Re: [PATCH v3] RDMA/siw: Pass a pointer to virt_to_page()

From: Leon Romanovsky <leonro@nvidia.com>
To: Linus Walleij <linus.walleij@linaro.org>
Cc: Jason Gunthorpe <jgg@nvidia.com>,
	Bernard Metzler <BMT@zurich.ibm.com>,
	<linux-rdma@vger.kernel.org>
Subject: Re: [PATCH v3] RDMA/siw: Pass a pointer to virt_to_page()
Date: Sun, 4 Sep 2022 10:22:44 +0300	[thread overview]
Message-ID: <YxRSRIOs3gEEAyGN@unreal> (raw)
In-Reply-To: <20220902215918.603761-1-linus.walleij@linaro.org>

On Fri, Sep 02, 2022 at 11:59:18PM +0200, Linus Walleij wrote:
> Functions that work on a pointer to virtual memory such as
> virt_to_pfn() and users of that function such as
> virt_to_page() are supposed to pass a pointer to virtual
> memory, ideally a (void *) or other pointer. However since
> many architectures implement virt_to_pfn() as a macro,
> this function becomes polymorphic and accepts both a
> (unsigned long) and a (void *).
> 
> If we instead implement a proper virt_to_pfn(void *addr)
> function the following happens (occurred on arch/arm):
> 
> drivers/infiniband/sw/siw/siw_qp_tx.c:32:23: warning: incompatible
>   integer to pointer conversion passing 'dma_addr_t' (aka 'unsigned int')
>   to parameter of type 'const void *' [-Wint-conversion]
> drivers/infiniband/sw/siw/siw_qp_tx.c:32:37: warning: passing argument
>   1 of 'virt_to_pfn' makes pointer from integer without a cast
>   [-Wint-conversion]
> drivers/infiniband/sw/siw/siw_qp_tx.c:538:36: warning: incompatible
>   integer to pointer conversion passing 'unsigned long long'
>   to parameter of type 'const void *' [-Wint-conversion]
> 
> Fix this with an explicit cast. In one case where the SIW
> SGE uses an unaligned u64 we need a double cast modifying the
> virtual address (va) to a platform-specific uintptr_t before
> casting to a (void *).
> 
> Fixes: b9be6f18cf9e ("rdma/siw: transmit path")
> Cc: linux-rdma@vger.kernel.org
> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
> ---
> ChangeLog v2->v3:
> - Add Fixes: tag.
> ChangeLog v1->v2:
> - Change the local va variable to be uintptr_t, avoiding
>   double casts in two spots.
> ---
>  drivers/infiniband/sw/siw/siw_qp_tx.c | 18 ++++++++++++++----
>  1 file changed, 14 insertions(+), 4 deletions(-)
> 

Thanks, applied.