diff options
Diffstat (limited to 'include/linux/scatterlist.h')
| -rw-r--r-- | include/linux/scatterlist.h | 191 |
1 files changed, 67 insertions, 124 deletions
diff --git a/include/linux/scatterlist.h b/include/linux/scatterlist.h index 457123171389..a3d567a974e8 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. * @@ -26,6 +32,16 @@ #define SG_MAGIC 0x87654321 +/* + * We overload the LSB of the page pointer to indicate whether it's + * a valid sg entry, or whether it points to the start of a new scatterlist. + * Those low bits are there for everyone! (thanks mason :-) + */ +#define sg_is_chain(sg) ((sg)->page_link & 0x01) +#define sg_is_last(sg) ((sg)->page_link & 0x02) +#define sg_chain_ptr(sg) \ + ((struct scatterlist *) ((sg)->page_link & ~0x03)) + /** * sg_assign_page - Assign a given page to an SG entry * @sg: SG entry @@ -47,6 +63,7 @@ static inline void sg_assign_page(struct scatterlist *sg, struct page *page) BUG_ON((unsigned long) page & 0x03); #ifdef CONFIG_DEBUG_SG BUG_ON(sg->sg_magic != SG_MAGIC); + BUG_ON(sg_is_chain(sg)); #endif sg->page_link = page_link | (unsigned long) page; } @@ -73,7 +90,14 @@ static inline void sg_set_page(struct scatterlist *sg, struct page *page, sg->length = len; } -#define sg_page(sg) ((struct page *) ((sg)->page_link & ~0x3)) +static inline struct page *sg_page(struct scatterlist *sg) +{ +#ifdef CONFIG_DEBUG_SG + BUG_ON(sg->sg_magic != SG_MAGIC); + BUG_ON(sg_is_chain(sg)); +#endif + return (struct page *)((sg)->page_link & ~0x3); +} /** * sg_set_buf - Set sg entry to point at given data @@ -89,81 +113,12 @@ static inline void sg_set_buf(struct scatterlist *sg, const void *buf, } /* - * We overload the LSB of the page pointer to indicate whether it's - * a valid sg entry, or whether it points to the start of a new scatterlist. - * Those low bits are there for everyone! (thanks mason :-) - */ -#define sg_is_chain(sg) ((sg)->page_link & 0x01) -#define sg_is_last(sg) ((sg)->page_link & 0x02) -#define sg_chain_ptr(sg) \ - ((struct scatterlist *) ((sg)->page_link & ~0x03)) - -/** - * 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 */ #define for_each_sg(sglist, sg, nr, __i) \ 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; - 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 @@ -179,71 +134,39 @@ static inline void sg_chain(struct scatterlist *prv, unsigned int prv_nents, #ifndef ARCH_HAS_SG_CHAIN BUG(); #endif - prv[prv_nents - 1].page_link = (unsigned long) sgl | 0x01; -} -/** - * sg_mark_end - Mark the end of the scatterlist - * @sgl: Scatterlist - * @nents: Number of entries in sgl - * - * Description: - * Marks the last entry as the termination point for sg_next() - * - **/ -static inline void sg_mark_end(struct scatterlist *sgl, unsigned int nents) -{ - sgl[nents - 1].page_link = 0x02; -} - -static inline void __sg_mark_end(struct scatterlist *sg) -{ - sg->page_link |= 0x02; -} + /* + * offset and length are unused for chain entry. Clear them. + */ + prv[prv_nents - 1].offset = 0; + prv[prv_nents - 1].length = 0; -/** - * 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) -{ - memset(sg, 0, sizeof(*sg)); -#ifdef CONFIG_DEBUG_SG - sg->sg_magic = SG_MAGIC; -#endif - sg_mark_end(sg, 1); - sg_set_buf(sg, buf, buflen); + /* + * Set lowest bit to indicate a link pointer, and make sure to clear + * the termination bit if it happens to be set. + */ + prv[prv_nents - 1].page_link = ((unsigned long) sgl | 0x01) & ~0x02; } /** - * sg_init_table - Initialize SG table - * @sgl: The SG table - * @nents: Number of entries in table + * sg_mark_end - Mark the end of the scatterlist + * @sg: SG entryScatterlist * - * Notes: - * If this is part of a chained sg table, sg_mark_end() should be - * used only on the last table part. + * Description: + * Marks the passed in sg entry as the termination point for the sg + * table. A call to sg_next() on this entry will return NULL. * **/ -static inline void sg_init_table(struct scatterlist *sgl, unsigned int nents) +static inline void sg_mark_end(struct scatterlist *sg) { - memset(sgl, 0, sizeof(*sgl) * nents); - sg_mark_end(sgl, nents); #ifdef CONFIG_DEBUG_SG - { - int i; - for (i = 0; i < nents; i++) - sgl[i].sg_magic = SG_MAGIC; - } + BUG_ON(sg->sg_magic != SG_MAGIC); #endif + /* + * Set termination bit, clear potential chain bit + */ + sg->page_link |= 0x02; + sg->page_link &= ~0x01; } /** @@ -276,4 +199,24 @@ 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 *, unsigned int, sg_free_fn *); +void sg_free_table(struct sg_table *); +int __sg_alloc_table(struct sg_table *, unsigned int, 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 */ |