Re: [PATCH v3 12/20] RDMA/rw: use dma_map_sgtable()

On Thu, Sep 16, 2021 at 05:40:52PM -0600, Logan Gunthorpe wrote:

dma_map_sg() now supports the use of P2PDMA pages so pci_p2pdma_map_sg()
is no longer necessary and may be dropped.

Switch to the dma_map_sgtable() interface which will allow for better
error reporting if the P2PDMA pages are unsupported.

The change to sgtable also appears to fix a couple subtle error path
bugs:

  - In rdma_rw_ctx_init(), dma_unmap would be called with an sg
    that could have been incremented from the original call, as
    well as an nents that was not the original number of nents
    called when mapped.
  - Similarly in rdma_rw_ctx_signature_init, both sg and prot_sg
    were unmapped with the incorrect number of nents.

Those bugs should definately get fixed.. I might extract the sgtable
conversion into a stand alone patch to do it.

But as it is, this looks fine

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>

Jason