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From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Christoph Hellwig <hch@lst.de>
Cc: "Logan Gunthorpe" <logang@deltatee.com>,
	"Jason Gunthorpe" <jgg@ziepe.ca>,
	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,
	"Stephen Bates" <sbates@raithlin.com>,
	"Dan Williams" <dan.j.williams@intel.com>,
	"Christian König" <christian.koenig@amd.com>,
	"John Hubbard" <jhubbard@nvidia.com>,
	"Don Dutile" <ddutile@redhat.com>,
	"Matthew Wilcox" <willy@infradead.org>,
	"Daniel Vetter" <daniel.vetter@ffwll.ch>,
	"Minturn Dave B" <dave.b.minturn@intel.com>,
	"Jason Ekstrand" <jason@jlekstrand.net>,
	"Dave Hansen" <dave.hansen@linux.intel.com>,
	"Xiong Jianxin" <jianxin.xiong@intel.com>,
	"Bjorn Helgaas" <helgaas@kernel.org>,
	"Ira Weiny" <ira.weiny@intel.com>,
	"Robin Murphy" <robin.murphy@arm.com>,
	"Martin Oliveira" <martin.oliveira@eideticom.com>,
	"Chaitanya Kulkarni" <ckulkarnilinux@gmail.com>,
	"Ralph Campbell" <rcampbell@nvidia.com>,
	"Bjorn Helgaas" <bhelgaas@google.com>
Subject: Re: [PATCH v7 20/21] PCI/P2PDMA: Introduce pci_mmap_p2pmem()
Date: Wed, 6 Jul 2022 09:04:41 +0200	[thread overview]
Message-ID: <YsU0Cb0rRbW8FGPX@kroah.com> (raw)
In-Reply-To: <20220706065127.GA27132@lst.de>

On Wed, Jul 06, 2022 at 08:51:27AM +0200, Christoph Hellwig wrote:
> On Tue, Jul 05, 2022 at 12:16:45PM -0600, Logan Gunthorpe wrote:
> > The current version does it through a char device, but that requires
> > creating a simple_fs and anon_inode for teardown on driver removal, plus
> > a bunch of hooks through the driver that exposes it (NVMe, in this case)
> > to set this all up.
> > 
> > Christoph is suggesting a sysfs interface which could potentially avoid
> > the anon_inode and all of the extra hooks. It has some significant
> > benefits and maybe some small downsides, but I wouldn't describe it as
> > horrid.
> 
> Yeah, I don't think is is horrible, it fits in with the resource files
> for the BARs, and solves a lot of problems.  Greg, can you explain
> what would be so bad about it?

As you mention, you will have to pass different things down into sysfs
in order for that to be possible.  If it matches the resource files like
we currently have today, that might not be that bad, but it still feels
odd to me.  Let's see an implementation and a Documentation/ABI/ entry
first though.

thanks,

greg k-h

  reply	other threads:[~2022-07-06  7:05 UTC|newest]

