From: James Smart <jsmart2021@gmail.com>
Date: Tue, 30 Jan 2018 15:58:45 -0800
Subject: scsi: lpfc: Fix frequency of Release WQE CQEs
Patch-mainline: v4.17-rc1
Git-commit: 04673e38f56b30cd39b1fa0f386137d818b17781
References: bsc#1080657

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>
Acked-by: Johannes Thumshirn <jthumshirn@suse.de>
---
 drivers/scsi/lpfc/lpfc_sli.c |    2 ++
 1 file changed, 2 insertions(+)

--- 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, u
 	/* 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);