Messages in this thread | | | Date | Fri, 12 Mar 2021 17:38:56 -0800 | From | Ira Weiny <> | Subject | Re: [RFC PATCH v2 04/11] PCI/P2PDMA: Introduce pci_p2pdma_should_map_bus() and pci_p2pdma_bus_offset() |
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On Thu, Mar 11, 2021 at 04:31:34PM -0700, Logan Gunthorpe wrote: > Introduce pci_p2pdma_should_map_bus() which is meant to be called by > DMA map functions to determine how to map a given p2pdma page. > > pci_p2pdma_bus_offset() is also added to allow callers to get the bus > offset if they need to map the bus address. > > Signed-off-by: Logan Gunthorpe <logang@deltatee.com> > --- > drivers/pci/p2pdma.c | 50 ++++++++++++++++++++++++++++++++++++++ > include/linux/pci-p2pdma.h | 11 +++++++++ > 2 files changed, 61 insertions(+) > > diff --git a/drivers/pci/p2pdma.c b/drivers/pci/p2pdma.c > index 7f6836732bce..66d16b7eb668 100644 > --- a/drivers/pci/p2pdma.c > +++ b/drivers/pci/p2pdma.c > @@ -912,6 +912,56 @@ void pci_p2pdma_unmap_sg_attrs(struct device *dev, struct scatterlist *sg, > } > EXPORT_SYMBOL_GPL(pci_p2pdma_unmap_sg_attrs); > > +/** > + * pci_p2pdma_bus_offset - returns the bus offset for a given page > + * @page: page to get the offset for > + * > + * Must be passed a PCI p2pdma page. > + */ > +u64 pci_p2pdma_bus_offset(struct page *page) > +{ > + struct pci_p2pdma_pagemap *p2p_pgmap = to_p2p_pgmap(page->pgmap); > + > + WARN_ON(!is_pci_p2pdma_page(page));
Shouldn't this check be before the to_p2p_pgmap() call? And I've been told not to introduce WARN_ON's. Should this be?
if (!is_pci_p2pdma_page(page)) return -1;
???
Ira
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