->s_lock, flags);
qib_send_complete(sqp, wqe, send_status);
if (sqp->ibqp.qp_type == IB_QPT_RC) {
int lastwqe = rvt_error_qp(sqp, IB_WC_WR_FLUSH_ERR);
sqp->s_flags &= ~RVT_S_BUSY;
spin_unlock_irqrestore(&sqp->s_lock, flags);
if (lastwqe) {
struct ib_event ev;
ev.device = sqp->ibqp.device;
ev.element.qp = &sqp->ibqp;
ev.event = IB_EVENT_QP_LAST_WQE_REACHED;
sqp->ibqp.event_handler(&ev, sqp->ibqp.qp_context);
}
goto done;
}
clr_busy:
sqp->s_flags &= ~RVT_S_BUSY;
unlock:
spin_unlock_irqrestore(&sqp->s_lock, flags);
done:
rcu_read_unlock();
}
/**
* qib_make_grh - construct a GRH header
* @ibp: a pointer to the IB port
* @hdr: a pointer to the GRH header being constructed
* @grh: the global route address to send to
* @hwords: the number of 32 bit words of header being sent
* @nwords: the number of 32 bit words of data being sent
*
* Return the size of the header in 32 bit words.
*/
u32 qib_make_grh(struct qib_ibport *ibp, struct ib_grh *hdr,
const struct ib_global_route *grh, u32 hwords, u32 nwords)
{
hdr->version_tclass_flow =
cpu_to_be32((IB_GRH_VERSION << IB_GRH_VERSION_SHIFT) |
(grh->traffic_class << IB_GRH_TCLASS_SHIFT) |
(grh->flow_label << IB_GRH_FLOW_SHIFT));
hdr->paylen = cpu_to_be16((hwords - 2 + nwords + SIZE_OF_CRC) << 2);
/* next_hdr is defined by C8-7 in ch. 8.4.1 */
hdr->next_hdr = IB_GRH_NEXT_HDR;
hdr->hop_limit = grh->hop_limit;
/* The SGID is 32-bit aligned. */
hdr->sgid.global.subnet_prefix = ibp->rvp.gid_prefix;
if (!grh->sgid_index)
hdr->sgid.global.interface_id = ppd_from_ibp(ibp)->guid;
else if (grh->sgid_index < QIB_GUIDS_PER_PORT)
hdr->sgid.global.interface_id = ibp->guids[grh->sgid_index - 1];
hdr->dgid = grh->dgid;
/* GRH header size in 32-bit words. */
return sizeof(struct ib_grh) / sizeof(u32);
}
void qib_make_ruc_header(struct rvt_qp *qp, struct ib_other_headers *ohdr,
u32 bth0, u32 bth2)
{
struct qib_qp_priv *priv = qp->priv;
struct qib_ibport *ibp = to_iport(qp->ibqp.device, qp->port_num);
u16 lrh0;
u32 nwords;
u32 extra_bytes;
/* Construct the header. */
extra_bytes = -qp->s_cur_size & 3;
nwords = (qp->s_cur_size + extra_bytes) >> 2;
lrh0 = QIB_LRH_BTH;
if (unlikely(rdma_ah_get_ah_flags(&qp->remote_ah_attr) & IB_AH_GRH)) {
qp->s_hdrwords +=
qib_make_grh(ibp, &priv->s_hdr->u.l.grh,
rdma_ah_read_grh(&qp->remote_ah_attr),
qp->s_hdrwords, nwords);
lrh0 = QIB_LRH_GRH;
}
lrh0 |= ibp->sl_to_vl[rdma_ah_get_sl(&qp->remote_ah_attr)] << 12 |
rdma_ah_get_sl(&qp->remote_ah_attr) << 4;
priv->s_hdr->lrh[0] = cpu_to_be16(lrh0);
priv->s_hdr->lrh[1] =
cpu_to_be16(rdma_ah_get_dlid(&qp->remote_ah_attr));
priv->s_hdr->lrh[2] =
cpu_to_be16(qp->s_hdrwords + nwords + SIZE_OF_CRC);
priv->s_hdr->lrh[3] =
cpu_to_be16(ppd_from_ibp(ibp)->lid |
rdma_ah_get_path_bits(&qp->remote_ah_attr));
bth0 |= qib_get_pkey(ibp, qp->s_pkey_index);
bth0 |= extra_bytes << 20;
if (qp->s_mig_state == IB_MIG_MIGRATED)
bth0 |= IB_BTH_MIG_REQ;
ohdr->bth[0] = cpu_to_be32(bth0);
ohdr->bth[1] = cpu_to_be32(qp->remote_qpn);
ohdr->bth[2] = cpu_to_be32(bth2);
this_cpu_inc(ibp->pmastats->n_unicast_xmit);
}
void _qib_do_send(struct work_struct *work)
{
struct qib_qp_priv *priv = container_of(work, struct qib_qp_priv,
s_work);
struct rvt_qp *qp = priv->owner;
qib_do_send(qp);
}
/**
* qib_do_send - perform a send on a QP
* @qp: 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, two threads could send packets out of order.
