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IB/qib: Issue pre-emptive NAKs on eager buffer overflow

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Under congestion resulting in eager buffer overflow attempt to send
pre-emptive NAKs if header queue entries with TID errors are generated
and a valid header is present.  This prevents long timeouts and flow
restarts if a trailing set of packets are dropped due to eager
overflows.  Pre-emptive NAKs are currently only supported for RDMA
writes.

Signed-off-by: Mike Marciniszyn <mike.marciniszyn@qlogic.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
This commit is contained in:
Mike Marciniszyn 2011-01-10 17:42:22 -08:00 committed by Roland Dreier
parent 2a600f14d2
commit 994bcd28a3
1 changed files with 137 additions and 4 deletions
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141
drivers/infiniband/hw/qib/qib_driver.c
View file

@ -289,14 +289,147 @@ static inline void *qib_get_egrbuf(const struct qib_ctxtdata *rcd, u32 etail)
* Returns 1 if error was a CRC, else 0.
* Needed for some chip's synthesized error counters.
*/
static u32 qib_rcv_hdrerr(struct qib_pportdata *ppd, u32 ctxt,
u32 eflags, u32 l, u32 etail, __le32 *rhf_addr,
struct qib_message_header *hdr)
static u32 qib_rcv_hdrerr(struct qib_ctxtdata *rcd, struct qib_pportdata *ppd,
u32 ctxt, u32 eflags, u32 l, u32 etail,
__le32 *rhf_addr, struct qib_message_header *rhdr)
{
u32 ret = 0;
if (eflags & (QLOGIC_IB_RHF_H_ICRCERR | QLOGIC_IB_RHF_H_VCRCERR))
ret = 1;
else if (eflags == QLOGIC_IB_RHF_H_TIDERR) {
/* For TIDERR and RC QPs premptively schedule a NAK */
struct qib_ib_header *hdr = (struct qib_ib_header *) rhdr;
struct qib_other_headers *ohdr = NULL;
struct qib_ibport *ibp = &ppd->ibport_data;
struct qib_qp *qp = NULL;
u32 tlen = qib_hdrget_length_in_bytes(rhf_addr);
u16 lid = be16_to_cpu(hdr->lrh[1]);
int lnh = be16_to_cpu(hdr->lrh[0]) & 3;
u32 qp_num;
u32 opcode;
u32 psn;
int diff;
unsigned long flags;
/* Sanity check packet */
if (tlen < 24)
goto drop;
if (lid < QIB_MULTICAST_LID_BASE) {
lid &= ~((1 << ppd->lmc) - 1);
if (unlikely(lid != ppd->lid))
goto drop;
}
/* Check for GRH */
if (lnh == QIB_LRH_BTH)
ohdr = &hdr->u.oth;
else if (lnh == QIB_LRH_GRH) {
u32 vtf;
ohdr = &hdr->u.l.oth;
if (hdr->u.l.grh.next_hdr != IB_GRH_NEXT_HDR)
goto drop;
vtf = be32_to_cpu(hdr->u.l.grh.version_tclass_flow);
if ((vtf >> IB_GRH_VERSION_SHIFT) != IB_GRH_VERSION)
goto drop;
} else
goto drop;
/* Get opcode and PSN from packet */
opcode = be32_to_cpu(ohdr->bth[0]);
opcode >>= 24;
psn = be32_to_cpu(ohdr->bth[2]);
/* Get the destination QP number. */
qp_num = be32_to_cpu(ohdr->bth[1]) & QIB_QPN_MASK;
if (qp_num != QIB_MULTICAST_QPN) {
int ruc_res;
qp = qib_lookup_qpn(ibp, qp_num);
if (!qp)
goto drop;
/*
* Handle only RC QPs - for other QP types drop error
* packet.
*/
spin_lock(&qp->r_lock);
/* Check for valid receive state. */
if (!(ib_qib_state_ops[qp->state] &
QIB_PROCESS_RECV_OK)) {
ibp->n_pkt_drops++;
goto unlock;
}
switch (qp->ibqp.qp_type) {
case IB_QPT_RC:
spin_lock_irqsave(&qp->s_lock, flags);
ruc_res =
qib_ruc_check_hdr(
ibp, hdr,
lnh == QIB_LRH_GRH,
qp,
be32_to_cpu(ohdr->bth[0]));
if (ruc_res) {
spin_unlock_irqrestore(&qp->s_lock,
flags);
goto unlock;
}
spin_unlock_irqrestore(&qp->s_lock, flags);
/* Only deal with RDMA Writes for now */
if (opcode <
IB_OPCODE_RC_RDMA_READ_RESPONSE_FIRST) {
diff = qib_cmp24(psn, qp->r_psn);
if (!qp->r_nak_state && diff >= 0) {
ibp->n_rc_seqnak++;
qp->r_nak_state =
IB_NAK_PSN_ERROR;
/* Use the expected PSN. */
qp->r_ack_psn = qp->r_psn;
/*
* Wait to send the sequence
* NAK until all packets
* in the receive queue have
* been processed.
* Otherwise, we end up
* propagating congestion.
*/
if (list_empty(&qp->rspwait)) {
qp->r_flags |=
QIB_R_RSP_NAK;
atomic_inc(
&qp->refcount);
list_add_tail(
&qp->rspwait,
&rcd->qp_wait_list);
}
} /* Out of sequence NAK */
} /* QP Request NAKs */
break;
case IB_QPT_SMI:
case IB_QPT_GSI:
case IB_QPT_UD:
case IB_QPT_UC:
default:
/* For now don't handle any other QP types */
break;
}
unlock:
spin_unlock(&qp->r_lock);
/*
* Notify qib_destroy_qp() if it is waiting
* for us to finish.
*/
if (atomic_dec_and_test(&qp->refcount))
wake_up(&qp->wait);
} /* Unicast QP */
} /* Valid packet with TIDErr */
drop:
return ret;
}
@ -376,7 +509,7 @@ u32 qib_kreceive(struct qib_ctxtdata *rcd, u32 *llic, u32 *npkts)
* packets; only qibhdrerr should be set.
*/
if (unlikely(eflags))
crcs += qib_rcv_hdrerr(ppd, rcd->ctxt, eflags, l,
crcs += qib_rcv_hdrerr(rcd, ppd, rcd->ctxt, eflags, l,
etail, rhf_addr, hdr);
else if (etype == RCVHQ_RCV_TYPE_NON_KD) {
qib_ib_rcv(rcd, hdr, ebuf, tlen);