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[RFC,02/15] PCI/P2PDMA: Attempt to set map_type if it has not been set

Message ID 20201106170036.18713-3-logang@deltatee.com
State New
Headers show
Series Userspace P2PDMA with O_DIRECT NVMe devices | expand

Commit Message

Logan Gunthorpe Nov. 6, 2020, 5 p.m. UTC
Attempt to find the mapping type for P2PDMA pages on the first
DMA map attempt if it has not been done ahead of time.

Previously, the mapping type was expected to be calculated ahead of
time, but if pages are to come from userspace then there's no
way to ensure the path was checked ahead of time.

Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
 drivers/pci/p2pdma.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)
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diff --git a/drivers/pci/p2pdma.c b/drivers/pci/p2pdma.c
index 94583779c36e..ea8472278b11 100644
--- a/drivers/pci/p2pdma.c
+++ b/drivers/pci/p2pdma.c
@@ -824,11 +824,17 @@  EXPORT_SYMBOL_GPL(pci_p2pmem_publish);
 static enum pci_p2pdma_map_type pci_p2pdma_map_type(struct pci_dev *provider,
 						    struct pci_dev *client)
+	enum pci_p2pdma_map_type ret;
 	if (!provider->p2pdma)
-	return xa_to_value(xa_load(&provider->p2pdma->map_types,
-				   map_types_idx(client)));
+	ret = xa_to_value(xa_load(&provider->p2pdma->map_types,
+				  map_types_idx(client)));
+	if (ret != PCI_P2PDMA_MAP_UNKNOWN)
+		return ret;
+	return upstream_bridge_distance_warn(provider, client, NULL);
 static int __pci_p2pdma_map_sg(struct pci_p2pdma_pagemap *p2p_pgmap,
@@ -890,7 +896,6 @@  int pci_p2pdma_map_sg_attrs(struct device *dev, struct scatterlist *sg,
 		return __pci_p2pdma_map_sg(p2p_pgmap, dev, sg, nents);
 		return 0;