linux/lib/sg_pool.c

// SPDX-License-Identifier: GPL-2.0-only
#include <linux/init.h>
#include <linux/scatterlist.h>
#include <linux/mempool.h>
#include <linux/slab.h>

#define SG_MEMPOOL_NR …
#define SG_MEMPOOL_SIZE …

struct sg_pool { … };

#define SP …
#if (SG_CHUNK_SIZE < 32)
#error SG_CHUNK_SIZE is too small (must be 32 or greater)
#endif
static struct sg_pool sg_pools[] = …;
#undef SP

static inline unsigned int sg_pool_index(unsigned short nents)
{ … }

static void sg_pool_free(struct scatterlist *sgl, unsigned int nents)
{ … }

static struct scatterlist *sg_pool_alloc(unsigned int nents, gfp_t gfp_mask)
{ … }

/**
 * sg_free_table_chained - Free a previously mapped sg table
 * @table:	The sg table header to use
 * @nents_first_chunk: size of the first_chunk SGL passed to
 *		sg_alloc_table_chained
 *
 *  Description:
 *    Free an sg table previously allocated and setup with
 *    sg_alloc_table_chained().
 *
 *    @nents_first_chunk has to be same with that same parameter passed
 *    to sg_alloc_table_chained().
 *
 **/
void sg_free_table_chained(struct sg_table *table,
		unsigned nents_first_chunk)
{ … }
EXPORT_SYMBOL_GPL(…);

/**
 * sg_alloc_table_chained - Allocate and chain SGLs in an sg table
 * @table:	The sg table header to use
 * @nents:	Number of entries in sg list
 * @first_chunk: first SGL
 * @nents_first_chunk: number of the SGL of @first_chunk
 *
 *  Description:
 *    Allocate and chain SGLs in an sg table. If @nents@ is larger than
 *    @nents_first_chunk a chained sg table will be setup. @first_chunk is
 *    ignored if nents_first_chunk <= 1 because user expects the SGL points
 *    non-chain SGL.
 *
 **/
int sg_alloc_table_chained(struct sg_table *table, int nents,
		struct scatterlist *first_chunk, unsigned nents_first_chunk)
{ … }
EXPORT_SYMBOL_GPL(…);

static __init int sg_pool_init(void)
{ … }

subsys_initcall(sg_pool_init);