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Date:   Mon, 19 Oct 2020 09:12:11 -0300
From:   Jason Gunthorpe <jgg@nvidia.com>
To:     Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
CC:     "Ursulin, Tvrtko" <tvrtko.ursulin@intel.com>,
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        Leon Romanovsky <leonro@nvidia.com>,
        <linux-rdma@vger.kernel.org>
Subject: Re: dynamic-sg patch has broken rdma_rxe
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On Mon, Oct 19, 2020 at 10:50:14AM +0100, Tvrtko Ursulin wrote:
> > overshoot the max_segment if it is not a multiple of PAGE_SIZE. Simply fix
> > the alignment before starting and don't expose this implementation detail
> > to the callers.
> 
> What does not make complete sense to me is the statement that input
> alignment requirement makes it impossible to connect to DMA layer, but then
> the patch goes to align behind the covers anyway.
> 
> At minimum the kerneldoc should explain that max_segment will still be
> rounded down. But wouldn't it be better for the API to be more explicit and
> just require aligned anyway?

Why?

The API is to not produce sge's with a length longer than max_segment,
it isn't to produce sge's of exactly max_segment.

Everything else is an internal detail

Jason