Subject: Re: [PATCH v2 00/17] RDMA: Improve use of umem in DMA drivers

From: Jason Gunthorpe <[email-masked]>
Date: Wed, 9 Sep 2020 15:38:48 -0300

On Fri, Sep 04, 2020 at 07:41:41PM -0300, Jason Gunthorpe wrote:
> Most RDMA drivers rely on a linear table of DMA addresses organized in
> some device specific page size.
> 
> For a while now the core code has had the rdma_for_each_block() SG
> iterator to help break a umem into DMA blocks for use in the device lists.
> 
> Improve on this by adding rdma_umem_for_each_dma_block(),
> ib_umem_dma_offset() and ib_umem_num_dma_blocks().
> 
> Replace open codings, or calls to fixed PAGE_SIZE APIs, in most of the
> drivers with one of the above APIs.
> 
> Get rid of the really weird and duplicative ib_umem_page_count().
> 
> Fix two problems with ib_umem_find_best_pgsz(), and several problems
> related to computing the wrong DMA list length if IOVA != umem->address.
> 
> At this point many of the driver have a clear path to call
> ib_umem_find_best_pgsz() and replace hardcoded PAGE_SIZE or PAGE_SHIFT
> values when constructing their DMA lists.
> 
> This is the first series in an effort to modernize the umem usage in all
> the DMA drivers.
> 
> v1: https://lore.kernel.org/r/[email-masked]
> v2:
>  - Fix ib_umem_find_best_pgsz() to use IOVA not umem->addr
>  - Fix ib_umem_num_dma_blocks() to use IOVA not umem->addr
>  - Two new patches to remove wrong open coded versions of
>    ib_umem_num_dma_blocks() from EFA and i40iw
>  - Redo the mlx4 ib_umem_num_dma_blocks() to do less and be safer
>    until the whole thing can be moved to ib_umem_find_best_pgsz()
>  - Two new patches to delete calls to ib_umem_offset() in qedr and
>    ocrdma
> 
> Signed-off-by: Jason Gunthorpe <[email-masked]>
> 
> Jason Gunthorpe (17):
>   RDMA/umem: Fix ib_umem_find_best_pgsz() for mappings that cross a page
>     boundary
>   RDMA/umem: Prevent small pages from being returned by
>     ib_umem_find_best_pgsz()
>   RDMA/umem: Use simpler logic for ib_umem_find_best_pgsz()
>   RDMA/umem: Add rdma_umem_for_each_dma_block()
>   RDMA/umem: Replace for_each_sg_dma_page with
>     rdma_umem_for_each_dma_block
>   RDMA/umem: Split ib_umem_num_pages() into ib_umem_num_dma_blocks()
>   RDMA/efa: Use ib_umem_num_dma_pages()
>   RDMA/i40iw: Use ib_umem_num_dma_pages()
>   RDMA/qedr: Use rdma_umem_for_each_dma_block() instead of open-coding
>   RDMA/qedr: Use ib_umem_num_dma_blocks() instead of
>     ib_umem_page_count()
>   RDMA/bnxt: Do not use ib_umem_page_count() or ib_umem_num_pages()
>   RDMA/hns: Use ib_umem_num_dma_blocks() instead of opencoding
>   RDMA/ocrdma: Use ib_umem_num_dma_blocks() instead of
>     ib_umem_page_count()
>   RDMA/pvrdma: Use ib_umem_num_dma_blocks() instead of
>     ib_umem_page_count()
>   RDMA/mlx4: Use ib_umem_num_dma_blocks()
>   RDMA/qedr: Remove fbo and zbva from the MR
>   RDMA/ocrdma: Remove fbo from MR

Applied to for-next with Leon's note. Thanks everyone

Jason