diff options
| -rw-r--r-- | include/linux/scatterlist.h | 125 | ||||
| -rw-r--r-- | lib/Makefile | 2 | ||||
| -rw-r--r-- | lib/scatterlist.c | 281 |
3 files changed, 307 insertions, 101 deletions
diff --git a/include/linux/scatterlist.h b/include/linux/scatterlist.h index e3ff21d..e9cb103 100644 --- a/include/linux/scatterlist.h +++ b/include/linux/scatterlist.h @@ -7,6 +7,12 @@ #include <linux/string.h> #include <asm/io.h> +struct sg_table { + struct scatterlist *sgl; /* the list */ + unsigned int nents; /* number of mapped entries */ + unsigned int orig_nents; /* original size of list */ +}; + /* * Notes on SG table design. * @@ -106,31 +112,6 @@ static inline void sg_set_buf(struct scatterlist *sg, const void *buf, sg_set_page(sg, virt_to_page(buf), buflen, offset_in_page(buf)); } -/** - * sg_next - return the next scatterlist entry in a list - * @sg: The current sg entry - * - * Description: - * Usually the next entry will be @sg@ + 1, but if this sg element is part - * of a chained scatterlist, it could jump to the start of a new - * scatterlist array. - * - **/ -static inline struct scatterlist *sg_next(struct scatterlist *sg) -{ -#ifdef CONFIG_DEBUG_SG - BUG_ON(sg->sg_magic != SG_MAGIC); -#endif - if (sg_is_last(sg)) - return NULL; - - sg++; - if (unlikely(sg_is_chain(sg))) - sg = sg_chain_ptr(sg); - - return sg; -} - /* * Loop over each sg element, following the pointer to a new list if necessary */ @@ -138,40 +119,6 @@ static inline struct scatterlist *sg_next(struct scatterlist *sg) for (__i = 0, sg = (sglist); __i < (nr); __i++, sg = sg_next(sg)) /** - * sg_last - return the last scatterlist entry in a list - * @sgl: First entry in the scatterlist - * @nents: Number of entries in the scatterlist - * - * Description: - * Should only be used casually, it (currently) scan the entire list - * to get the last entry. - * - * Note that the @sgl@ pointer passed in need not be the first one, - * the important bit is that @nents@ denotes the number of entries that - * exist from @sgl@. - * - **/ -static inline struct scatterlist *sg_last(struct scatterlist *sgl, - unsigned int nents) -{ -#ifndef ARCH_HAS_SG_CHAIN - struct scatterlist *ret = &sgl[nents - 1]; -#else - struct scatterlist *sg, *ret = NULL; - unsigned int i; - - for_each_sg(sgl, sg, nents, i) - ret = sg; - -#endif -#ifdef CONFIG_DEBUG_SG - BUG_ON(sgl[0].sg_magic != SG_MAGIC); - BUG_ON(!sg_is_last(ret)); -#endif - return ret; -} - -/** * sg_chain - Chain two sglists together * @prv: First scatterlist * @prv_nents: Number of entries in prv @@ -223,47 +170,6 @@ static inline void sg_mark_end(struct scatterlist *sg) } /** - * sg_init_table - Initialize SG table - * @sgl: The SG table - * @nents: Number of entries in table - * - * Notes: - * If this is part of a chained sg table, sg_mark_end() should be - * used only on the last table part. - * - **/ -static inline void sg_init_table(struct scatterlist *sgl, unsigned int nents) -{ - memset(sgl, 0, sizeof(*sgl) * nents); -#ifdef CONFIG_DEBUG_SG - { - unsigned int i; - for (i = 0; i < nents; i++) - sgl[i].sg_magic = SG_MAGIC; - } -#endif - sg_mark_end(&sgl[nents - 1]); -} - -/** - * sg_init_one - Initialize a single entry sg list - * @sg: SG entry - * @buf: Virtual address for IO - * @buflen: IO length - * - * Notes: - * This should not be used on a single entry that is part of a larger - * table. Use sg_init_table() for that. - * - **/ -static inline void sg_init_one(struct scatterlist *sg, const void *buf, - unsigned int buflen) -{ - sg_init_table(sg, 1); - sg_set_buf(sg, buf, buflen); -} - -/** * sg_phys - Return physical address of an sg entry * @sg: SG entry * @@ -293,4 +199,23 @@ static inline void *sg_virt(struct scatterlist *sg) return page_address(sg_page(sg)) + sg->offset; } +struct scatterlist *sg_next(struct scatterlist *); +struct scatterlist *sg_last(struct scatterlist *s, unsigned int); +void sg_init_table(struct scatterlist *, unsigned int); +void sg_init_one(struct scatterlist *, const