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From: Jason Gunthorpe <jgg@nvidia.com>
To: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Cc: "Ursulin, Tvrtko" <tvrtko.ursulin@intel.com>,
	Maor Gottlieb <maorg@nvidia.com>, Christoph Hellwig <hch@lst.de>,
	Gal Pressman <galpress@amazon.com>,
	Bob Pearson <rpearsonhpe@gmail.com>,
	Leon Romanovsky <leonro@nvidia.com>, <linux-rdma@vger.kernel.org>
Subject: Re: dynamic-sg patch has broken rdma_rxe
Date: Mon, 19 Oct 2020 09:12:11 -0300
Message-ID: <20201019121211.GC6219@nvidia.com> (raw)
In-Reply-To: <9fa38ed1-605e-f0f6-6cb6-70b800a1831a@linux.intel.com>

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

  reply index

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-13 14:33 Bob Pearson
2020-10-13 16:34 ` Bob Pearson
2020-10-14 22:51 ` Jason Gunthorpe
2020-10-15  7:44   ` Maor Gottlieb
2020-10-15 11:23     ` Gal Pressman
2020-10-15 12:21       ` Maor Gottlieb
2020-10-16  0:31         ` Jason Gunthorpe
2020-10-16  7:13           ` Christoph Hellwig
     [not found]           ` <796ca31aed8f469c957cb850385b9d09@intel.com>
2020-10-16 11:58             ` Jason Gunthorpe
2020-10-19  9:50               ` Tvrtko Ursulin
2020-10-19 12:12                 ` Jason Gunthorpe [this message]
2020-10-19 12:29                   ` Tvrtko Ursulin
2020-10-19 12:48                     ` Jason Gunthorpe
2020-10-20 11:37                       ` Tvrtko Ursulin
2020-10-20 11:47                         ` Jason Gunthorpe
2020-10-20 12:31                           ` Tvrtko Ursulin
2020-10-20 12:56                             ` Jason Gunthorpe
2020-10-20 13:09                               ` Tvrtko Ursulin
2020-10-20 13:32                                 ` Jason Gunthorpe
2020-10-15 15:35     ` Bob Pearson

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