IB/Verbs: Use management helper rdma_cap_read_multi_sge()

Introduce helper rdma_cap_read_multi_sge() to help us check if the port of an
IB device support RDMA Read Multiple Scatter-Gather Entries.
Signed-off-by: Michael Wang <yun.wang@profitbricks.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Tested-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Sean Hefty <sean.hefty@intel.com>
Reviewed-by: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
Tested-by: Doug Ledford <dledford@redhat.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

include/rdma/ib_verbs.h

@@ -1864,6 +1864,22 @@ static inline bool rdma_cap_ib_mcast(struct ib_device *device, u8 port_num)
 	return rdma_cap_ib_sa(device, port_num);
 }
 
+/**
+ * rdma_cap_read_multi_sge - Check if the port of device has the capability
+ * RDMA Read Multiple Scatter-Gather Entries.
+ *
+ * @device: Device to be checked
+ * @port_num: Port number of the device
+ *
+ * Return false when port of the device don't support
+ * RDMA Read Multiple Scatter-Gather Entries.
+ */
+static inline bool rdma_cap_read_multi_sge(struct ib_device *device,
+					   u8 port_num)
+{
+	return !rdma_protocol_iwarp(device, port_num);
+}
+
 int ib_query_gid(struct ib_device *device,
 		 u8 port_num, int index, union ib_gid *gid);
 

net/sunrpc/xprtrdma/svc_rdma_recvfrom.c

@@ -117,8 +117,8 @@ static void rdma_build_arg_xdr(struct svc_rqst *rqstp,
 
 static int rdma_read_max_sge(struct svcxprt_rdma *xprt, int sge_count)
 {
-	if (rdma_protocol_iwarp(xprt->sc_cm_id->device,
-				xprt->sc_cm_id->port_num))
+	if (!rdma_cap_read_multi_sge(xprt->sc_cm_id->device,
+				     xprt->sc_cm_id->port_num))
 		return 1;
 	else
 		return min_t(int, sge_count, xprt->sc_max_sge);