IB/hfi1: Field not zero-ed when allocating TID flow memory

The field flow->resync_npkts is added for TID RDMA WRITE request and
zero-ed when a TID RDMA WRITE RESP packet is received by the requester.
This field is used to rewind a request during retry in the function
hfi1_tid_rdma_restart_req() shared by both TID RDMA WRITE and TID RDMA
READ requests. Therefore, when a TID RDMA READ request is retried, this
field may not be initialized at all, which causes the retry to start at an
incorrect psn, leading to the drop of the retry request by the responder.

This patch fixes the problem by zeroing out the field when the flow memory
is allocated.

Fixes: 838b6fd2 ("IB/hfi1: TID RDMA RcvArray programming and TID allocation")
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20190715164534.74174.6177.stgit@awfm-01.aw.intel.comReviewed-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: Kaike Wan <kaike.wan@intel.com>
Signed-off-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

drivers/infiniband/hw/hfi1/tid_rdma.c

@@ -1620,6 +1620,7 @@ static int hfi1_kern_exp_rcv_alloc_flows(struct tid_rdma_request *req,
 		flows[i].req = req;
 		flows[i].npagesets = 0;
 		flows[i].pagesets[0].mapped =  0;
+		flows[i].resync_npkts = 0;
 	}
 	req->flows = flows;
 	return 0;