IB/ehca: Replace modulus operations in flush error completion path

With the latest flush error completion patch we introduced modulus
operation to calculate the next index within a qmap.  Based on
comments from other mailing lists we decided to optimize this
operation by using an addition and an if-statement instead of modulus,
even though this is on the error path.

Signed-off-by: Stefan Roscher <stefan.roscher@de.ibm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

1 files changed, 6 insertions, 7 deletions

diff --git a/drivers/infiniband/hw/ehca/ehca_reqs.c b/drivers/infiniband/hw/ehca/ehca_reqs.c
index 00a648f4316c..c7112686782f 100644
--- a/drivers/infiniband/hw/ehca/ehca_reqs.c
+++ b/drivers/infiniband/hw/ehca/ehca_reqs.c
@@ -726,13 +726,13 @@ repoll:
                  * set left_to_poll to 0 because in error state, we will not
                  * get any additional CQEs
                  */
-                my_qp->sq_map.next_wqe_idx = (my_qp->sq_map.tail + 1) %
-                                                my_qp->sq_map.entries;
+                my_qp->sq_map.next_wqe_idx = next_index(my_qp->sq_map.tail,
+                                                        my_qp->sq_map.entries);
                 my_qp->sq_map.left_to_poll = 0;
                 ehca_add_to_err_list(my_qp, 1);
 
-                my_qp->rq_map.next_wqe_idx = (my_qp->rq_map.tail + 1) %
-                                                my_qp->rq_map.entries;
+                my_qp->rq_map.next_wqe_idx = next_index(my_qp->rq_map.tail,
+                                                        my_qp->rq_map.entries);
                 my_qp->rq_map.left_to_poll = 0;
                 if (HAS_RQ(my_qp))
                         ehca_add_to_err_list(my_qp, 0);
@@ -860,9 +860,8 @@ static int generate_flush_cqes(struct ehca_qp *my_qp, struct ib_cq *cq,
 
                 /* mark as reported and advance next_wqe pointer */
                 qmap_entry->reported = 1;
-                qmap->next_wqe_idx++;
-                if (qmap->next_wqe_idx == qmap->entries)
-                        qmap->next_wqe_idx = 0;
+                qmap->next_wqe_idx = next_index(qmap->next_wqe_idx,
+                                                qmap->entries);
                 qmap_entry = &qmap->map[qmap->next_wqe_idx];
 
                 wc++; nr++;