Many kernel drivers contain code that allocate and free both a scatterlist and the pages that populate that scatterlist. Introduce functions under lib/ that perform these tasks instead of duplicating this functionality in multiple drivers.
Signed-off-by: Bart Van Assche <[email protected]> --- include/linux/sgl_alloc.h | 16 ++++++++ lib/Kconfig | 4 ++ lib/Makefile | 1 + lib/sgl_alloc.c | 102 ++++++++++++++++++++++++++++++++++++++++++++++ 4 files changed, 123 insertions(+) create mode 100644 include/linux/sgl_alloc.h create mode 100644 lib/sgl_alloc.c diff --git a/include/linux/sgl_alloc.h b/include/linux/sgl_alloc.h new file mode 100644 index 000000000000..a0f719690c9e --- /dev/null +++ b/include/linux/sgl_alloc.h @@ -0,0 +1,16 @@ +#ifndef _SGL_ALLOC_H_ +#define _SGL_ALLOC_H_ + +#include <linux/types.h> /* bool, gfp_t */ + +struct scatterlist; + +struct scatterlist *sgl_alloc_order(unsigned long long length, + unsigned int order, unsigned int *nent_p, + gfp_t gfp, bool chainable); +struct scatterlist *sgl_alloc(unsigned long long length, unsigned int *nent_p, + gfp_t gfp); +void sgl_free_order(struct scatterlist *sgl, int order); +void sgl_free(struct scatterlist *sgl); + +#endif /* _SGL_ALLOC_H_ */ diff --git a/lib/Kconfig b/lib/Kconfig index b1445b22a6de..8396c4cfa1ab 100644 --- a/lib/Kconfig +++ b/lib/Kconfig @@ -413,6 +413,10 @@ config HAS_DMA depends on !NO_DMA default y +config SGL_ALLOC + bool + default n + config DMA_NOOP_OPS bool depends on HAS_DMA && (!64BIT || ARCH_DMA_ADDR_T_64BIT) diff --git a/lib/Makefile b/lib/Makefile index dafa79613fb4..4a0e9caf3c0e 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -27,6 +27,7 @@ lib-y := ctype.o string.o vsprintf.o cmdline.o \ lib-$(CONFIG_MMU) += ioremap.o lib-$(CONFIG_SMP) += cpumask.o +lib-$(CONFIG_SGL_ALLOC) += sgl_alloc.o lib-$(CONFIG_DMA_NOOP_OPS) += dma-noop.o lib-$(CONFIG_DMA_VIRT_OPS) += dma-virt.o diff --git a/lib/sgl_alloc.c b/lib/sgl_alloc.c new file mode 100644 index 000000000000..d96b395dd5c8 --- /dev/null +++ b/lib/sgl_alloc.c @@ -0,0 +1,102 @@ +#include <linux/kernel.h> +#include <linux/scatterlist.h> +#include <linux/sgl_alloc.h> +#include <linux/slab.h> +#include <linux/types.h> +#include <asm/page.h> + +/** + * sgl_alloc_order - allocate a scatterlist and its pages + * @length: Length in bytes of the scatterlist. Must be at least one + * @order: Second argument for alloc_pages() + * @nent_p: [out] Number of entries in the scatterlist that have pages + * @gfp: Memory allocation flags + * @chainable: Whether or not to allocate an extra element in the scatterlist + * for scatterlist chaining purposes + * + * Returns: %NULL upon failure or a pointer to an initialized scatterlist. + */ +struct scatterlist *sgl_alloc_order(unsigned long long length, + unsigned int order, unsigned int *nent_p, + gfp_t gfp, bool chainable) +{ + struct scatterlist *sgl, *sg; + struct page *page; + unsigned int nent, nalloc; + u32 elem_len; + + nent = round_up(length, PAGE_SIZE << order) >> (PAGE_SHIFT + order); + nalloc = nent; + if (chainable) { + /* Check for integer overflow */ + if (nalloc + 1 < nalloc) + return NULL; + nalloc++; + } + sgl = kmalloc_array(nalloc, sizeof(struct scatterlist), + (gfp & ~GFP_DMA) | __GFP_ZERO); + if (!sgl) + return NULL; + + sg_init_table(sgl, nent); + sg = sgl; + while (length) { + elem_len = min_t(u64, length, PAGE_SIZE << order); + page = alloc_pages(gfp, order); + if (!page) { + sgl_free(sgl); + return NULL; + } + + sg_set_page(sg, page, elem_len, 0); + length -= elem_len; + sg = sg_next(sg); + } + WARN_ON_ONCE(sg); + if (nent_p) + *nent_p = nent; + return sgl; +} +EXPORT_SYMBOL(sgl_alloc_order); + +/** + * sgl_alloc - allocate a scatterlist and its pages + * @length: Length in bytes of the scatterlist + * @nent_p: [out] Number of entries in the scatterlist + * @gfp: Memory allocation flags + */ +struct scatterlist *sgl_alloc(unsigned long long length, unsigned int *nent_p, + gfp_t gfp) +{ + return sgl_alloc_order(length, 0, nent_p, gfp, false); +} +EXPORT_SYMBOL(sgl_alloc); + +/** + * sgl_free_order - free a scatterlist and its pages + * @sg: Scatterlist with one or more elements + * @order: Second argument for __free_pages() + */ +void sgl_free_order(struct scatterlist *sgl, int order) +{ + struct scatterlist *sg; + struct page *page; + + for (sg = sgl; sg; sg = sg_next(sg)) { + page = sg_page(sg); + if (page) + __free_pages(page, order); + } + kfree(sgl); +} +EXPORT_SYMBOL(sgl_free_order); + +/** + * sgl_free - free a scatterlist and its pages + * @sg: Scatterlist with one or more elements + */ +void sgl_free(struct scatterlist *sgl) +{ + sgl_free_order(sgl, 0); +} +EXPORT_SYMBOL(sgl_free); -- 2.14.2
