Re: [PATCH v1 01/10] PCI/P2PDMA: Remove redundant bus_offset from map state

Alex Williamson
2025-08-06T20:58:31Z

On Mon, 4 Aug 2025 16:00:36 +0300
Leon Romanovsky <leon@kernel.org> wrote:

> From: Leon Romanovsky <leonro@nvidia.com>
>
> Remove the bus_off field from pci_p2pdma_map_state since it duplicates
> information already available in the pgmap structure. The bus_offset
> is only used in one location (pci_p2pdma_bus_addr_map) and is always
> identical to pgmap->bus_offset.
>
> Reviewed-by: Christoph Hellwig <hch@lst.de>
> Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
> Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
> ---
> drivers/pci/p2pdma.c | 1 -
> include/linux/pci-p2pdma.h | 3 +--
> 2 files changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/drivers/pci/p2pdma.c b/drivers/pci/p2pdma.c
> index da5657a020074..274bb7bcc0bc5 100644
> --- a/drivers/pci/p2pdma.c
> +++ b/drivers/pci/p2pdma.c
> @@ -1009,7 +1009,6 @@ void __pci_p2pdma_update_state(struct pci_p2pdma_map_state *state,
> {
> state->pgmap = page_pgmap(page);
> state->map = pci_p2pdma_map_type(state->pgmap, dev);
> - state->bus_off = to_p2p_pgmap(state->pgmap)->bus_offset;
> }
>
> /**
> diff --git a/include/linux/pci-p2pdma.h b/include/linux/pci-p2pdma.h
> index 075c20b161d98..b502fc8b49bf9 100644
> --- a/include/linux/pci-p2pdma.h
> +++ b/include/linux/pci-p2pdma.h
> @@ -146,7 +146,6 @@ enum pci_p2pdma_map_type {
> struct pci_p2pdma_map_state {
> struct dev_pagemap *pgmap;
> enum pci_p2pdma_map_type map;
> - u64 bus_off;
> };
>
> /* helper for pci_p2pdma_state(), do not use directly */
> @@ -186,7 +185,7 @@ static inline dma_addr_t
> pci_p2pdma_bus_addr_map(struct pci_p2pdma_map_state *state, phys_addr_t paddr)
> {
> WARN_ON_ONCE(state->map != PCI_P2PDMA_MAP_BUS_ADDR);
> - return paddr + state->bus_off;
> + return paddr + to_p2p_pgmap(state->pgmap)->bus_offsetf;
> }
>
> #endif /* _LINUX_PCI_P2P_H */

Looks like you're relying on this bogus code getting resolved in the
next patch...

In file included from kernel/dma/direct.c:16:
./include/linux/pci-p2pdma.h: In function ‘pci_p2pdma_bus_addr_map’:
./include/linux/pci-p2pdma.h:188:24: error: implicit declaration of function ‘to_p2p_pgmap’ [-Wimplicit-function-declaration]
188 | return paddr + to_p2p_pgmap(state->pgmap)->bus_offsetf;
| ^~~~~~~~~~~~
./include/linux/pci-p2pdma.h:188:50: error: invalid type argument of ‘->’ (have ‘int’)
188 | return paddr + to_p2p_pgmap(state->pgmap)->bus_offsetf;
| ^~
./include/linux/pci-p2pdma.h:189:1: error: control reaches end of non-void function [-Werror=return-type]
189 | }
| ^

to_p2p_pgmap() is a static function and struct pci_p2pdma_pagemap
doesn't have a bus_offsetf member. Thanks,

Alex