scsi: lpfc: Fix frequency of Release WQE CQEs
authorJames Smart <jsmart2021@gmail.com>
Tue, 30 Jan 2018 23:58:45 +0000 (15:58 -0800)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Fri, 25 May 2018 14:13:09 +0000 (16:13 +0200)
commite0d35e31c5257438ab6824ab27dd9ac06277a58f
tree4b823d91b8484ca39c9ca5e7b04f58b8cb14a8c8
parent24678510078c388e89a14545790f28c62c010914
scsi: lpfc: Fix frequency of Release WQE CQEs

[ Upstream commit 04673e38f56b30cd39b1fa0f386137d818b17781 ]

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>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
drivers/scsi/lpfc/lpfc_sli.c