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Release 4.12 include/linux/scatterlist.h

Directory: include/linux


#include <linux/string.h>
#include <linux/types.h>
#include <linux/bug.h>
#include <linux/mm.h>
#include <asm/io.h>

struct scatterlist {
unsigned long	sg_magic;
unsigned long	page_link;
unsigned int	offset;
unsigned int	length;
dma_addr_t	dma_address;
unsigned int	dma_length;

 * These macros should be used after a dma_map_sg call has been done
 * to get bus addresses of each of the SG entries and their lengths.
 * You should only work with the number of sg entries dma_map_sg
 * returns, or alternatively stop on the first sg_dma_len(sg) which
 * is 0.

#define sg_dma_address(sg)	((sg)->dma_address)


#define sg_dma_len(sg)		((sg)->dma_length)

#define sg_dma_len(sg)		((sg)->length)

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.
 * We use the unsigned long page_link field in the scatterlist struct to place
 * the page pointer AND encode information about the sg table as well. The two
 * lower bits are reserved for this information.
 * If bit 0 is set, then the page_link contains a pointer to the next sg
 * table list. Otherwise the next entry is at sg + 1.
 * If bit 1 is set, then this sg entry is the last element in a list.
 * See sg_next().

#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
 * @page:           The page
 * Description:
 *   Assign page to sg entry. Also see sg_set_page(), the most commonly used
 *   variant.

static inline void sg_assign_page(struct scatterlist *sg, struct page *page) { unsigned long page_link = sg->page_link & 0x3; /* * In order for the low bit stealing approach to work, pages * must be aligned at a 32-bit boundary as a minimum. */ 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; }


Jens Axboe4865.75%571.43%
Bartlomiej Zolnierkiewicz1723.29%114.29%
Tejun Heo810.96%114.29%

/** * sg_set_page - Set sg entry to point at given page * @sg: SG entry * @page: The page * @len: Length of data * @offset: Offset into page * * Description: * Use this function to set an sg entry pointing at a page, never assign * the page directly. We encode sg table information in the lower bits * of the page pointer. See sg_page() for looking up the page belonging * to an sg entry. * **/
static inline void sg_set_page(struct scatterlist *sg, struct page *page, unsigned int len, unsigned int offset) { sg_assign_page(sg, page); sg->offset = offset; sg->length = len; }


Jens Axboe44100.00%1100.00%

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); }


Tejun Heo4992.45%150.00%
Jens Axboe47.55%150.00%

/** * sg_set_buf - Set sg entry to point at given data * @sg: SG entry * @buf: Data * @buflen: Data length * **/
static inline void sg_set_buf(struct scatterlist *sg, const void *buf, unsigned int buflen) { #ifdef CONFIG_DEBUG_SG BUG_ON(!virt_addr_valid(buf)); #endif sg_set_page(sg, virt_to_page(buf), buflen, offset_in_page(buf)); }


Herbert Xu2751.92%240.00%
Rusty Russell1426.92%120.00%
Jens Axboe1121.15%240.00%

/* * 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_chain - Chain two sglists together * @prv: First scatterlist * @prv_nents: Number of entries in prv * @sgl: Second scatterlist * * Description: * Links @prv@ and @sgl@ together, to form a longer scatterlist. * **/
static inline void sg_chain(struct scatterlist *prv, unsigned int prv_nents, struct scatterlist *sgl) { /* * offset and length are unused for chain entry. Clear them. */ prv[prv_nents - 1].offset = 0; prv[prv_nents - 1].length = 0; /* * 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; }


Jens Axboe4465.67%360.00%
Rusty Russell1217.91%120.00%
Tejun Heo1116.42%120.00%

/** * sg_mark_end - Mark the end of the scatterlist * @sg: SG entryScatterlist * * 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_mark_end(struct scatterlist *sg) { #ifdef CONFIG_DEBUG_SG BUG_ON(sg->sg_magic != SG_MAGIC); #endif /* * Set termination bit, clear potential chain bit */ sg->page_link |= 0x02; sg->page_link &= ~0x01; }


