| Message ID | 20190506223334.1834-2-nicoleotsuka@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Optimize dma_*_from_contiguous calls | expand |
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
On Thu, May 23, 2019 at 7:52 PM dann frazier <dann.frazier@canonical.com> wrote: > > 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 ? Ah, no - the problem is actually a missing "static inline" in the !CONFIG_DMA_CMA version of dma_alloc_contiguous(). -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
On Thu, May 23, 2019 at 08:59:30PM -0600, dann frazier wrote: > > > 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 ? > > Ah, no - the problem is actually a missing "static inline" in the > !CONFIG_DMA_CMA version of dma_alloc_contiguous(). Yea, I saw it. Thanks for the testing and pointing it out. Sending v3.....
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); } +/** + * 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,
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(-)