Re: Re: [PATCH next] siw: Fix pointer-to-int-cast warning in siw_rx_pbl()

[Jason Gunthorpe <jgg@ziepe.ca>]

On Thu, Jun 11, 2020 at 10:21:49AM +0000, Bernard Metzler wrote:
> 
> >To: "Tom Seewald" <tseewald@gmail.com>
> >From: "Jason Gunthorpe" <jgg@ziepe.ca>
> >Date: 06/10/2020 07:50PM
> >Cc: linux-rdma@vger.kernel.org, "Bernard Metzler"
> ><bmt@zurich.ibm.com>, "Doug Ledford" <dledford@redhat.com>
> >Subject: [EXTERNAL] Re: [PATCH next] siw: Fix pointer-to-int-cast
> >warning in siw_rx_pbl()
> >
> >On Wed, Jun 10, 2020 at 12:47:17PM -0500, Tom Seewald wrote:
> >> The variable buf_addr is type dma_addr_t, which may not be the same
> >size
> >> as a pointer.  To ensure it is the correct size, cast to a
> >uintptr_t.
> >> 
> >> Signed-off-by: Tom Seewald <tseewald@gmail.com>
> >>  drivers/infiniband/sw/siw/siw_qp_rx.c | 3 ++-
> >>  1 file changed, 2 insertions(+), 1 deletion(-)
> >> 
> >> diff --git a/drivers/infiniband/sw/siw/siw_qp_rx.c
> >b/drivers/infiniband/sw/siw/siw_qp_rx.c
> >> index 650520244ed0..7271d705f4b0 100644
> >> +++ b/drivers/infiniband/sw/siw/siw_qp_rx.c
> >> @@ -139,7 +139,8 @@ static int siw_rx_pbl(struct siw_rx_stream
> >*srx, int *pbl_idx,
> >>  			break;
> >>  
> >>  		bytes = min(bytes, len);
> >> -		if (siw_rx_kva(srx, (void *)buf_addr, bytes) == bytes) {
> >> +		if (siw_rx_kva(srx, (void *)(uintptr_t)buf_addr, bytes) ==
> >> +		    bytes) {
> >
> >How is a dma_addr_t being cast to a void *? That can't be right?
> >Bernard??
> >
> >Jason
> >
> Hi Tom, Hi Jason,
> 
> Thanks for looking into that.
> 
> siw_rx_kva() calls skb_copy_bits() to move data to its
> kernel clients destination.  It expects a void * target
> address. This is why I chose it for siw_rx_kva() as well.
> One could say siw_rx_kva() should better get an uintptr_t
> as target argument, which would probably make it look
> more clean. And we rename it to siw_rx_kbuf(), and we
> cast from uintptr_t to (void *) just for
>  skb_copy_bits(skb *, off, (void *)dest, len)
> 
> This would avoid all those nasty (void *) casting at all (!)
> the places we are calling siw_rx_kva().

But where did the dma_addr_t come from?

Jason