From: Christoph Hellwig <hch@lst.de>
To: Robin Murphy <robin.murphy@arm.com>
Cc: "Logan Gunthorpe" <logang@deltatee.com>,
linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org,
linux-block@vger.kernel.org, linux-pci@vger.kernel.org,
linux-mm@kvack.org, iommu@lists.linux-foundation.org,
"Minturn Dave B" <dave.b.minturn@intel.com>,
"John Hubbard" <jhubbard@nvidia.com>,
"Dave Hansen" <dave.hansen@linux.intel.com>,
"Matthew Wilcox" <willy@infradead.org>,
"Christian König" <christian.koenig@amd.com>,
"Jason Gunthorpe" <jgg@ziepe.ca>,
"Jason Ekstrand" <jason@jlekstrand.net>,
"Daniel Vetter" <daniel.vetter@ffwll.ch>,
"Dan Williams" <dan.j.williams@intel.com>,
"Stephen Bates" <sbates@raithlin.com>,
"Jakowski Andrzej" <andrzej.jakowski@intel.com>,
"Christoph Hellwig" <hch@lst.de>,
"Xiong Jianxin" <jianxin.xiong@intel.com>
Subject: Re: [RFC PATCH v2 06/11] dma-direct: Support PCI P2PDMA pages in dma-direct map_sg
Date: Tue, 16 Mar 2021 08:56:58 +0100 [thread overview]
Message-ID: <20210316075658.GA15949@lst.de> (raw)
In-Reply-To: <a8205c02-a43f-d4e8-a9fe-5963df3a7b40@arm.com>
On Fri, Mar 12, 2021 at 06:11:17PM +0000, Robin Murphy wrote:
> Sure, that's how things stand immediately after this patch. But then
> someone comes along with the perfectly reasonable argument for returning
> more expressive error information for regular mapping failures as well
> (because sometimes those can be terminal too, as above), we start to get
> divergent behaviour across architectures and random bits of old code subtly
> breaking down the line. *That* is what makes me wary of making a
> fundamental change to a long-standing "nonzero means success" interface...
Agreed. IMHO dma_map_sg actually needs to be switched to return
unsigned to help root this out, going the other way is no helpful.
WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch@lst.de>
To: Robin Murphy <robin.murphy@arm.com>
Cc: "Logan Gunthorpe" <logang@deltatee.com>,
linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org,
linux-block@vger.kernel.org, linux-pci@vger.kernel.org,
linux-mm@kvack.org, iommu@lists.linux-foundation.org,
"Minturn Dave B" <dave.b.minturn@intel.com>,
"John Hubbard" <jhubbard@nvidia.com>,
"Dave Hansen" <dave.hansen@linux.intel.com>,
"Matthew Wilcox" <willy@infradead.org>,
"Christian König" <christian.koenig@amd.com>,
"Jason Gunthorpe" <jgg@ziepe.ca>,
"Jason Ekstrand" <jason@jlekstrand.net>,
"Daniel Vetter" <daniel.vetter@ffwll.ch>,
"Dan Williams" <dan.j.williams@intel.com>,
"Stephen Bates" <sbates@raithlin.com>,
"Jakowski Andrzej" <andrzej.jakowski@intel.com>,
"Christoph Hellwig" <hch@lst.de>,
"Xiong Jianxin" <jianxin.xiong@intel.com>
Subject: Re: [RFC PATCH v2 06/11] dma-direct: Support PCI P2PDMA pages in dma-direct map_sg
Date: Tue, 16 Mar 2021 08:56:58 +0100 [thread overview]
Message-ID: <20210316075658.GA15949@lst.de> (raw)
In-Reply-To: <a8205c02-a43f-d4e8-a9fe-5963df3a7b40@arm.com>
On Fri, Mar 12, 2021 at 06:11:17PM +0000, Robin Murphy wrote:
> Sure, that's how things stand immediately after this patch. But then
> someone comes along with the perfectly reasonable argument for returning
> more expressive error information for regular mapping failures as well
> (because sometimes those can be terminal too, as above), we start to get
> divergent behaviour across architectures and random bits of old code subtly
> breaking down the line. *That* is what makes me wary of making a
> fundamental change to a long-standing "nonzero means success" interface...
