Re: [PATCH 0/2] UIO_MEM_DMA_COHERENT for cnic/bnx2/bnx2x

[Greg Kroah-Hartman]

On Wed, Jan 31, 2024 at 11:17:30AM -0800, Chris Leech wrote:
> During bnx2i iSCSI testing we ran into page refcounting issues in the
> uio mmaps exported from cnic to the iscsiuio process, and bisected back
> to the removal of the __GFP_COMP flag from dma_alloc_coherent calls.
> 
> The cnic uio interface also has issues running with an iommu enabled,
> which these changes correct.
> 
> In order to fix these drivers to be able to mmap dma coherent memory via
> a uio device, introduce a new uio mmap type backed by dma_mmap_coherent.
> 
> While I understand some complaints about how these drivers have been
> structured, I also don't like letting support bitrot when there's a
> reasonable alternative to re-architecting an existing driver. I believe
> this to be the most sane way to restore these drivers to functioning
> properly.
> 
> There are two other uio drivers which are mmaping dma_alloc_coherent
> memory as UIO_MEM_PHYS, uio_dmem_genirq and uio_pruss. While a
> conversion to use dma_mmap_coherent might be more correct for these as
> well, I have no way of testing them and assume that this just hasn't
> been an issue for the platforms in question.
> 
> v4:
> - re-introduce the dma_device member to uio_map,
>   it needs to be passed to dma_mmap_coherent somehow
> - drop patch 3 to focus only on the uio interface,
>   explicit page alignment isn't needed
> - re-add the v1 mail recipients,
>   this isn't something to be handled through linux-scsi
> v3 (Nilesh Javali <njavali@xxxxxxxxxxx>):
> - fix warnings reported by kernel test robot
>   and added base commit
> v2 (Nilesh Javali <njavali@xxxxxxxxxxx>):
> - expose only the dma_addr within uio and cnic.
> - Cleanup newly added unions comprising virtual_addr
>   and struct device
> 
> previous threads:
> v1: https://lore.kernel.org/all/20230929170023.1020032-1-cleech@xxxxxxxxxx/
> attempt at an alternative change: https://lore.kernel.org/all/20231219055514.12324-1-njavali@xxxxxxxxxxx/
> v2: https://lore.kernel.org/all/20240103091137.27142-1-njavali@xxxxxxxxxxx/
> v3: https://lore.kernel.org/all/20240109121458.26475-1-njavali@xxxxxxxxxxx/
> 
> Chris Leech (2):
>   uio: introduce UIO_MEM_DMA_COHERENT type
>   cnic,bnx2,bnx2x: use UIO_MEM_DMA_COHERENT
> 
>  drivers/net/ethernet/broadcom/bnx2.c          |  1 +
>  .../net/ethernet/broadcom/bnx2x/bnx2x_main.c  |  2 +
>  drivers/net/ethernet/broadcom/cnic.c          | 15 +++++--
>  drivers/net/ethernet/broadcom/cnic.h          |  1 +
>  drivers/net/ethernet/broadcom/cnic_if.h       |  1 +
>  drivers/uio/uio.c                             | 40 +++++++++++++++++++
>  include/linux/uio_driver.h                    |  3 ++
>  7 files changed, 60 insertions(+), 3 deletions(-)
> 
> 
> base-commit: 861c0981648f5b64c86fd028ee622096eb7af05a
> -- 
> 2.43.0
> 

Hi,

This is the friendly patch-bot of Greg Kroah-Hartman.  You have sent him
a patch that has triggered this response.  He used to manually respond
to these common problems, but in order to save his sanity (he kept
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created.  Hopefully you will not take offence and will fix the problem
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