xprtrdma: Take struct ib_qp_attr and ib_qp_init_attr off the stack

Reduce stack footprint of the connection upcall handler function.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

net/sunrpc/xprtrdma/verbs.c

@@ -425,8 +425,8 @@ rpcrdma_conn_upcall(struct rdma_cm_id *id, struct rdma_cm_event *event)
 #if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
 	struct sockaddr_in *addr = (struct sockaddr_in *) &ep->rep_remote_addr;
 #endif
-	struct ib_qp_attr attr;
-	struct ib_qp_init_attr iattr;
+	struct ib_qp_attr *attr = &ia->ri_qp_attr;
+	struct ib_qp_init_attr *iattr = &ia->ri_qp_init_attr;
 	int connstate = 0;
 
 	switch (event->event) {
@@ -449,12 +449,13 @@ rpcrdma_conn_upcall(struct rdma_cm_id *id, struct rdma_cm_event *event)
 		break;
 	case RDMA_CM_EVENT_ESTABLISHED:
 		connstate = 1;
-		ib_query_qp(ia->ri_id->qp, &attr,
-			IB_QP_MAX_QP_RD_ATOMIC | IB_QP_MAX_DEST_RD_ATOMIC,
-			&iattr);
+		ib_query_qp(ia->ri_id->qp, attr,
+			    IB_QP_MAX_QP_RD_ATOMIC | IB_QP_MAX_DEST_RD_ATOMIC,
+			    iattr);
 		dprintk("RPC:       %s: %d responder resources"
 			" (%d initiator)\n",
-			__func__, attr.max_dest_rd_atomic, attr.max_rd_atomic);
+			__func__, attr->max_dest_rd_atomic,
+			attr->max_rd_atomic);
 		goto connected;
 	case RDMA_CM_EVENT_CONNECT_ERROR:
 		connstate = -ENOTCONN;
@@ -487,7 +488,7 @@ rpcrdma_conn_upcall(struct rdma_cm_id *id, struct rdma_cm_event *event)
 
 #if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
 	if (connstate == 1) {
-		int ird = attr.max_dest_rd_atomic;
+		int ird = attr->max_dest_rd_atomic;
 		int tird = ep->rep_remote_cma.responder_resources;
 		printk(KERN_INFO "rpcrdma: connection to %pI4:%u "
 			"on %s, memreg %d slots %d ird %d%s\n",

net/sunrpc/xprtrdma/xprt_rdma.h

@@ -71,6 +71,8 @@ struct rpcrdma_ia {
 	enum rpcrdma_memreg	ri_memreg_strategy;
 	unsigned int		ri_max_frmr_depth;
 	struct ib_device_attr	ri_devattr;
+	struct ib_qp_attr	ri_qp_attr;
+	struct ib_qp_init_attr	ri_qp_init_attr;
 };
 
 /*