scsi: lpfc: Fix frequency of Release WQE CQEs

The driver controls when the hardware sends completions that communicate
consumption of elements from the WQ. This is done by setting a WQEC bit
on a WQE.

The current driver sets it on every Nth WQE posting. However, the driver
isn't clearing the bit if the WQE is reused. Thus, if the queue depth
isn't evenly divisible by N, with enough time, it can be set on every
element, creating a lot of overhead and risking CQ full conditions.

Correct by clearing the bit when not setting it on an Nth element.

Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: James Smart <james.smart@broadcom.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/scsi/lpfc/lpfc_sli.c b/drivers/scsi/lpfc/lpfc_sli.c
index 5f5528a..149f21f 100644 (file)
--- a/drivers/scsi/lpfc/lpfc_sli.c
+++ b/drivers/scsi/lpfc/lpfc_sli.c
@@ -129,6 +129,8 @@ lpfc_sli4_wq_put(struct lpfc_queue *q, union lpfc_wqe *wqe)
        /* set consumption flag every once in a while */
        if (!((q->host_index + 1) % q->entry_repost))
                bf_set(wqe_wqec, &wqe->generic.wqe_com, 1);
+       else
+               bf_set(wqe_wqec, &wqe->generic.wqe_com, 0);
        if (q->phba->sli3_options & LPFC_SLI4_PHWQ_ENABLED)
                bf_set(wqe_wqid, &wqe->generic.wqe_com, q->queue_id);
        lpfc_sli_pcimem_bcopy(wqe, temp_wqe, q->entry_size);