[PATCH for-next] RDMA/rxe fixed bug in rxe_requester

[Bob Pearson <rpearsonhpe@gmail.com>]

The code which limited the number of unacknowledged PSNs was incorrect.
The PSNs are limited to 24 bits and wrap back to zero from 0x00ffffff.
The test was computing a 32 bit value which wraps at 32 bits so that
qp->req.psn can appear smaller than the limit when it is actually larger.

Replace '>' test with psn_compare which is used for other PSN comparisons
and correctly handles the 24 bit size.

Fixes: 8700e3e7c485 ("Soft RoCE (RXE) - The software RoCE driver")
Signed-off-by: Bob Pearson <rpearson@hpe.com>
---
 drivers/infiniband/sw/rxe/rxe_req.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/infiniband/sw/rxe/rxe_req.c b/drivers/infiniband/sw/rxe/rxe_req.c
index af3923bf0a36..d4917646641a 100644
--- a/drivers/infiniband/sw/rxe/rxe_req.c
+++ b/drivers/infiniband/sw/rxe/rxe_req.c
@@ -634,7 +634,8 @@ int rxe_requester(void *arg)
 	}
 
 	if (unlikely(qp_type(qp) == IB_QPT_RC &&
-		     qp->req.psn > (qp->comp.psn + RXE_MAX_UNACKED_PSNS))) {
+		psn_compare(qp->req.psn, (qp->comp.psn +
+				RXE_MAX_UNACKED_PSNS)) > 0)) {
 		qp->req.wait_psn = 1;
 		goto exit;
 	}
-- 
2.25.1