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Date: Tue, 29 Jul 2025 09:52:30 +0200
From: Christoph Hellwig <hch@lst.de>
To: Leon Romanovsky <leon@kernel.org>
Cc: Christoph Hellwig <hch@lst.de>,
	Alex Williamson <alex.williamson@redhat.com>,
	Jason Gunthorpe <jgg@nvidia.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Bjorn Helgaas <bhelgaas@google.com>,
	Christian =?iso-8859-1?Q?K=F6nig?= <christian.koenig@amd.com>,
	dri-devel@lists.freedesktop.org, iommu@lists.linux.dev,
	Jens Axboe <axboe@kernel.dk>,
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	Logan Gunthorpe <logang@deltatee.com>,
	Marek Szyprowski <m.szyprowski@samsung.com>,
	Robin Murphy <robin.murphy@arm.com>,
	Sumit Semwal <sumit.semwal@linaro.org>,
	Vivek Kasireddy <vivek.kasireddy@intel.com>,
	Will Deacon <will@kernel.org>
Subject: Re: [PATCH 05/10] PCI/P2PDMA: Export pci_p2pdma_map_type() function
Message-ID: <20250729075230.GB23823@lst.de>
References: <cover.1753274085.git.leonro@nvidia.com> <82e62eb59afcd39b68ae143573d5ed113a92344e.1753274085.git.leonro@nvidia.com> <20250724080313.GA31887@lst.de> <20250724081321.GT402218@unreal>
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In-Reply-To: <20250724081321.GT402218@unreal>
User-Agent: Mutt/1.5.17 (2007-11-01)

On Thu, Jul 24, 2025 at 11:13:21AM +0300, Leon Romanovsky wrote:
> On Thu, Jul 24, 2025 at 10:03:13AM +0200, Christoph Hellwig wrote:
> > On Wed, Jul 23, 2025 at 04:00:06PM +0300, Leon Romanovsky wrote:
> > > From: Leon Romanovsky <leonro@nvidia.com>
> > > 
> > > Export the pci_p2pdma_map_type() function to allow external modules
> > > and subsystems to determine the appropriate mapping type for P2PDMA
> > > transfers between a provider and target device.
> > 
> > External modules have no business doing this.
> 
> VFIO PCI code is built as module. There is no way to access PCI p2p code
> without exporting functions in it.

We never ever export anything for "external" modules, and you really
should know that.