netdev - Re: [PATCH V2] net/mlx4: Get rid of page operation after dma_alloc

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Date:   Wed, 19 Dec 2018 08:25:30 +0100
From:   Christoph Hellwig <hch@....de>
To:     Stephen Warren <swarren@...dotorg.org>
Cc:     Christoph Hellwig <hch@....de>, Tariq Toukan <tariqt@...lanox.com>,
        xavier.huwei@...wei.com, netdev@...r.kernel.org,
        linux-rdma@...r.kernel.org, Doug Ledford <dledford@...hat.com>,
        Jason Gunthorpe <jgg@...lanox.com>,
        Stephen Warren <swarren@...dia.com>
Subject: Re: [PATCH V2] net/mlx4: Get rid of page operation after
 dma_alloc_coherent

On Tue, Dec 18, 2018 at 05:12:41PM -0700, Stephen Warren wrote:
> On 12/18/18 1:56 PM, Christoph Hellwig wrote:
>> This goes in the right direction, but I think we need to stop
>> abusing the scatterlist for the coherent mapping entirely.  Something
>> like the patch below (based on yours):
>
> Oh, it was simple to get rid of the sg list usage than I thought; I'd 
> assume it would be touched in a bunch of other files.
>
> I had to make the additions shown below to get the adapter to get the 
> driver to probe without errors, but with these changes, ibping, ib_read_bw, 
> and ib_write_bw all work both directions:

I think the new coherent flag should probably use a bool instead of int,
even despite the fact that the old one still uses bool.

It might also be worth checking if we need the per-chunk and per-table
coherent flags, or if the per-chunk one is enough.

Otherwise this looks fine, feel free to resend it under your name as
you did the original patch and all the analysis and testing.