Agreed. IMHO dma_map_sg actually needs to be switched to return
unsigned to help root this out, going the other way is no helpful.
_______________________________________________
Linux-nvme mailing list
Linux-nvme@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-nvme
WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch@lst.de>
To: Robin Murphy <robin.murphy@arm.com>
Cc: "Minturn Dave B" <dave.b.minturn@intel.com>,
"Jason Gunthorpe" <jgg@ziepe.ca>,
"Jakowski Andrzej" <andrzej.jakowski@intel.com>,
linux-pci@vger.kernel.org,
"Daniel Vetter" <daniel.vetter@ffwll.ch>,
"Dave Hansen" <dave.hansen@linux.intel.com>,
linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org,
"Stephen Bates" <sbates@raithlin.com>,
linux-block@vger.kernel.org, linux-mm@kvack.org,
iommu@lists.linux-foundation.org,
"Christoph Hellwig" <hch@lst.de>,
"Matthew Wilcox" <willy@infradead.org>,
"Jason Ekstrand" <jason@jlekstrand.net>,
"John Hubbard" <jhubbard@nvidia.com>,
"Dan Williams" <dan.j.williams@intel.com>,
"Logan Gunthorpe" <logang@deltatee.com>,
"Christian König" <christian.koenig@amd.com>,
"Xiong Jianxin" <jianxin.xiong@intel.com>
Subject: Re: [RFC PATCH v2 06/11] dma-direct: Support PCI P2PDMA pages in dma-direct map_sg
Date: Tue, 16 Mar 2021 08:56:58 +0100 [thread overview]
Message-ID: <20210316075658.GA15949@lst.de> (raw)
In-Reply-To: <a8205c02-a43f-d4e8-a9fe-5963df3a7b40@arm.com>
On Fri, Mar 12, 2021 at 06:11:17PM +0000, Robin Murphy wrote:
> Sure, that's how things stand immediately after this patch. But then
> someone comes along with the perfectly reasonable argument for returning
> more expressive error information for regular mapping failures as well
> (because sometimes those can be terminal too, as above), we start to get
> divergent behaviour across architectures and random bits of old code subtly
> breaking down the line. *That* is what makes me wary of making a
> fundamental change to a long-standing "nonzero means success" interface...
Agreed. IMHO dma_map_sg actually needs to be switched to return
unsigned to help root this out, going the other way is no helpful.
_______________________________________________
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu
next prev parent reply other threads:[~2021-03-16 7:58 UTC|newest]
Thread overview: 141+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-11 23:31 [RFC PATCH v2 00/11] Add support to dma_map_sg for P2PDMA Logan Gunthorpe
2021-03-11 23:31 ` Logan Gunthorpe
2021-03-11 23:31 ` Logan Gunthorpe
2021-03-11 23:31 ` [RFC PATCH v2 01/11] PCI/P2PDMA: Pass gfp_mask flags to upstream_bridge_distance_warn() Logan Gunthorpe
2021-03-11 23:31 ` Logan Gunthorpe
2021-03-11 23:31 ` Logan Gunthorpe
2021-03-12 20:39 ` Bjorn Helgaas
