[PATCH 2/2] RDMA/rxe: Handle remote errors in the midst of a Read reply sequence

[Daisuke Matsuda <matsuda-daisuke@fujitsu.com>]

Requesting nodes do not handle a reported error correctly if it is
generated in the middle of multi-packet Read responses, and the node tries
to resend the request endlessly. Let completer terminate the connection in
that case.

Signed-off-by: Daisuke Matsuda <matsuda-daisuke@fujitsu.com>
---
FOR REVIEWERS:
  I referred to IB Specification Vol 1-Revision-1.5 to make this patch.
  Please see Ch.9.9.2.2, Ch.9.9.2.4.2 and Table 59.

 drivers/infiniband/sw/rxe/rxe_comp.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/infiniband/sw/rxe/rxe_comp.c b/drivers/infiniband/sw/rxe/rxe_comp.c
index fb0c008af78c..c9170dd99f3a 100644
--- a/drivers/infiniband/sw/rxe/rxe_comp.c
+++ b/drivers/infiniband/sw/rxe/rxe_comp.c
@@ -200,6 +200,10 @@ static inline enum comp_state check_psn(struct rxe_qp *qp,
 		 */
 		if (pkt->psn == wqe->last_psn)
 			return COMPST_COMP_ACK;
+		else if (pkt->opcode == IB_OPCODE_RC_ACKNOWLEDGE &&
+			 (qp->comp.opcode == IB_OPCODE_RC_RDMA_READ_RESPONSE_FIRST ||
+			  qp->comp.opcode == IB_OPCODE_RC_RDMA_READ_RESPONSE_MIDDLE))
+			return COMPST_CHECK_ACK;
 		else
 			return COMPST_DONE;
 	} else if ((diff > 0) && (wqe->mask & WR_ATOMIC_OR_READ_MASK)) {
@@ -228,6 +232,10 @@ static inline enum comp_state check_ack(struct rxe_qp *qp,
 
 	case IB_OPCODE_RC_RDMA_READ_RESPONSE_FIRST:
 	case IB_OPCODE_RC_RDMA_READ_RESPONSE_MIDDLE:
+		/* Check NAK code to handle a remote error */
+		if (pkt->opcode == IB_OPCODE_RC_ACKNOWLEDGE)
+			break;
+
 		if (pkt->opcode != IB_OPCODE_RC_RDMA_READ_RESPONSE_MIDDLE &&
 		    pkt->opcode != IB_OPCODE_RC_RDMA_READ_RESPONSE_LAST) {
 			/* read retries of partial data may restart from
-- 
2.31.1