scsi: lpfc: Fix frequency of Release WQE CQEs
authorJames Smart <jsmart2021@gmail.com>
Tue, 30 Jan 2018 23:58:45 +0000 (15:58 -0800)
committerMartin K. Petersen <martin.petersen@oracle.com>
Mon, 12 Feb 2018 16:43:22 +0000 (11:43 -0500)
commit04673e38f56b30cd39b1fa0f386137d818b17781
treec54093f177e6a73f17533b004b88ad854d56c595
parent7928b2cbe55b2a410a0f5c1f154610059c57b1b2
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>
drivers/scsi/lpfc/lpfc_sli.c