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Commit 154257f3 authored by Ralph Campbell's avatar Ralph Campbell Committed by Roland Dreier
Browse files

IB/ipath: Fix a race condition when generating ACKs 



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

Signed-off-by: default avatarRalph Campbell <ralph.cambpell@qlogic.com>
Signed-off-by: default avatarRobert Walsh <robert.walsh@qlogic.com>
Signed-off-by: default avatarRoland Dreier <rolandd@cisco.com>
parent 6ed89b95

drivers/infiniband/hw/ipath/ipath_rc.c

+15 −13
Original line number Diff line number Diff line
@@ -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. */