net/rds: Fix NULL/ERR_PTR inconsistency

Make function "rds_ib_try_reuse_ibmr" return NULL in case
memory region could not be allocated, since callers
simply check if the return value is not NULL.
Signed-off-by: Gerd Rausch <gerd.rausch@oracle.com>
Acked-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/rds/ib_rdma.c

@@ -450,7 +450,7 @@ struct rds_ib_mr *rds_ib_try_reuse_ibmr(struct rds_ib_mr_pool *pool)
 				rds_ib_stats_inc(s_ib_rdma_mr_8k_pool_depleted);
 			else
 				rds_ib_stats_inc(s_ib_rdma_mr_1m_pool_depleted);
-			return ERR_PTR(-EAGAIN);
+			break;
 		}
 
 		/* We do have some empty MRs. Flush them out. */
@@ -464,7 +464,7 @@ struct rds_ib_mr *rds_ib_try_reuse_ibmr(struct rds_ib_mr_pool *pool)
 			return ibmr;
 	}
 
-	return ibmr;
+	return NULL;
 }
 
 static void rds_ib_mr_pool_flush_worker(struct work_struct *work)