Thread overview: 71+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-06-15 16:12 [PATCH v7 00/21] Userspace P2PDMA with O_DIRECT NVMe devices Logan Gunthorpe
2022-06-15 16:12 ` [PATCH v7 01/21] lib/scatterlist: add flag for indicating P2PDMA segments in an SGL Logan Gunthorpe
2022-06-29  6:33   ` Christoph Hellwig
2022-06-29  9:05   ` Robin Murphy
2022-06-29 15:39     ` Logan Gunthorpe
2022-06-29 18:02       ` Robin Murphy
2022-06-29 18:24         ` Logan Gunthorpe
2022-07-04 15:08   ` Robin Murphy
2022-06-15 16:12 ` [PATCH v7 02/21] PCI/P2PDMA: Attempt to set map_type if it has not been set Logan Gunthorpe
2022-06-29  6:33   ` Christoph Hellwig
2022-06-15 16:12 ` [PATCH v7 03/21] PCI/P2PDMA: Expose pci_p2pdma_map_type() Logan Gunthorpe
2022-06-29  6:39   ` Christoph Hellwig
2022-06-15 16:12 ` [PATCH v7 04/21] PCI/P2PDMA: Introduce helpers for dma_map_sg implementations Logan Gunthorpe
2022-06-29  6:39   ` Christoph Hellwig
2022-06-15 16:12 ` [PATCH v7 05/21] dma-mapping: allow EREMOTEIO return code for P2PDMA transfers Logan Gunthorpe
2022-06-29  6:40   ` Christoph Hellwig
2022-06-15 16:12 ` [PATCH v7 06/21] dma-direct: support PCI P2PDMA pages in dma-direct map_sg Logan Gunthorpe
2022-06-29  6:40   ` Christoph Hellwig
2022-06-15 16:12 ` [PATCH v7 07/21] dma-mapping: add flags to dma_map_ops to indicate PCI P2PDMA support Logan Gunthorpe
2022-06-29  6:41   ` Christoph Hellwig
2022-06-15 16:12 ` [PATCH v7 08/21] iommu/dma: support PCI P2PDMA pages in dma-iommu map_sg Logan Gunthorpe
2022-06-29 12:07   ` Robin Murphy
2022-06-29 15:57     ` Logan Gunthorpe
2022-06-29 19:15       ` Robin Murphy
2022-06-29 22:41         ` Logan Gunthorpe
2022-06-30 14:56           ` Robin Murphy
2022-06-30 21:21             ` Logan Gunthorpe
2022-06-15 16:12 ` [PATCH v7 09/21] nvme-pci: check DMA ops when indicating support for PCI P2PDMA Logan Gunthorpe
2022-06-29  6:41   ` Christoph Hellwig
2022-06-15 16:12 ` [PATCH v7 10/21] nvme-pci: convert to using dma_map_sgtable() Logan Gunthorpe
2022-06-29  6:42   ` Christoph Hellwig
2022-06-15 16:12 ` [PATCH v7 11/21] RDMA/core: introduce ib_dma_pci_p2p_dma_supported() Logan Gunthorpe
2022-06-29  6:42   ` Christoph Hellwig
2022-06-15 16:12 ` [PATCH v7 12/21] RDMA/rw: drop pci_p2pdma_[un]map_sg() Logan Gunthorpe
2022-06-29  6:42   ` Christoph Hellwig
2022-06-15 16:12 ` [PATCH v7 13/21] PCI/P2PDMA: Remove pci_p2pdma_[un]map_sg() Logan Gunthorpe
2022-06-29  6:43   ` Christoph Hellwig
2022-06-15 16:12 ` [PATCH v7 14/21] mm: introduce FOLL_PCI_P2PDMA to gate getting PCI P2PDMA pages Logan Gunthorpe
2022-06-29  6:45   ` Christoph Hellwig
2022-06-15 16:12 ` [PATCH v7 15/21] iov_iter: introduce iov_iter_get_pages_[alloc_]flags() Logan Gunthorpe
2022-06-29  6:45   ` Christoph Hellwig
2022-06-15 16:12 ` [PATCH v7 16/21] block: add check when merging zone device pages Logan Gunthorpe
2022-06-29  6:46   ` Christoph Hellwig
2022-06-29 16:06     ` Logan Gunthorpe
2022-06-30 21:50       ` Logan Gunthorpe
2022-07-04  6:07         ` Christoph Hellwig
2022-06-15 16:12 ` [PATCH v7 17/21] lib/scatterlist: " Logan Gunthorpe
2022-06-15 16:12 ` [PATCH v7 18/21] block: set FOLL_PCI_P2PDMA in __bio_iov_iter_get_pages() Logan Gunthorpe
2022-06-15 16:12 ` [PATCH v7 19/21] block: set FOLL_PCI_P2PDMA in bio_map_user_iov() Logan Gunthorpe
2022-06-15 16:12 ` [PATCH v7 20/21] PCI/P2PDMA: Introduce pci_mmap_p2pmem() Logan Gunthorpe
2022-06-29  6:48   ` Christoph Hellwig
2022-06-29 16:00     ` Logan Gunthorpe
2022-06-29 17:59       ` Jason Gunthorpe
2022-07-05  7:51         ` Christoph Hellwig
2022-07-05 13:51           ` Jason Gunthorpe
2022-07-05 16:12             ` Christoph Hellwig
2022-07-05 16:29               ` Jason Gunthorpe
2022-07-05 16:40                 ` Christoph Hellwig
2022-07-05 16:41               ` Logan Gunthorpe
2022-07-05 16:43                 ` Christoph Hellwig
2022-07-05 16:44                   ` Logan Gunthorpe
2022-07-05 16:50                     ` Christoph Hellwig
2022-07-05 17:21                       ` Greg Kroah-Hartman
2022-07-05 17:32                         ` Logan Gunthorpe
2022-07-05 17:42                           ` Greg Kroah-Hartman
2022-07-05 18:16                             ` Logan Gunthorpe
2022-07-06  6:51                               ` Christoph Hellwig
2022-07-06  7:04                                 ` Greg Kroah-Hartman [this message]
2022-07-06 21:30                                   ` Logan Gunthorpe
2022-06-15 16:12 ` [PATCH v7 21/21] nvme-pci: allow mmaping the CMB in userspace Logan Gunthorpe
2022-06-29  6:49 ` [PATCH v7 00/21] Userspace P2PDMA with O_DIRECT NVMe devices Christoph Hellwig

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