Messages in this thread Patch in this message | | | Subject | Re: [PATCH 12/21] dma-iommu: factor atomic pool allocations into helpers | From | Robin Murphy <> | Date | Tue, 9 Apr 2019 18:59:32 +0100 |
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On 27/03/2019 08:04, Christoph Hellwig wrote: > This keeps the code together and will simplify compiling the code > out on architectures that are always dma coherent.
And this is where things take a turn in the direction I just can't get on with - I'm looking at the final result and the twisty maze of little disjoint helpers all overlapping each other in functionality is really difficult to follow. And I would *much* rather have things rely on compile-time constant optimisation than spend the future having to fix the #ifdefed parts for arm64 whenever x86-centric changes fail to test them.
Conceptually, everything except the iommu_dma_alloc_remap() case is more or less just dma_direct_alloc() with an IOMMU mapping on top - if we could pass that an internal flag to say "don't fail or bounce because of masks" it seems like that approach could end up being quite a bit simpler (I did once have lofty plans to refactor the old arm64 code in such a way...)
Robin.
> > Signed-off-by: Christoph Hellwig <hch@lst.de> > --- > drivers/iommu/dma-iommu.c | 51 +++++++++++++++++++++++++++++---------- > 1 file changed, 38 insertions(+), 13 deletions(-) > > diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c > index 2013c650718a..8ec69176673d 100644 > --- a/drivers/iommu/dma-iommu.c > +++ b/drivers/iommu/dma-iommu.c > @@ -673,6 +673,35 @@ static int iommu_dma_get_sgtable_remap(struct sg_table *sgt, void *cpu_addr, > GFP_KERNEL); > } > > +static void iommu_dma_free_pool(struct device *dev, size_t size, > + void *vaddr, dma_addr_t dma_handle) > +{ > + __iommu_dma_unmap(iommu_get_domain_for_dev(dev), dma_handle, size); > + dma_free_from_pool(vaddr, PAGE_ALIGN(size)); > +} > + > +static void *iommu_dma_alloc_pool(struct device *dev, size_t size, > + dma_addr_t *dma_handle, gfp_t gfp, unsigned long attrs) > +{ > + bool coherent = dev_is_dma_coherent(dev); > + struct page *page; > + void *vaddr; > + > + vaddr = dma_alloc_from_pool(PAGE_ALIGN(size), &page, gfp); > + if (!vaddr) > + return NULL; > + > + *dma_handle = __iommu_dma_map(dev, page_to_phys(page), size, > + dma_info_to_prot(DMA_BIDIRECTIONAL, coherent, attrs), > + iommu_get_domain_for_dev(dev)); > + if (*dma_handle == DMA_MAPPING_ERROR) { > + dma_free_from_pool(vaddr, PAGE_ALIGN(size)); > + return NULL; > + } > + > + return vaddr; > +} > + > static void iommu_dma_sync_single_for_cpu(struct device *dev, > dma_addr_t dma_handle, size_t size, enum dma_data_direction dir) > { > @@ -981,21 +1010,18 @@ static void *iommu_dma_alloc(struct device *dev, size_t size, > * get the virtually contiguous buffer we need by way of a > * physically contiguous allocation. > */ > - if (coherent) { > - page = alloc_pages(gfp, get_order(size)); > - addr = page ? page_address(page) : NULL; > - } else { > - addr = dma_alloc_from_pool(size, &page, gfp); > - } > - if (!addr) > + if (!coherent) > + return iommu_dma_alloc_pool(dev, iosize, handle, gfp, > + attrs); > + > + page = alloc_pages(gfp, get_order(size)); > + if (!page) > return NULL; > > + addr = page_address(page); > *handle = __iommu_dma_map_page(dev, page, 0, iosize, ioprot); > if (*handle == DMA_MAPPING_ERROR) { > - if (coherent) > - __free_pages(page, get_order(size)); > - else > - dma_free_from_pool(addr, size); > + __free_pages(page, get_order(size)); > addr = NULL; > } > } else if (attrs & DMA_ATTR_FORCE_CONTIGUOUS) { > @@ -1049,8 +1075,7 @@ static void iommu_dma_free(struct device *dev, size_t size, void *cpu_addr, > * Hence how dodgy the below logic looks... > */ > if (dma_in_atomic_pool(cpu_addr, size)) { > - __iommu_dma_unmap_page(dev, handle, iosize, 0, 0); > - dma_free_from_pool(cpu_addr, size); > + iommu_dma_free_pool(dev, size, cpu_addr, handle); > } else if (attrs & DMA_ATTR_FORCE_CONTIGUOUS) { > struct page *page = vmalloc_to_page(cpu_addr); > >
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