Jens Axboe40100.00%3100.00%

/** * sg_unmark_end - Undo setting the end of the scatterlist * @sg: SG entryScatterlist * * Description: * Removes the termination marker from the given entry of the scatterlist. * **/
static inline void sg_unmark_end(struct scatterlist *sg) { #ifdef CONFIG_DEBUG_SG BUG_ON(sg->sg_magic != SG_MAGIC); #endif sg->page_link &= ~0x02; }


Paolo Bonzini33100.00%1100.00%

/** * sg_phys - Return physical address of an sg entry * @sg: SG entry * * Description: * This calls page_to_phys() on the page in this sg entry, and adds the * sg offset. The caller must know that it is legal to call page_to_phys() * on the sg page. * **/
static inline dma_addr_t sg_phys(struct scatterlist *sg) { return page_to_phys(sg_page(sg)) + sg->offset; }


Jens Axboe2496.00%150.00%
Hugh Dickins14.00%150.00%

/** * sg_virt - Return virtual address of an sg entry * @sg: SG entry * * Description: * This calls page_address() on the page in this sg entry, and adds the * sg offset. The caller must know that the sg page has a valid virtual * mapping. * **/
static inline void *sg_virt(struct scatterlist *sg) { return page_address(sg_page(sg)) + sg->offset; }


Jens Axboe26100.00%1100.00%

int sg_nents(struct scatterlist *sg); int sg_nents_for_len(struct scatterlist *sg, u64 len); 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); int sg_split(struct scatterlist *in, const int in_mapped_nents, const off_t skip, const int nb_splits, const size_t *split_sizes, struct scatterlist **out, int *out_mapped_nents, gfp_t gfp_mask); 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, bool, sg_free_fn *); void sg_free_table(struct sg_table *); int __sg_alloc_table(struct sg_table *, unsigned int, unsigned int, struct scatterlist *, gfp_t, sg_alloc_fn *); int sg_alloc_table(struct sg_table *, unsigned int, gfp_t); int sg_alloc_table_from_pages(struct sg_table *sgt, struct page **pages, unsigned int n_pages, unsigned long offset, unsigned long size, gfp_t gfp_mask); size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents, void *buf, size_t buflen, off_t skip, bool to_buffer); size_t sg_copy_from_buffer(struct scatterlist *sgl, unsigned int nents, const void *buf, size_t buflen); size_t sg_copy_to_buffer(struct scatterlist *sgl, unsigned int nents, void *buf, size_t buflen); size_t sg_pcopy_from_buffer(struct scatterlist *sgl, unsigned int nents, const void *buf, size_t buflen, off_t skip); size_t sg_pcopy_to_buffer(struct scatterlist *sgl, unsigned int nents, void *buf, size_t buflen, off_t skip); /* * 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)) /* * The maximum number of SG segments that we will put inside a * scatterlist (unless chaining is used). Should ideally fit inside a * single page, to avoid a higher order allocation. We could define this * to SG_MAX_SINGLE_ALLOC to pack correctly at the highest order. The * minimum value is 32 */ #define SG_CHUNK_SIZE 128 /* * Like SG_CHUNK_SIZE, but for archs that have sg chaining. This limit * is totally arbitrary, a setting of 2048 will get you at least 8mb ios. */ #ifdef CONFIG_ARCH_HAS_SG_CHAIN #define SG_MAX_SEGMENTS 2048 #else #define SG_MAX_SEGMENTS SG_CHUNK_SIZE #endif #ifdef CONFIG_SG_POOL void sg_free_table_chained(struct sg_table *table, bool first_chunk); int sg_alloc_table_chained(struct sg_table *table, int nents, struct scatterlist *first_chunk); #endif /* * sg page iterator * * Iterates over sg entries page-by-page. On each successful iteration, * you can call sg_page_iter_page(@piter) and sg_page_iter_dma_address(@piter) * to get the current page and its dma address. @piter->sg will point to the * sg holding this page and @piter->sg_pgoffset to the page's page offset * within the sg. The iteration will stop either when a maximum number of sg * entries was reached or a terminating sg (sg_last(sg) == true) was reached. */ struct sg_page_iter { struct scatterlist *sg; /* sg holding the page */ unsigned int sg_pgoffset; /* page offset within the sg */ /* these are internal states, keep away */ unsigned int __nents; /* remaining sg entries */ int __pg_advance; /* nr pages to advance at the * next step */ }; bool __sg_page_iter_next(struct sg_page_iter *piter); void __sg_page_iter_start(struct sg_page_iter *piter, struct scatterlist *sglist, unsigned int nents, unsigned long pgoffset); /** * sg_page_iter_page - get the current page held by the page iterator * @piter: page iterator holding the page */
static inline struct page *sg_page_iter_page(struct sg_page_iter *piter) { return nth_page(sg_page(piter->sg), piter->sg_pgoffset); }