2021-03-12 20:39 ` Bjorn Helgaas
2021-03-12 20:39 ` Bjorn Helgaas
2021-03-12 20:53 ` Logan Gunthorpe
2021-03-12 20:53 ` Logan Gunthorpe
2021-03-12 20:53 ` Logan Gunthorpe
2021-03-11 23:31 ` [RFC PATCH v2 02/11] PCI/P2PDMA: Avoid pci_get_slot() which sleeps Logan Gunthorpe
2021-03-11 23:31 ` Logan Gunthorpe
2021-03-11 23:31 ` Logan Gunthorpe
2021-03-12 20:57 ` Bjorn Helgaas
2021-03-12 20:57 ` Bjorn Helgaas
2021-03-12 20:57 ` Bjorn Helgaas
2021-03-12 21:37 ` Logan Gunthorpe
2021-03-12 21:37 ` Logan Gunthorpe
2021-03-12 21:37 ` Logan Gunthorpe
2021-03-11 23:31 ` [RFC PATCH v2 03/11] PCI/P2PDMA: Attempt to set map_type if it has not been set Logan Gunthorpe
2021-03-11 23:31 ` Logan Gunthorpe
2021-03-11 23:31 ` Logan Gunthorpe
2021-03-11 23:31 ` [RFC PATCH v2 04/11] PCI/P2PDMA: Introduce pci_p2pdma_should_map_bus() and pci_p2pdma_bus_offset() Logan Gunthorpe
2021-03-11 23:31 ` Logan Gunthorpe
2021-03-11 23:31 ` Logan Gunthorpe
2021-03-13 1:38 ` Ira Weiny
2021-03-13 1:38 ` Ira Weiny
2021-03-13 1:38 ` Ira Weiny
2021-03-15 16:27 ` Logan Gunthorpe
2021-03-15 16:27 ` Logan Gunthorpe
2021-03-15 16:27 ` Logan Gunthorpe
2021-03-24 17:21 ` Jason Gunthorpe
2021-03-24 17:21 ` Jason Gunthorpe
2021-03-24 17:21 ` Jason Gunthorpe
2021-03-24 18:34 ` Christian König
2021-03-24 18:34 ` Christian König
2021-03-24 18:34 ` Christian König
2021-03-13 2:32 ` Ira Weiny
2021-03-13 2:32 ` Ira Weiny
2021-03-13 2:32 ` Ira Weiny
2021-03-15 16:30 ` Logan Gunthorpe
2021-03-15 16:30 ` Logan Gunthorpe
2021-03-15 16:30 ` Logan Gunthorpe
2021-03-16 8:14 ` Christoph Hellwig
2021-03-16 8:14 ` Christoph Hellwig
2021-03-16 8:14 ` Christoph Hellwig
2021-03-11 23:31 ` [RFC PATCH v2 05/11] lib/scatterlist: Add flag for indicating P2PDMA segments in an SGL Logan Gunthorpe
2021-03-11 23:31 ` Logan Gunthorpe
2021-03-11 23:31 ` Logan Gunthorpe
2021-03-11 23:31 ` [RFC PATCH v2 06/11] dma-direct: Support PCI P2PDMA pages in dma-direct map_sg Logan Gunthorpe
2021-03-11 23:31 ` Logan Gunthorpe
2021-03-11 23:31 ` Logan Gunthorpe
2021-03-12 15:52 ` Robin Murphy
2021-03-12 15:52 ` Robin Murphy
2021-03-12 15:52 ` Robin Murphy
2021-03-12 16:24 ` Logan Gunthorpe
2021-03-12 16:24 ` Logan Gunthorpe
2021-03-12 16:24 ` Logan Gunthorpe
2021-03-12 18:11 ` Robin Murphy
2021-03-12 18:11 ` Robin Murphy
2021-03-12 18:11 ` Robin Murphy
2021-03-12 18:27 ` Logan Gunthorpe
2021-03-12 18:27 ` Logan Gunthorpe
2021-03-12 18:27 ` Logan Gunthorpe
2021-03-16 7:58 ` Christoph Hellwig
2021-03-16 7:58 ` Christoph Hellwig
2021-03-16 7:58 ` Christoph Hellwig
2021-03-16 15:54 ` Logan Gunthorpe
2021-03-16 15:54 ` Logan Gunthorpe
2021-03-16 15:54 ` Logan Gunthorpe
2021-03-16 7:56 ` Christoph Hellwig [this message]
2021-03-16 7:56 ` Christoph Hellwig
2021-03-16 7:56 ` Christoph Hellwig
