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author | Bart Van Assche <bart.vanassche@wdc.com> | 2018-01-05 08:26:46 -0800 |
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committer | Jens Axboe <axboe@kernel.dk> | 2018-01-06 09:18:00 -0700 |
commit | e80a0af4759a164214f02da157a3800753ce135f (patch) | |
tree | efd4cbbac280618e1cd6e9dd464730a739c2b37f /lib | |
parent | bbbc3c1cfaf6900d24e3c9fcaac25d267ad2bc40 (diff) | |
download | op-kernel-dev-e80a0af4759a164214f02da157a3800753ce135f.zip op-kernel-dev-e80a0af4759a164214f02da157a3800753ce135f.tar.gz |
lib/scatterlist: Introduce sgl_alloc() and sgl_free()
Many kernel drivers contain code that allocates and frees both a
scatterlist and the pages that populate that scatterlist.
Introduce functions in lib/scatterlist.c that perform these tasks
instead of duplicating this functionality in multiple drivers.
Only include these functions in the build if CONFIG_SGL_ALLOC=y
to avoid that the kernel size increases if this functionality is
not used.
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'lib')
-rw-r--r-- | lib/Kconfig | 4 | ||||
-rw-r--r-- | lib/scatterlist.c | 105 |
2 files changed, 109 insertions, 0 deletions
diff --git a/lib/Kconfig b/lib/Kconfig index c5e84fb..4dd5c11 100644 --- a/lib/Kconfig +++ b/lib/Kconfig @@ -409,6 +409,10 @@ 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/scatterlist.c b/lib/scatterlist.c index 7c1c55f..9afc9b4 100644 --- a/lib/scatterlist.c +++ b/lib/scatterlist.c @@ -474,6 +474,111 @@ int sg_alloc_table_from_pages(struct sg_table *sgt, struct page **pages, } EXPORT_SYMBOL(sg_alloc_table_from_pages); +#ifdef CONFIG_SGL_ALLOC + +/** + * 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() + * @chainable: Whether or not to allocate an extra element in the scatterlist + * for scatterlist chaining purposes + * @gfp: Memory allocation flags + * @nent_p: [out] Number of entries in the scatterlist that have pages + * + * Returns: A pointer to an initialized scatterlist or %NULL upon failure. + */ +struct scatterlist *sgl_alloc_order(unsigned long long length, + unsigned int order, bool chainable, + gfp_t gfp, unsigned int *nent_p) +{ + struct scatterlist *sgl, *sg; + struct page *page; + unsigned int nent, nalloc; + u32 elem_len; + + nent = round_up(length, PAGE_SIZE << order) >> (PAGE_SHIFT + order); + /* Check for integer overflow */ + if (length > (nent << (PAGE_SHIFT + order))) + return NULL; + 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 + * @gfp: Memory allocation flags + * @nent_p: [out] Number of entries in the scatterlist + * + * Returns: A pointer to an initialized scatterlist or %NULL upon failure. + */ +struct scatterlist *sgl_alloc(unsigned long long length, gfp_t gfp, + unsigned int *nent_p) +{ + return sgl_alloc_order(length, 0, false, gfp, nent_p); +} +EXPORT_SYMBOL(sgl_alloc); + +/** + * sgl_free_order - free a scatterlist and its pages + * @sgl: 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 + * @sgl: Scatterlist with one or more elements + */ +void sgl_free(struct scatterlist *sgl) +{ + sgl_free_order(sgl, 0); +} +EXPORT_SYMBOL(sgl_free); + +#endif /* CONFIG_SGL_ALLOC */ + void __sg_page_iter_start(struct sg_page_iter *piter, struct scatterlist *sglist, unsigned int nents, unsigned long pgoffset) |