Imre Deak29100.00%1100.00%

/** * sg_page_iter_dma_address - get the dma address of the current page held by * the page iterator. * @piter: page iterator holding the page */
static inline dma_addr_t sg_page_iter_dma_address(struct sg_page_iter *piter) { return sg_dma_address(piter->sg) + (piter->sg_pgoffset << PAGE_SHIFT); }


Imre Deak28100.00%1100.00%

/** * for_each_sg_page - iterate over the pages of the given sg list * @sglist: sglist to iterate over * @piter: page iterator to hold current page, sg, sg_pgoffset * @nents: maximum number of sg entries to iterate over * @pgoffset: starting page offset */ #define for_each_sg_page(sglist, piter, nents, pgoffset) \ for (__sg_page_iter_start((piter), (sglist), (nents), (pgoffset)); \ __sg_page_iter_next(piter);) /* * Mapping sg iterator * * Iterates over sg entries mapping page-by-page. On each successful * iteration, @miter->page points to the mapped page and * @miter->length bytes of data can be accessed at @miter->addr. As * long as an interation is enclosed between start and stop, the user * is free to choose control structure and when to stop. * * @miter->consumed is set to @miter->length on each iteration. It * can be adjusted if the user can't consume all the bytes in one go. * Also, a stopped iteration can be resumed by calling next on it. * This is useful when iteration needs to release all resources and * continue later (e.g. at the next interrupt). */ #define SG_MITER_ATOMIC (1 << 0) /* use kmap_atomic */ #define SG_MITER_TO_SG (1 << 1) /* flush back to phys on unmap */ #define SG_MITER_FROM_SG (1 << 2) /* nop */ struct sg_mapping_iter { /* the following three fields can be accessed directly */ struct page *page; /* currently mapped page */ void *addr; /* pointer to the mapped area */ size_t length; /* length of the mapped area */ size_t consumed; /* number of consumed bytes */ struct sg_page_iter piter; /* page iterator */ /* these are internal states, keep away */ unsigned int __offset; /* offset within page */ unsigned int __remaining; /* remaining bytes on page */ unsigned int __flags; }; void sg_miter_start(struct sg_mapping_iter *miter, struct scatterlist *sgl, unsigned int nents, unsigned int flags); bool sg_miter_skip(struct sg_mapping_iter *miter, off_t offset); bool sg_miter_next(struct sg_mapping_iter *miter); void sg_miter_stop(struct sg_mapping_iter *miter); #endif /* _LINUX_SCATTERLIST_H */

Overall Contributors

Jens Axboe42234.51%1027.03%
Tejun Heo17414.23%25.41%
Imre Deak14011.45%38.11%
Christoph Hellwig776.30%25.41%
Ming Lin554.50%12.70%
Akinobu Mita463.76%12.70%
FUJITA Tomonori403.27%12.70%
Robert Jarzmik393.19%12.70%
Paolo Bonzini342.78%12.70%
Herbert Xu312.53%25.41%
Tomasz Stanislawski302.45%12.70%
Dave Gordon282.29%25.41%
Rusty Russell262.13%25.41%
Bartlomiej Zolnierkiewicz262.13%12.70%
Ming Lei120.98%12.70%
Tom Lendacky120.98%12.70%
Sebastian Andrzej Siewior100.82%12.70%
Maxim Levitsky90.74%12.70%
James Bottomley60.49%12.70%
Hugh Dickins30.25%12.70%
Paul Gortmaker30.25%12.70%
Directory: include/linux
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