RE: [PATCH] RDMA/siw: fix pointer cast warning

[Bernard Metzler]

> -----Original Message-----
> From: Arnd Bergmann <arnd@xxxxxxxxxx>
> Sent: Thursday, 15 December 2022 18:04
> To: Bernard Metzler <BMT@xxxxxxxxxxxxxx>; Jason Gunthorpe <jgg@xxxxxxxx>;
> Leon Romanovsky <leon@xxxxxxxxxx>; Linus Walleij <linus.walleij@xxxxxxxxxx>
> Cc: Arnd Bergmann <arnd@xxxxxxxx>; linux-rdma@xxxxxxxxxxxxxxx; linux-
> kernel@xxxxxxxxxxxxxxx
> Subject: [EXTERNAL] [PATCH] RDMA/siw: fix pointer cast warning
> 
> From: Arnd Bergmann <arnd@xxxxxxxx>
> 
> The previous build fix left a remaining issue in configurations
> with 64-bit dma_addr_t on 32-bit architectures:
> 
> drivers/infiniband/sw/siw/siw_qp_tx.c: In function 'siw_get_pblpage':
> drivers/infiniband/sw/siw/siw_qp_tx.c:32:37: error: cast to pointer from
> integer of different size [-Werror=int-to-pointer-cast]
>    32 |                 return virt_to_page((void *)paddr);
>       |                                     ^
> 
> Use the same double cast here that the driver uses elsewhere
> to convert between dma_addr_t and void*.
> 
> It took me a while to figure out why this driver does it
> like this, as there is no hardware access and it just stores
> kernel pointers in place of device addresses when communicating
> with the rdma core and with user space.
> 
> Fixes: 0d1b756acf60 ("RDMA/siw: Pass a pointer to virt_to_page()")
> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
> ---
>  drivers/infiniband/sw/siw/siw_qp_tx.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/infiniband/sw/siw/siw_qp_tx.c
> b/drivers/infiniband/sw/siw/siw_qp_tx.c
> index 7d47b521070b..05052b49107f 100644
> --- a/drivers/infiniband/sw/siw/siw_qp_tx.c
> +++ b/drivers/infiniband/sw/siw/siw_qp_tx.c
> @@ -29,7 +29,7 @@ static struct page *siw_get_pblpage(struct siw_mem *mem,
> u64 addr, int *idx)
>  	dma_addr_t paddr = siw_pbl_get_buffer(pbl, offset, NULL, idx);
> 
>  	if (paddr)
> -		return virt_to_page((void *)paddr);
> +		return virt_to_page((void *)(uintptr_t)paddr);
> 
>  	return NULL;
>  }

Thanks Arnd, makes complete sense.

Acked-by: Bernard Metzler <bmt@xxxxxxxxxxxxxx>