[PATCH for-next v2 11/12] RDMA/rxe: Get rid of pkt resend on err

[Bob Pearson <rpearsonhpe@gmail.com>]

Currently the rxe_driver detects packet drops by ip_local_out()
which occur before the packet is sent on the wire and attempts to
resend them. This is redundant with the usual retry mechanism which
covers packets that get dropped in transit to or from the remote node.

The way this is implemented is not robust since it sets need_req_skb
and waits for the number of local skbs outstanding for this qp to
drop below a low water mark. This is racy since the skb may
be sent to the destructor before the requester can set the
need_req_skb flag. This will cause a deadlock in the send path for
that qp.

This patch removes this mechanism since the normal retry path will
correct the error and resend the packet and it makes no difference
if the packet is dropped locally or later.

Signed-off-by: Bob Pearson <rpearsonhpe@gmail.com>
---
 drivers/infiniband/sw/rxe/rxe_net.c |  7 +------
 drivers/infiniband/sw/rxe/rxe_req.c | 14 ++------------
 2 files changed, 3 insertions(+), 18 deletions(-)

diff --git a/drivers/infiniband/sw/rxe/rxe_net.c b/drivers/infiniband/sw/rxe/rxe_net.c
index d081409450a4..b58eab75df97 100644
--- a/drivers/infiniband/sw/rxe/rxe_net.c
+++ b/drivers/infiniband/sw/rxe/rxe_net.c
@@ -371,12 +371,7 @@ static int rxe_send(struct sk_buff *skb, struct rxe_pkt_info *pkt)
 	else
 		err = ip6_local_out(dev_net(skb_dst(skb)->dev), skb->sk, skb);
 
-	if (unlikely(net_xmit_eval(err))) {
-		rxe_dbg_qp(pkt->qp, "error sending packet: %d\n", err);
-		return -EAGAIN;
-	}
-
-	return 0;
+	return err;
 }
 
 /* fix up a send packet to match the packets
diff --git a/drivers/infiniband/sw/rxe/rxe_req.c b/drivers/infiniband/sw/rxe/rxe_req.c
index 34c55dee0774..cd14c4c2dff9 100644
--- a/drivers/infiniband/sw/rxe/rxe_req.c
+++ b/drivers/infiniband/sw/rxe/rxe_req.c
@@ -802,18 +802,8 @@ int rxe_requester(struct rxe_qp *qp)
 
 	err = rxe_xmit_packet(qp, &pkt, skb);
 	if (err) {
-		if (err != -EAGAIN) {
-			wqe->status = IB_WC_LOC_QP_OP_ERR;
-			goto err;
-		}
-
-		/* force a delay until the dropped packet is freed and
-		 * the send queue is drained below the low water mark
-		 */
-		qp->need_req_skb = 1;
-
-		rxe_sched_task(&qp->send_task);
-		goto exit;
+		wqe->status = IB_WC_LOC_QP_OP_ERR;
+		goto err;
 	}
 
 	update_wqe_state(qp, wqe, &pkt);
-- 
2.43.0