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5e180ff326
Add pci_p2pdma_map_segment() as a helper for dma_map_sg() implementations. It takes an scatterlist segment that must point to a pci_p2pdma struct page and will map it if the mapping requires a bus address. The return value indicates whether the mapping required a bus address or whether the caller still needs to map the segment normally. If the segment should not be mapped, -EREMOTEIO is returned. This helper uses a state structure to track the changes to the pgmap across calls and avoid needing to lookup into the xarray for every page. The prototype for the helper is added to dma-map-ops.h as it is only useful to dma map implementations and don't need to pollute the public pci-p2pdma header. Signed-off-by: Logan Gunthorpe <logang@deltatee.com> Acked-by: Bjorn Helgaas <bhelgaas@google.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Christoph Hellwig <hch@lst.de>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.