Messages in this thread | | | From | dann frazier <> | Date | Thu, 23 May 2019 19:52:14 -0600 | Subject | Re: [PATCH v2 1/2] dma-contiguous: Abstract dma_{alloc, free}_contiguous() |
| |
On Mon, May 6, 2019 at 4:35 PM Nicolin Chen <nicoleotsuka@gmail.com> wrote: > > Both dma_alloc_from_contiguous() and dma_release_from_contiguous() > are very simply implemented, but requiring callers to pass certain > parameters like count and align, and taking a boolean parameter to > check __GFP_NOWARN in the allocation flags. So every function call > duplicates similar work: > /* A piece of example */ > unsigned long order = get_order(size); > size_t count = size >> PAGE_SHIFT; > page = dma_alloc_from_contiguous(dev, count, order, gfp & __GFP_NOWARN); > [...] > dma_release_from_contiguous(dev, page, size >> PAGE_SHIFT); > > Additionally, as CMA can be used only in the context which permits > sleeping, most of callers do a gfpflags_allow_blocking() check and > a corresponding fallback allocation of normal pages upon any false > result: > /* A piece of example */ > if (gfpflags_allow_blocking(flag)) > page = dma_alloc_from_contiguous(); > if (!page) > page = alloc_pages(); > [...] > if (!dma_release_from_contiguous(dev, page, count)) > __free_pages(page, get_order(size)); > > So this patch simplifies those function calls by abstracting these > operations into the two new functions: dma_{alloc,free}_contiguous. > > As some callers of dma_{alloc,release}_from_contiguous() might be > complicated, this patch just implements these two new functions to > kernel/dma/direct.c only as an initial step. > > Suggested-by: Christoph Hellwig <hch@lst.de> > Signed-off-by: Nicolin Chen <nicoleotsuka@gmail.com> > --- > Changelog > v1->v2: > * Added new functions beside the old ones so we can replace callers > one by one later. > * Applied new functions to dma/direct.c only, because it's the best > example caller to apply and should be safe with the new functions. > > include/linux/dma-contiguous.h | 10 +++++++ > kernel/dma/contiguous.c | 48 ++++++++++++++++++++++++++++++++++ > kernel/dma/direct.c | 24 +++-------------- > 3 files changed, 62 insertions(+), 20 deletions(-) > > diff --git a/include/linux/dma-contiguous.h b/include/linux/dma-contiguous.h > index f247e8aa5e3d..dacbdcb91a89 100644 > --- a/include/linux/dma-contiguous.h > +++ b/include/linux/dma-contiguous.h > @@ -115,6 +115,8 @@ struct page *dma_alloc_from_contiguous(struct device *dev, size_t count, > unsigned int order, bool no_warn); > bool dma_release_from_contiguous(struct device *dev, struct page *pages, > int count); > +struct page *dma_alloc_contiguous(struct device *dev, size_t size, gfp_t gfp); > +void dma_free_contiguous(struct device *dev, struct page *page, size_t size); > > #else > > @@ -157,6 +159,14 @@ bool dma_release_from_contiguous(struct device *dev, struct page *pages, > return false; > } > > +struct page *dma_alloc_contiguous(struct device *dev, size_t size, gfp_t gfp) > +{ > + return NULL; > +} > + > +static inline > +void dma_free_contiguous(struct device *dev, struct page *page, size_t size) { } > + > #endif > > #endif > diff --git a/kernel/dma/contiguous.c b/kernel/dma/contiguous.c > index b2a87905846d..21f39a6cb04f 100644 > --- a/kernel/dma/contiguous.c > +++ b/kernel/dma/contiguous.c > @@ -214,6 +214,54 @@ bool dma_release_from_contiguous(struct device *dev, struct page *pages, > return cma_release(dev_get_cma_area(dev), pages, count); > }
This breaks the build for me if CONFIG_DMA_CMA=n:
LD [M] fs/9p/9p.o ld: fs/9p/vfs_inode.o: in function `dma_alloc_contiguous': vfs_inode.c:(.text+0xa60): multiple definition of `dma_alloc_contiguous'; fs/9p/vfs_super.o:vfs_super.c:(.text+0x500): first defined here
Do the following insertions need to be under an #ifdef CONFIG_DMA_CMA ?