2021-03-16 8:11 ` Christoph Hellwig
2021-03-16 8:11 ` Christoph Hellwig
2021-03-16 8:11 ` Christoph Hellwig
2021-03-11 23:31 ` [RFC PATCH v2 07/11] dma-mapping: Add flags to dma_map_ops to indicate PCI P2PDMA support Logan Gunthorpe
2021-03-11 23:31 ` Logan Gunthorpe
2021-03-11 23:31 ` Logan Gunthorpe
2021-03-13 2:36 ` Ira Weiny
2021-03-13 2:36 ` Ira Weiny
2021-03-13 2:36 ` Ira Weiny
2021-03-15 16:33 ` Logan Gunthorpe
2021-03-15 16:33 ` Logan Gunthorpe
2021-03-15 16:33 ` Logan Gunthorpe
2021-03-16 8:00 ` Christoph Hellwig
2021-03-16 8:00 ` Christoph Hellwig
2021-03-16 8:00 ` Christoph Hellwig
2021-03-16 8:15 ` Christoph Hellwig
2021-03-16 8:15 ` Christoph Hellwig
2021-03-16 8:15 ` Christoph Hellwig
2021-03-11 23:31 ` [RFC PATCH v2 08/11] iommu/dma: Support PCI P2PDMA pages in dma-iommu map_sg Logan Gunthorpe
2021-03-11 23:31 ` Logan Gunthorpe
2021-03-11 23:31 ` Logan Gunthorpe
2021-03-12 15:52 ` Robin Murphy
2021-03-12 15:52 ` Robin Murphy
2021-03-12 15:52 ` Robin Murphy
2021-03-12 17:03 ` Logan Gunthorpe
2021-03-12 17:03 ` Logan Gunthorpe
2021-03-12 17:03 ` Logan Gunthorpe
2021-03-12 19:47 ` Robin Murphy
2021-03-12 19:47 ` Robin Murphy
2021-03-12 19:47 ` Robin Murphy
2021-03-12 20:06 ` Logan Gunthorpe
2021-03-12 20:06 ` Logan Gunthorpe
2021-03-12 20:06 ` Logan Gunthorpe
2021-03-11 23:31 ` [RFC PATCH v2 09/11] block: Add BLK_STS_P2PDMA Logan Gunthorpe
2021-03-11 23:31 ` Logan Gunthorpe
2021-03-11 23:31 ` Logan Gunthorpe
2021-03-16 8:00 ` Christoph Hellwig
2021-03-16 8:00 ` Christoph Hellwig
2021-03-16 8:00 ` Christoph Hellwig
2021-03-16 16:02 ` Logan Gunthorpe
2021-03-16 16:02 ` Logan Gunthorpe
2021-03-16 16:02 ` Logan Gunthorpe
2021-03-11 23:31 ` [RFC PATCH v2 10/11] nvme-pci: Check DMA ops when indicating support for PCI P2PDMA Logan Gunthorpe
2021-03-11 23:31 ` Logan Gunthorpe
2021-03-11 23:31 ` Logan Gunthorpe
2021-03-11 23:31 ` [RFC PATCH v2 11/11] nvme-pci: Convert to using dma_map_sg for p2pdma pages Logan Gunthorpe
2021-03-11 23:31 ` Logan Gunthorpe
2021-03-11 23:31 ` Logan Gunthorpe
2021-03-11 23:59 ` Jason Gunthorpe
2021-03-11 23:59 ` Jason Gunthorpe
2021-03-11 23:59 ` Jason Gunthorpe
2021-03-12 1:37 ` Logan Gunthorpe
2021-03-12 1:37 ` Logan Gunthorpe
2021-03-12 1:37 ` Logan Gunthorpe
2021-03-12 15:51 ` [RFC PATCH v2 00/11] Add support to dma_map_sg for P2PDMA Robin Murphy
2021-03-12 15:51 ` Robin Murphy
2021-03-12 15:51 ` Robin Murphy
2021-03-12 16:18 ` Logan Gunthorpe
2021-03-12 16:18 ` Logan Gunthorpe
2021-03-12 16:18 ` Logan Gunthorpe
2021-03-12 17:46 ` Robin Murphy
2021-03-12 17:46 ` Robin Murphy
2021-03-12 17:46 ` Robin Murphy
2021-03-12 18:24 ` Logan Gunthorpe
2021-03-12 18:24 ` Logan Gunthorpe
2021-03-12 18:24 ` Logan Gunthorpe
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