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Message-ID: <20210316075821.GB15949@lst.de>
Date: Tue, 16 Mar 2021 08:58:21 +0100
From: Christoph Hellwig <hch@....de>
To: Logan Gunthorpe <logang@...tatee.com>
Cc: Robin Murphy <robin.murphy@....com>, linux-kernel@...r.kernel.org,
linux-nvme@...ts.infradead.org, linux-block@...r.kernel.org,
linux-pci@...r.kernel.org, linux-mm@...ck.org,
iommu@...ts.linux-foundation.org,
Minturn Dave B <dave.b.minturn@...el.com>,
John Hubbard <jhubbard@...dia.com>,
Dave Hansen <dave.hansen@...ux.intel.com>,
Matthew Wilcox <willy@...radead.org>,
Christian König <christian.koenig@....com>,
Jason Gunthorpe <jgg@...pe.ca>,
Jason Ekstrand <jason@...kstrand.net>,
Daniel Vetter <daniel.vetter@...ll.ch>,
Dan Williams <dan.j.williams@...el.com>,
Stephen Bates <sbates@...thlin.com>,
Jakowski Andrzej <andrzej.jakowski@...el.com>,
Christoph Hellwig <hch@....de>,
Xiong Jianxin <jianxin.xiong@...el.com>
Subject: Re: [RFC PATCH v2 06/11] dma-direct: Support PCI P2PDMA pages in
dma-direct map_sg
On Fri, Mar 12, 2021 at 11:27:46AM -0700, Logan Gunthorpe wrote:
> So then we reject the patches that make that change. Seems like an odd
> argument to say that we can't do something that won't cause problems
> because someone might use it as an example and do something that will
> cause problems. Reject the change that causes the problem.
No, the problem is a mess of calling conventions. A calling convention
returning 0 for error, positive values for success is fine. One returning
a negative errno for error and positive values for success is fine a well.
One returning 0 for the usual errors and negativ errnos for an unusual
corner case is just a complete mess.
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