-dann
> +/** > + * dma_alloc_contiguous() - allocate contiguous pages > + * @dev: Pointer to device for which the allocation is performed. > + * @size: Requested allocation size. > + * @gfp: Allocation flags. > + * > + * This function allocates contiguous memory buffer for specified device. It > + * first tries to use device specific contiguous memory area if available or > + * the default global one, then tries a fallback allocation of normal pages. > + */ > +struct page *dma_alloc_contiguous(struct device *dev, size_t size, gfp_t gfp) > +{ > + int node = dev ? dev_to_node(dev) : NUMA_NO_NODE; > + size_t count = PAGE_ALIGN(size) >> PAGE_SHIFT; > + size_t align = get_order(PAGE_ALIGN(size)); > + struct cma *cma = dev_get_cma_area(dev); > + struct page *page = NULL; > + > + /* CMA can be used only in the context which permits sleeping */ > + if (cma && gfpflags_allow_blocking(gfp)) { > + align = min_t(size_t, align, CONFIG_CMA_ALIGNMENT); > + page = cma_alloc(cma, count, align, gfp & __GFP_NOWARN); > + } > + > + /* Fallback allocation of normal pages */ > + if (!page) > + page = alloc_pages_node(node, gfp, align); > + > + return page; > +} > + > +/** > + * dma_free_contiguous() - release allocated pages > + * @dev: Pointer to device for which the pages were allocated. > + * @page: Pointer to the allocated pages. > + * @size: Size of allocated pages. > + * > + * This function releases memory allocated by dma_alloc_contiguous(). As the > + * cma_release returns false when provided pages do not belong to contiguous > + * area and true otherwise, this function then does a fallback __free_pages() > + * upon a false-return. > + */ > +void dma_free_contiguous(struct device *dev, struct page *page, size_t size) > +{ > + if (!cma_release(dev_get_cma_area(dev), page, size >> PAGE_SHIFT)) > + __free_pages(page, get_order(size)); > +} > + > /* > * Support for reserved memory regions defined in device tree > */ > diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c > index 2c2772e9702a..0816c1e8b05a 100644 > --- a/kernel/dma/direct.c > +++ b/kernel/dma/direct.c > @@ -96,8 +96,6 @@ static bool dma_coherent_ok(struct device *dev, phys_addr_t phys, size_t size) > struct page *__dma_direct_alloc_pages(struct device *dev, size_t size, > dma_addr_t *dma_handle, gfp_t gfp, unsigned long attrs) > { > - unsigned int count = PAGE_ALIGN(size) >> PAGE_SHIFT; > - int page_order = get_order(size); > struct page *page = NULL; > u64 phys_mask; > > @@ -109,20 +107,9 @@ struct page *__dma_direct_alloc_pages(struct device *dev, size_t size, > gfp |= __dma_direct_optimal_gfp_mask(dev, dev->coherent_dma_mask, > &phys_mask); > again: > - /* CMA can be used only in the context which permits sleeping */ > - if (gfpflags_allow_blocking(gfp)) { > - page = dma_alloc_from_contiguous(dev, count, page_order, > - gfp & __GFP_NOWARN); > - if (page && !dma_coherent_ok(dev, page_to_phys(page), size)) { > - dma_release_from_contiguous(dev, page, count); > - page = NULL; > - } > - } > - if (!page) > - page = alloc_pages_node(dev_to_node(dev), gfp, page_order); > - > + page = dma_alloc_contiguous(dev, size, gfp); > if (page && !dma_coherent_ok(dev, page_to_phys(page), size)) { > - __free_pages(page, page_order); > + dma_free_contiguous(dev, page, size); > page = NULL; > > if (IS_ENABLED(CONFIG_ZONE_DMA32) && > @@ -154,7 +141,7 @@ void *dma_direct_alloc_pages(struct device *dev, size_t size, > if (PageHighMem(page)) { > /* > * Depending on the cma= arguments and per-arch setup > - * dma_alloc_from_contiguous could return highmem pages. > + * dma_alloc_contiguous could return highmem pages. > * Without remapping there is no way to return them here, > * so log an error and fail. > */ > @@ -176,10 +163,7 @@ void *dma_direct_alloc_pages(struct device *dev, size_t size, > > void __dma_direct_free_pages(struct device *dev, size_t size, struct page *page) > { > - unsigned int count = PAGE_ALIGN(size) >> PAGE_SHIFT; > - > - if (!dma_release_from_contiguous(dev, page, count)) > - __free_pages(page, get_order(size)); > + dma_free_contiguous(dev, page, size); > } > > void dma_direct_free_pages(struct device *dev, size_t size, void *cpu_addr, > -- > 2.17.1 > > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
| |