RDS/IB: print string constants in more places

This prints the constant identifier for work completion status and rdma
cm event types, like we already do for IB event types.

A core string array helper is added that each string type uses.

Signed-off-by: Zach Brown <zach.brown@oracle.com>
diff --git a/net/rds/ib_send.c b/net/rds/ib_send.c
index 15f7569..808544a 100644
--- a/net/rds/ib_send.c
+++ b/net/rds/ib_send.c
@@ -38,6 +38,40 @@
 #include "rds.h"
 #include "ib.h"
 
+static char *rds_ib_wc_status_strings[] = {
+#define RDS_IB_WC_STATUS_STR(foo) \
+		[IB_WC_##foo] = __stringify(IB_WC_##foo)
+	RDS_IB_WC_STATUS_STR(SUCCESS),
+	RDS_IB_WC_STATUS_STR(LOC_LEN_ERR),
+	RDS_IB_WC_STATUS_STR(LOC_QP_OP_ERR),
+	RDS_IB_WC_STATUS_STR(LOC_EEC_OP_ERR),
+	RDS_IB_WC_STATUS_STR(LOC_PROT_ERR),
+	RDS_IB_WC_STATUS_STR(WR_FLUSH_ERR),
+	RDS_IB_WC_STATUS_STR(MW_BIND_ERR),
+	RDS_IB_WC_STATUS_STR(BAD_RESP_ERR),
+	RDS_IB_WC_STATUS_STR(LOC_ACCESS_ERR),
+	RDS_IB_WC_STATUS_STR(REM_INV_REQ_ERR),
+	RDS_IB_WC_STATUS_STR(REM_ACCESS_ERR),
+	RDS_IB_WC_STATUS_STR(REM_OP_ERR),
+	RDS_IB_WC_STATUS_STR(RETRY_EXC_ERR),
+	RDS_IB_WC_STATUS_STR(RNR_RETRY_EXC_ERR),
+	RDS_IB_WC_STATUS_STR(LOC_RDD_VIOL_ERR),
+	RDS_IB_WC_STATUS_STR(REM_INV_RD_REQ_ERR),
+	RDS_IB_WC_STATUS_STR(REM_ABORT_ERR),
+	RDS_IB_WC_STATUS_STR(INV_EECN_ERR),
+	RDS_IB_WC_STATUS_STR(INV_EEC_STATE_ERR),
+	RDS_IB_WC_STATUS_STR(FATAL_ERR),
+	RDS_IB_WC_STATUS_STR(RESP_TIMEOUT_ERR),
+	RDS_IB_WC_STATUS_STR(GENERAL_ERR),
+#undef RDS_IB_WC_STATUS_STR
+};
+
+char *rds_ib_wc_status_str(enum ib_wc_status status)
+{
+	return rds_str_array(rds_ib_wc_status_strings,
+			     ARRAY_SIZE(rds_ib_wc_status_strings), status);
+}
+
 /*
  * Convert IB-specific error message to RDS error message and call core
  * completion handler.
@@ -257,8 +291,9 @@
 		rdsdebug("ib_req_notify_cq send failed: %d\n", ret);
 
 	while (ib_poll_cq(cq, 1, &wc) > 0) {
-		rdsdebug("wc wr_id 0x%llx status %u byte_len %u imm_data %u\n",
-			 (unsigned long long)wc.wr_id, wc.status, wc.byte_len,
+		rdsdebug("wc wr_id 0x%llx status %u (%s) byte_len %u imm_data %u\n",
+			 (unsigned long long)wc.wr_id, wc.status,
+			 rds_ib_wc_status_str(wc.status), wc.byte_len,
 			 be32_to_cpu(wc.ex.imm_data));
 		rds_ib_stats_inc(s_ib_tx_cq_event);
 
@@ -306,10 +341,10 @@
 
 		/* We expect errors as the qp is drained during shutdown */
 		if (wc.status != IB_WC_SUCCESS && rds_conn_up(conn)) {
-			rds_ib_conn_error(conn,
-				"send completion on %pI4 "
-				"had status %u, disconnecting and reconnecting\n",
-				&conn->c_faddr, wc.status);
+			rds_ib_conn_error(conn, "send completion on %pI4 had status "
+					  "%u (%s), disconnecting and reconnecting\n",
+					  &conn->c_faddr, wc.status,
+					  rds_ib_wc_status_str(wc.status));
 		}
 	}
 }