*/
void qib_do_send(struct rvt_qp *qp)
{
struct qib_qp_priv *priv = qp->priv;
struct qib_ibport *ibp = to_iport(qp->ibqp.device, qp->port_num);
struct qib_pportdata *ppd = ppd_from_ibp(ibp);
int (*make_req)(struct rvt_qp *qp, unsigned long *flags);
unsigned long flags;
if ((qp->ibqp.qp_type == IB_QPT_RC ||
qp->ibqp.qp_type == IB_QPT_UC) &&
(rdma_ah_get_dlid(&qp->remote_ah_attr) &
~((1 << ppd->lmc) - 1)) == ppd->lid) {
qib_ruc_loopback(qp);
return;
}
if (qp->ibqp.qp_type == IB_QPT_RC)
make_req = qib_make_rc_req;
else if (qp->ibqp.qp_type == IB_QPT_UC)
make_req = qib_make_uc_req;
else
make_req = qib_make_ud_req;
spin_lock_irqsave(&qp->s_lock, flags);
/* Return if we are already busy processing a work request. */
if (!qib_send_ok(qp)) {
spin_unlock_irqrestore(&qp->s_lock, flags);
return;
}
qp->s_flags |= RVT_S_BUSY;
do {
/* Check for a constructed packet to be sent. */
if (qp->s_hdrwords != 0) {
spin_unlock_irqrestore(&qp->s_lock, flags);
/*
* If the packet cannot be sent now, return and
* the send tasklet will be woken up later.
*/
if (qib_verbs_send(qp, priv->s_hdr, qp->s_hdrwords,
qp->s_cur_sge, qp->s_cur_size))
return;
/* Record that s_hdr is empty. */
qp->s_hdrwords = 0;
spin_lock_irqsave(&qp->s_lock, flags);
}
} while (make_req(qp, &flags));
spin_unlock_irqrestore(&qp->s_lock, flags);
}
/*
* This should be called with s_lock held.
*/
void qib_send_complete(struct rvt_qp *qp, struct rvt_swqe *wqe,
enum ib_wc_status status)
{
u32 old_last, last;
if (!(ib_rvt_state_ops[qp->state] & RVT_PROCESS_OR_FLUSH_SEND))
return;
last = qp->s_last;
old_last = last;
if (++last >= qp->s_size)
last = 0;
qp->s_last = last;
/* See post_send() */
barrier();
rvt_put_swqe(wqe);
if (qp->ibqp.qp_type == IB_QPT_UD ||
qp->ibqp.qp_type == IB_QPT_SMI ||
qp->ibqp.qp_type == IB_QPT_GSI)
atomic_dec(&ibah_to_rvtah(wqe->ud_wr.ah)->refcount);
rvt_qp_swqe_complete(qp,
wqe,
ib_qib_wc_opcode[wqe->wr.opcode],
status);
if (qp->s_acked == old_last)
qp->s_acked = last;
if (qp->s_cur == old_last)
qp->s_cur = last;
if (qp->s_tail == old_last)
qp->s_tail = last;
if (qp->state == IB_QPS_SQD && last == qp->s_cur)
qp->s_draining = 0;
}