void *, unsigned int); + +typedef struct scatterlist *(sg_alloc_fn)(unsigned int, gfp_t); +typedef void (sg_free_fn)(struct scatterlist *, unsigned int); + +void __sg_free_table(struct sg_table *, sg_free_fn *); +void sg_free_table(struct sg_table *); +int __sg_alloc_table(struct sg_table *, unsigned int, gfp_t, sg_alloc_fn *); +int sg_alloc_table(struct sg_table *, unsigned int, gfp_t); + +/* + * Maximum number of entries that will be allocated in one piece, if + * a list larger than this is required then chaining will be utilized. + */ +#define SG_MAX_SINGLE_ALLOC (PAGE_SIZE / sizeof(struct scatterlist)) + #endif /* _LINUX_SCATTERLIST_H */ diff --git a/lib/Makefile b/lib/Makefile index b6793ed..89841dc 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -6,7 +6,7 @@ lib-y := ctype.o string.o vsprintf.o cmdline.o \ rbtree.o radix-tree.o dump_stack.o \ idr.o int_sqrt.o extable.o prio_tree.o \ sha1.o irq_regs.o reciprocal_div.o argv_split.o \ - proportions.o prio_heap.o + proportions.o prio_heap.o scatterlist.o lib-$(CONFIG_MMU) += ioremap.o lib-$(CONFIG_SMP) += cpumask.o diff --git a/lib/scatterlist.c b/lib/scatterlist.c new file mode 100644 index 0000000..02aaa27 --- /dev/null +++ b/lib/scatterlist.c @@ -0,0 +1,281 @@ +/* + * Copyright (C) 2007 Jens Axboe <jens.axboe@oracle.com> + * + * Scatterlist handling helpers. + * + * This source code is licensed under the GNU General Public License, + * Version 2. See the file COPYING for more details. + */ +#include <linux/module.h> +#include <linux/scatterlist.h> + +/** + * sg_next - return the next scatterlist entry in a list + * @sg: The current sg entry + * + * Description: + * Usually the next entry will be @sg@ + 1, but if this sg element is part + * of a chained scatterlist, it could jump to the start of a new + * scatterlist array. + * + **/ +struct scatterlist *sg_next(struct scatterlist *sg) +{ +#ifdef CONFIG_DEBUG_SG + BUG_ON(sg->sg_magic != SG_MAGIC); +#endif + if (sg_is_last(sg)) + return NULL; + + sg++; + if (unlikely(sg_is_chain(sg))) + sg = sg_chain_ptr(sg); + + return sg; +} +EXPORT_SYMBOL(sg_next); + +/** + * sg_last - return the last scatterlist entry in a list + * @sgl: First entry in the scatterlist + * @nents: Number of entries in the scatterlist + * + * Description: + * Should only be used casually, it (currently) scans the entire list + * to get the last entry. + * + * Note that the @sgl@ pointer passed in need not be the first one, + * the important bit is that @nents@ denotes the number of entries that + * exist from @sgl@. + * + **/ +struct scatterlist *sg_last(struct scatterlist *sgl, unsigned int nents) +{ +#ifndef ARCH_HAS_SG_CHAIN + struct scatterlist *ret = &sgl[nents - 1]; +#else + struct scatterlist *sg, *ret = NULL; + unsigned int i; + + for_each_sg(sgl, sg, nents, i) + ret = sg; + +#endif +#ifdef CONFIG_DEBUG_SG + BUG_ON(sgl[0].sg_magic != SG_MAGIC); + BUG_ON(!sg_is_last(ret)); +#endif + return ret; +} +EXPORT_SYMBOL(sg_last); + +/** + * sg_init_table - Initialize SG table + * @sgl: The SG table + * @nents: Number of entries in table + * + * Notes: + * If this is part of a chained sg table, sg_mark_end() should be + * used only on the last table part. + * + **/ +void sg_init_table(struct scatterlist *sgl, unsigned int nents) +{ + memset(sgl, 0, sizeof(*sgl) * nents); +#ifdef CONFIG_DEBUG_SG + { + unsigned int i; + for (i = 0; i < nents; i++) + sgl[i].sg_magic = SG_MAGIC; + } +#endif + sg_mark_end(&sgl[nents - 1]); +} +EXPORT_SYMBOL(sg_init_table); + +/** + * sg_init_one - Initialize a single entry sg list + * @sg: SG entry + * @buf: Virtual address for IO + * @buflen: IO length + * + **/ +void sg_init_one(struct scatterlist *sg, const void *buf, unsigned int buflen) +{ + sg_init_table(sg, 1); + sg_set_buf(sg, buf, buflen); +} +EXPORT_SYMBOL(sg_init_one); + +/* + * The default behaviour of sg_alloc_table() is to use these kmalloc/kfree + * helpers. + */ +static struct scatterlist *sg_kmalloc(unsigned int nents, gfp_t gfp_mask) +{ + if (nents == SG_MAX_SINGLE_ALLOC) + return (struct scatterlist *) __get_free_page(gfp_mask); + else + return kmalloc(nents * sizeof(struct scatterlist), gfp_mask); +} + +static void sg_kfree(struct scatterlist *sg, unsigned int nents) +{ + if (nents == SG_MAX_SINGLE_ALLOC) + free_page((unsigned long) sg); + else + kfree(sg); +} + +/** + * __sg_free_table - Free a previously mapped sg table + * @table: The sg table header to use + * @free_fn: Free function + * + * Description: + * Free an sg table previously allocated and setup with __sg_alloc_table(). + * + **/ +void __sg_free_table(struct sg_table *table, sg_free_fn *free_fn) +{ + struct scatterlist *sgl, *next; + + if (unlikely(!table->sgl)) + return; + + sgl = table->sgl; + while (table->orig_nents) { + unsigned int alloc_size = table->orig_nents; + unsigned int sg_size; + + /* + * If we have more than SG_MAX_SINGLE_ALLOC segments left, + * then assign 'next' to the sg table after the current one. + * sg_size is then one less than alloc size, since the last + * element is the chain pointer. + */ + if (alloc_size > SG_MAX_SINGLE_ALLOC) { + next = sg_chain_ptr(&sgl[SG_MAX_SINGLE_ALLOC - 1]); + alloc_size = SG_MAX_SINGLE_ALLOC; + sg_size = alloc_size - 1; + } else { + sg_size = alloc_size; + next = NULL; + } + + table->orig_nents -= sg_size; + free_fn(sgl, alloc_size); + sgl = next; + } + + table->sgl = NULL; +} +EXPORT_SYMBOL(__sg_free_table); + +/** + * sg_free_table - Free a previously allocated sg table + * @table: The mapped sg table header + * + **/ +void sg_free_table(struct sg_table *table) +{ + __sg_free_table(table, sg_kfree); +} +EXPORT_SYMBOL(sg_free_table); + +/** + * __sg_alloc_table - Allocate and initialize an sg table with given allocator + * @table: The sg table header to use + * @nents: Number of entries in sg list + * @gfp_mask: GFP allocation mask + * @alloc_fn: Allocator to use + * + * Notes: + * If this function returns non-0 (eg failure), the caller must call + * __sg_free_table() to cleanup any leftover allocations. + * + **/ +int __sg_alloc_table(struct sg_table *table, unsigned int nents, gfp_t gfp_mask, + sg_alloc_fn *alloc_fn) +{ + struct scatterlist *sg, *prv; + unsigned int left; + +#ifndef ARCH_HAS_SG_CHAIN + BUG_ON(nents > SG_MAX_SINGLE_ALLOC); +#endif + + memset(table, 0, sizeof(*table)); + + left = nents; + prv = NULL; + do { + unsigned int sg_size, alloc_size = left; + + if (alloc_size > SG_MAX_SINGLE_ALLOC) { + alloc_size = SG_MAX_SINGLE_ALLOC; + sg_size = alloc_size - 1; + } else + sg_size = alloc_size; + + left -= sg_size; + + sg = alloc_fn(alloc_size, gfp_mask); + if (unlikely(!sg)) + return -ENOMEM; + + sg_init_table(sg, alloc_size); + table->nents = table->orig_nents += sg_size; + + /* + * If this is the first mapping, assign the sg table header. + * If this is not the first mapping, chain previous part. + */ + if (prv) + sg_chain(prv, SG_MAX_SINGLE_ALLOC, sg); + else + table->sgl = sg; + + /* + * If no more entries after this one, mark the end + */ + if (!left) + sg_mark_end(&sg[sg_size - 1]); + + /* + * only really needed for mempool backed sg allocations (like + * SCSI), a possible improvement here would be to pass the + * table pointer into the allocator and let that clear these + * flags + */ + gfp_mask &= ~__GFP_WAIT; + gfp_mask |= __GFP_HIGH; + prv = sg; + } while (left); + + return 0; +} +EXPORT_SYMBOL(__sg_alloc_table); + +/** + * sg_alloc_table - Allocate and initialize an sg table + * @table: The sg table header to use + * @nents: Number of entries in sg list + * @gfp_mask: GFP allocation mask + * + * Description: + * Allocate and initialize an sg table. If @nents@ is larger than + * SG_MAX_SINGLE_ALLOC a chained sg table will be setup. + * + **/ +int sg_alloc_table(struct sg_table *table, unsigned int nents, gfp_t gfp_mask) +{ + int ret; + + ret = __sg_alloc_table(table, nents, gfp_mask, sg_kmalloc); + if (unlikely(ret)) + __sg_free_table(table, sg_kfree); + + return ret; +} +EXPORT_SYMBOL(sg_alloc_table); |