[PATCH for-next] RDMA/rxe: Fix incorrect fencing

[Bob Pearson <rpearsonhpe@gmail.com>]

Currently the rxe driver checks if any previous operation
is not complete to determine if a fence wait is required.
This is not correct. For a regular fence only previous
read or atomic operations must be complete while for a local
invalidate fence all previous operations must be complete.
This patch corrects this behavior.

Fixes: 8700e3e7c4857 ("Soft RoCE (RXE) - The software RoCE driver")
Signed-off-by: Bob Pearson <rpearsonhpe@gmail.com>
---
 drivers/infiniband/sw/rxe/rxe_req.c | 42 ++++++++++++++++++++++++-----
 1 file changed, 36 insertions(+), 6 deletions(-)

diff --git a/drivers/infiniband/sw/rxe/rxe_req.c b/drivers/infiniband/sw/rxe/rxe_req.c
index ae5fbc79dd5c..f36263855a45 100644
--- a/drivers/infiniband/sw/rxe/rxe_req.c
+++ b/drivers/infiniband/sw/rxe/rxe_req.c
@@ -163,16 +163,41 @@ static struct rxe_send_wqe *req_next_wqe(struct rxe_qp *qp)
 		     (wqe->state != wqe_state_processing)))
 		return NULL;
 
-	if (unlikely((wqe->wr.send_flags & IB_SEND_FENCE) &&
-						     (index != cons))) {
-		qp->req.wait_fence = 1;
-		return NULL;
-	}
-
 	wqe->mask = wr_opcode_mask(wqe->wr.opcode, qp);
 	return wqe;
 }
 
+/**
+ * rxe_wqe_is_fenced - check if next wqe is fenced
+ * @qp: the queue pair
+ * @wqe: the next wqe
+ *
+ * Returns: 1 if wqe is fenced (needs to wait)
+ *	    0 if wqe is good to go
+ */
+static int rxe_wqe_is_fenced(struct rxe_qp *qp, struct rxe_send_wqe *wqe)
+{
+	unsigned int cons;
+
+	if (!(wqe->wr.send_flags & IB_SEND_FENCE))
+		return 0;
+
+	cons = queue_get_consumer(qp->sq.queue, QUEUE_TYPE_FROM_CLIENT);
+
+	/* Local invalidate fence (LIF) see IBA 10.6.5.1
+	 * Requires ALL previous operations on the send queue
+	 * are complete.
+	 */
+	if (wqe->wr.opcode == IB_WR_LOCAL_INV)
+		return qp->req.wqe_index != cons;
+
+	/* Fence see IBA 10.8.3.3
+	 * Requires that all previous read and atomic operations
+	 * are complete.
+	 */
+	return atomic_read(&qp->req.rd_atomic) != qp->attr.max_rd_atomic;
+}
+
 static int next_opcode_rc(struct rxe_qp *qp, u32 opcode, int fits)
 {
 	switch (opcode) {
@@ -636,6 +661,11 @@ int rxe_requester(void *arg)
 	if (unlikely(!wqe))
 		goto exit;
 
+	if (rxe_wqe_is_fenced(qp, wqe)) {
+		qp->req.wait_fence = 1;
+		goto exit;
+	}
+
 	if (wqe->mask & WR_LOCAL_OP_MASK) {
 		ret = rxe_do_local_ops(qp, wqe);
 		if (unlikely(ret))

base-commit: c5eb0a61238dd6faf37f58c9ce61c9980aaffd7a
-- 
2.34.1