Re: [PATCH 3/7] RDMA/qedr: eliminate duplicate barriers on weakly-ordered archs

From: Jason Gunthorpe
Date: Wed Mar 14 2018 - 00:13:02 EST


On Tue, Mar 13, 2018 at 11:20:24PM -0400, Sinan Kaya wrote:
> Code includes wmb() followed by writel() in multiple places. writel()
> already has a barrier on some architectures like arm64.
>
> This ends up CPU observing two barriers back to back before executing the
> register write.
>
> Since code already has an explicit barrier call, changing writel() to
> writel_relaxed().
>
> Signed-off-by: Sinan Kaya <okaya@xxxxxxxxxxxxxx>
> drivers/infiniband/hw/qedr/verbs.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)

Sure matches my understanding of writel_relaxed

This is part of a series, should we take just this patch through the
rdma tree? If not:

Acked-by: Jason Gunthorpe <jgg@xxxxxxxxxxxx>

Thanks,
Jason