[PATCH V2] scsi: mpt3sas: remove redundant wmb

Martin K. Petersen martin.petersen at oracle.com
Wed Apr 19 19:28:30 PDT 2017


Sinan Kaya <okaya at codeaurora.org> writes:

> Due to relaxed ordering requirements on multiple architectures,
> drivers are required to use wmb/rmb/mb combinations when they need to
> guarantee observability between the memory and the HW.
>
> The mpt3sas driver is already using wmb() for this purpose.  However,
> it issues a writel following wmb(). writel() function on arm/arm64
> arhictectures have an embedded wmb() call inside.
>
> This results in unnecessary performance loss and code duplication.
>
> writel already guarantees ordering for both cpu and bus. we don't need
> additional wmb()

Broadcom folks, please review!

-- 
Martin K. Petersen	Oracle Linux Engineering



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