Re: [PATCH RFC v1 2/6] swiotlb: convert variables to arrays

[Robin Murphy]

On 2021-02-04 07:29, Christoph Hellwig wrote:
> On Wed, Feb 03, 2021 at 03:37:05PM -0800, Dongli Zhang wrote:
> > This patch converts several swiotlb related variables to arrays, in
> > order to maintain stat/status for different swiotlb buffers. Here are
> > variables involved:
> >
> > - io_tlb_start and io_tlb_end
> > - io_tlb_nslabs and io_tlb_used
> > - io_tlb_list
> > - io_tlb_index
> > - max_segment
> > - io_tlb_orig_addr
> > - no_iotlb_memory
> >
> > There is no functional change and this is to prepare to enable 64-bit
> > swiotlb.
>
> Claire Chang (on Cc) already posted a patch like this a month ago,
> which looks much better because it actually uses a struct instead
> of all the random variables.

Indeed, I skimmed the cover letter and immediately thought that this 
whole thing is just the restricted DMA pool concept[1] again, only from 
a slightly different angle.

Robin.

[1] 
https://lore.kernel.org/linux-iommu/20210106034124.30560-1-tientzu@xxxxxxxxxxxx/