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IB/ipath: Fix a race condition when generating ACKs

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Fix a problem where simple ACKs can be sent ahead of RDMA read
responses thus implicitly NAKing the RDMA read.

Signed-off-by: Ralph Campbell <ralph.cambpell@qlogic.com>
Signed-off-by: Robert Walsh <robert.walsh@qlogic.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
This commit is contained in:
Ralph Campbell 2007-05-03 12:43:03 -07:00 committed by Roland Dreier
parent 6ed89b9574
commit 154257f362
1 changed files with 15 additions and 13 deletions
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28
drivers/infiniband/hw/ipath/ipath_rc.c
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@ -98,13 +98,21 @@ static int ipath_make_rc_ack(struct ipath_qp *qp,
case OP(RDMA_READ_RESPONSE_LAST):
case OP(RDMA_READ_RESPONSE_ONLY):
case OP(ATOMIC_ACKNOWLEDGE):
qp->s_ack_state = OP(ACKNOWLEDGE);
/*
* We can increment the tail pointer now that the last
* response has been sent instead of only being
* constructed.
*/
if (++qp->s_tail_ack_queue > IPATH_MAX_RDMA_ATOMIC)
qp->s_tail_ack_queue = 0;
/* FALLTHROUGH */
case OP(SEND_ONLY):
case OP(ACKNOWLEDGE):
/* Check for no next entry in the queue. */
if (qp->r_head_ack_queue == qp->s_tail_ack_queue) {
if (qp->s_flags & IPATH_S_ACK_PENDING)
goto normal;
qp->s_ack_state = OP(ACKNOWLEDGE);
goto bail;
}
@ -117,12 +125,8 @@ static int ipath_make_rc_ack(struct ipath_qp *qp,
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);
if (++qp->s_tail_ack_queue >
IPATH_MAX_RDMA_ATOMIC)
qp->s_tail_ack_queue = 0;
}
ohdr->u.aeth = ipath_compute_aeth(qp);
hwords++;
qp->s_ack_rdma_psn = e->psn;
@ -139,8 +143,6 @@ static int ipath_make_rc_ack(struct ipath_qp *qp,
cpu_to_be32(e->atomic_data);
hwords += sizeof(ohdr->u.at) / sizeof(u32);
bth2 = e->psn;
if (++qp->s_tail_ack_queue > IPATH_MAX_RDMA_ATOMIC)
qp->s_tail_ack_queue = 0;
}
bth0 = qp->s_ack_state << 24;
break;
@ -156,8 +158,6 @@ static int ipath_make_rc_ack(struct ipath_qp *qp,
ohdr->u.aeth = ipath_compute_aeth(qp);
hwords++;
qp->s_ack_state = OP(RDMA_READ_RESPONSE_LAST);
if (++qp->s_tail_ack_queue > IPATH_MAX_RDMA_ATOMIC)
qp->s_tail_ack_queue = 0;
}
bth0 = qp->s_ack_state << 24;
bth2 = qp->s_ack_rdma_psn++ & IPATH_PSN_MASK;
@ -171,7 +171,7 @@ static int ipath_make_rc_ack(struct ipath_qp *qp,
* the ACK before setting s_ack_state to ACKNOWLEDGE
* (see above).
*/
qp->s_ack_state = OP(ATOMIC_ACKNOWLEDGE);
qp->s_ack_state = OP(SEND_ONLY);
qp->s_flags &= ~IPATH_S_ACK_PENDING;
qp->s_cur_sge = NULL;
if (qp->s_nak_state)
@ -223,7 +223,7 @@ int ipath_make_rc_req(struct ipath_qp *qp,
/* Sending responses has higher priority over sending requests. */
if ((qp->r_head_ack_queue != qp->s_tail_ack_queue ||
(qp->s_flags & IPATH_S_ACK_PENDING) ||
qp->s_ack_state != IB_OPCODE_RC_ACKNOWLEDGE) &&
qp->s_ack_state != OP(ACKNOWLEDGE)) &&
ipath_make_rc_ack(qp, ohdr, pmtu, bth0p, bth2p))
goto done;
@ -585,7 +585,9 @@ static void send_rc_ack(struct ipath_qp *qp)
unsigned long flags;
/* Don't send ACK or NAK if a RDMA read or atomic is pending. */
if (qp->r_head_ack_queue != qp->s_tail_ack_queue)
if (qp->r_head_ack_queue != qp->s_tail_ack_queue ||
(qp->s_flags & IPATH_S_ACK_PENDING) ||
qp->s_ack_state != OP(ACKNOWLEDGE))
goto queue_ack;
/* Construct the header. */