On Mon, Feb 24, 2020 at 11:44:44AM -0800, Christoph Hellwig wrote: > This allows the arch code to reset the page tables to cached access when > freeing a dma coherent allocation that was set to uncached using > arch_dma_set_uncached. > > Signed-off-by: Christoph Hellwig <hch@xxxxxx> > --- > arch/Kconfig | 7 +++++++ > include/linux/dma-noncoherent.h | 1 + > kernel/dma/direct.c | 2 ++ > 3 files changed, 10 insertions(+) > > diff --git a/arch/Kconfig b/arch/Kconfig > index 090cfe0c82a7..c26302f90c96 100644 > --- a/arch/Kconfig > +++ b/arch/Kconfig > @@ -255,6 +255,13 @@ config ARCH_HAS_SET_DIRECT_MAP > config ARCH_HAS_DMA_SET_UNCACHED > bool > > +# > +# Select if the architectures provides the arch_dma_clear_uncached symbol > +# to undo an in-place page table remap for uncached access. > +# > +config ARCH_HAS_DMA_CLEAR_UNCACHED > + bool > + > # Select if arch init_task must go in the __init_task_data section > config ARCH_TASK_STRUCT_ON_STACK > bool > diff --git a/include/linux/dma-noncoherent.h b/include/linux/dma-noncoherent.h > index 1a4039506673..b59f1b6be3e9 100644 > --- a/include/linux/dma-noncoherent.h > +++ b/include/linux/dma-noncoherent.h > @@ -109,5 +109,6 @@ static inline void arch_dma_prep_coherent(struct page *page, size_t size) > #endif /* CONFIG_ARCH_HAS_DMA_PREP_COHERENT */ > > void *arch_dma_set_uncached(void *addr, size_t size); > +void arch_dma_clear_uncached(void *addr, size_t size); > > #endif /* _LINUX_DMA_NONCOHERENT_H */ > diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c > index f01a8191fd59..a8560052a915 100644 > --- a/kernel/dma/direct.c > +++ b/kernel/dma/direct.c > @@ -219,6 +219,8 @@ void dma_direct_free_pages(struct device *dev, size_t size, void *cpu_addr, > > if (IS_ENABLED(CONFIG_DMA_REMAP) && is_vmalloc_addr(cpu_addr)) > vunmap(cpu_addr); > + else if (IS_ENABLED(CONFIG_ARCH_HAS_DMA_CLEAR_UNCACHED)) > + arch_dma_clear_uncached(cpu_addr, size); Isn't using arch_dma_clear_uncached() before patch 5 going to break bisectability? Ira > > dma_free_contiguous(dev, dma_direct_to_page(dev, dma_addr), size); > } > -- > 2.24.1 >
