On Mon, Aug 19, 2019 at 04:29:11PM +0000, Bernard Metzler wrote: > > >To: "Bernard Metzler" <BMT@xxxxxxxxxxxxxx> > >From: "Jason Gunthorpe" <jgg@xxxxxxxx> > >Date: 08/19/2019 06:05PM > >Cc: "Geert Uytterhoeven" <geert@xxxxxxxxxxxxxx>, "Doug Ledford" > ><dledford@xxxxxxxxxx>, linux-rdma@xxxxxxxxxxxxxxx, > >linux-kernel@xxxxxxxxxxxxxxx > >Subject: [EXTERNAL] Re: Re: Re: Re: [PATCH] RDMA/siw: Fix compiler > >warnings on 32-bit due to u64/pointer abuse > > > >On Mon, Aug 19, 2019 at 03:54:56PM +0000, Bernard Metzler wrote: > > > >> Absolutely. But these addresses are conveyed through the > >> API as unsigned 64 during post_send(), and land in the siw > >> send queue as is. During send queue processing, these addresses > >> must be interpreted according to its context and transformed > >> (casted) back to the callers intention. I frankly do not > >> know what we can do differently... The representation of > >> all addresses as unsigned 64 is given. Sorry for the confusion. > > > >send work does not have pointers in it, so I'm confused what this is > >about. Does siw allow userspace to stick an ordinary pointer for the > >SG list? > > Right a user references a buffer by address and local key it > got during reservation of that buffer. The user can provide any > VA between start of that buffer and registered length. Oh gross, it overloads the IOVA in the WR with a kernel void * ?? > >The code paths here must be totally different, so there should be > >different types and functions for each case. > > Yes, there is a function to process application memory (siw_rx_umem), > to process a kernel PBL (siw_rx_pbl), and one to process kernel > addresses (siw_rx_kva). Before running that function, the API > representation of the current SGE gets translated into target > buffer representation. Why does siw_pbl_get_buffer not return a void *?? Still looks like two types have been crammed together. The kernel can't ever store anything into the user WQE buffer, so I would think it would copy the buffer to kernel space, transform it properly and then refer to it as a kernel buffer. Kernel sourced buffers just skip the transofmration. JAson
