From: hch@lst.de (Christoph Hellwig)
Subject: [PATCH v2 03/14] PCI/P2PDMA: Add constants for not-supported result upstream_bridge_distance()
Date: Thu, 8 Aug 2019 09:31:09 +0200 [thread overview]
Message-ID: <20190808073109.GC29852@lst.de> (raw)
In-Reply-To: <4b0c012a-c3a1-a1c0-b098-8b350963aed1@deltatee.com>
On Wed, Aug 07, 2019@09:58:06AM -0600, Logan Gunthorpe wrote:
> We only calculate it at the same time as we calculate the distance. This
> is necessary because, to calculate the type, we have to walk the tree
> and check the ACS bits. If we separated it, we'd have to walk the tree
> twice in a very similar way just to determine both the distance and the
> mapping type.
Calculating it together makes perfect sense. What I find odd is the
overloading of a single return value. Why not return the map type as
the return value, and the distance as a by reference argument to keep
them properly separated?
WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch@lst.de>
To: Logan Gunthorpe <logang@deltatee.com>
Cc: Christoph Hellwig <hch@lst.de>,
linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org,
linux-nvme@lists.infradead.org, linux-rdma@vger.kernel.org,
Bjorn Helgaas <bhelgaas@google.com>,
Christian Koenig <Christian.Koenig@amd.com>,
Jason Gunthorpe <jgg@mellanox.com>,
Sagi Grimberg <sagi@grimberg.me>, Keith Busch <kbusch@kernel.org>,
Jens Axboe <axboe@fb.com>,
Dan Williams <dan.j.williams@intel.com>,
Eric Pilmore <epilmore@gigaio.com>,
Stephen Bates <sbates@raithlin.com>
Subject: Re: [PATCH v2 03/14] PCI/P2PDMA: Add constants for not-supported result upstream_bridge_distance()
Date: Thu, 8 Aug 2019 09:31:09 +0200 [thread overview]
Message-ID: <20190808073109.GC29852@lst.de> (raw)
In-Reply-To: <4b0c012a-c3a1-a1c0-b098-8b350963aed1@deltatee.com>
On Wed, Aug 07, 2019 at 09:58:06AM -0600, Logan Gunthorpe wrote:
> We only calculate it at the same time as we calculate the distance. This
> is necessary because, to calculate the type, we have to walk the tree
> and check the ACS bits. If we separated it, we'd have to walk the tree
> twice in a very similar way just to determine both the distance and the
> mapping type.
Calculating it together makes perfect sense. What I find odd is the
overloading of a single return value. Why not return the map type as
the return value, and the distance as a by reference argument to keep
them properly separated?
next prev parent reply other threads:[~2019-08-08 7:31 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-30 16:35 [PATCH v2 00/14] PCI/P2PDMA: Support transactions that hit the host bridge Logan Gunthorpe
2019-07-30 16:35 ` Logan Gunthorpe
2019-07-30 16:35 ` [PATCH v2 01/14] PCI/P2PDMA: Introduce private pagemap structure Logan Gunthorpe
2019-07-30 16:35 ` Logan Gunthorpe
2019-07-30 16:35 ` [PATCH v2 02/14] PCI/P2PDMA: Add the provider's pci_dev to the pci_p2pdma_pagemap struct Logan Gunthorpe
2019-07-30 16:35 ` Logan Gunthorpe
2019-07-30 16:35 ` [PATCH v2 03/14] PCI/P2PDMA: Add constants for not-supported result upstream_bridge_distance() Logan Gunthorpe
2019-07-30 16:35 ` Logan Gunthorpe
2019-08-07 5:54 ` Christoph Hellwig
2019-08-07 5:54 ` Christoph Hellwig
2019-08-07 15:58 ` Logan Gunthorpe
2019-08-07 15:58 ` Logan Gunthorpe
2019-08-08 7:31 ` Christoph Hellwig [this message]
2019-08-08 7:31 ` Christoph Hellwig
2019-08-08 15:58 ` Logan Gunthorpe
2019-08-08 15:58 ` Logan Gunthorpe
2019-07-30 16:35 ` [PATCH v2 04/14] PCI/P2PDMA: Factor out __upstream_bridge_distance() Logan Gunthorpe
2019-07-30 16:35 ` Logan Gunthorpe
2019-07-30 16:35 ` [PATCH v2 05/14] PCI/P2PDMA: Apply host bridge white list for ACS Logan Gunthorpe
2019-07-30 16:35 ` Logan Gunthorpe
2019-07-30 16:35 ` [PATCH v2 06/14] PCI/P2PDMA: Factor out host_bridge_whitelist() Logan Gunthorpe
2019-07-30 16:35 ` Logan Gunthorpe
2019-07-30 16:35 ` [PATCH v2 07/14] PCI/P2PDMA: Add whitelist support for Intel Host Bridges Logan Gunthorpe
2019-07-30 16:35 ` Logan Gunthorpe
2019-07-30 16:35 ` [PATCH v2 08/14] PCI/P2PDMA: Add attrs argument to pci_p2pdma_map_sg() Logan Gunthorpe
2019-07-30 16:35 ` Logan Gunthorpe
2019-07-30 16:35 ` [PATCH v2 09/14] PCI/P2PDMA: Introduce pci_p2pdma_unmap_sg() Logan Gunthorpe
2019-07-30 16:35 ` Logan Gunthorpe
2019-07-30 16:35 ` [PATCH v2 10/14] PCI/P2PDMA: Factor out __pci_p2pdma_map_sg() Logan Gunthorpe
2019-07-30 16:35 ` Logan Gunthorpe
2019-07-30 16:35 ` [PATCH v2 11/14] PCI/P2PDMA: Store mapping method in an xarray Logan Gunthorpe
2019-07-30 16:35 ` Logan Gunthorpe
2019-08-07 5:59 ` Christoph Hellwig
2019-08-07 5:59 ` Christoph Hellwig
2019-07-30 16:35 ` [PATCH v2 12/14] PCI/P2PDMA: dma_map P2PDMA map requests that traverse the host bridge Logan Gunthorpe
2019-07-30 16:35 ` Logan Gunthorpe
2019-07-30 16:35 ` [PATCH v2 13/14] PCI/P2PDMA: No longer require no-mmu for host bridge whitelist Logan Gunthorpe
2019-07-30 16:35 ` Logan Gunthorpe
2019-08-07 5:59 ` Christoph Hellwig
2019-08-07 5:59 ` Christoph Hellwig
2019-08-07 12:43 ` Bjorn Helgaas
2019-08-07 12:43 ` Bjorn Helgaas
2019-08-08 7:29 ` Christoph Hellwig
2019-08-08 7:29 ` Christoph Hellwig
2019-07-30 16:35 ` [PATCH v2 14/14] PCI/P2PDMA: Update documentation for pci_p2pdma_distance_many() Logan Gunthorpe
2019-07-30 16:35 ` Logan Gunthorpe
2019-08-06 23:44 ` [PATCH v2 00/14] PCI/P2PDMA: Support transactions that hit the host bridge Bjorn Helgaas
2019-08-06 23:44 ` Bjorn Helgaas
2019-08-07 0:31 ` Logan Gunthorpe
2019-08-07 0:31 ` Logan Gunthorpe
2019-08-07 19:29 ` Bjorn Helgaas
2019-08-07 19:29 ` Bjorn Helgaas
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