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Release 4.18 lib/sg_pool.c

Directory: lib
#include <linux/module.h>
#include <linux/scatterlist.h>
#include <linux/mempool.h>
#include <linux/slab.h>


#define SG_MEMPOOL_NR		ARRAY_SIZE(sg_pools)

#define SG_MEMPOOL_SIZE		2


struct sg_pool {
	
size_t		size;
	
char		*name;
	
struct kmem_cache	*slab;
	
mempool_t	*pool;
};


#define SP(x) { .size = x, "sgpool-" __stringify(x) }
#if (SG_CHUNK_SIZE < 32)
#error SG_CHUNK_SIZE is too small (must be 32 or greater)
#endif

static struct sg_pool sg_pools[] = {
	SP(8),
	SP(16),
#if (SG_CHUNK_SIZE > 32)
	SP(32),
#if (SG_CHUNK_SIZE > 64)
	SP(64),
#if (SG_CHUNK_SIZE > 128)
	SP(128),
#if (SG_CHUNK_SIZE > 256)
#error SG_CHUNK_SIZE is too large (256 MAX)
#endif
#endif
#endif
#endif
	SP(SG_CHUNK_SIZE)
};
#undef SP


static inline unsigned int sg_pool_index(unsigned short nents) { unsigned int index; BUG_ON(nents > SG_CHUNK_SIZE); if (nents <= 8) index = 0; else index = get_count_order(nents) - 3; return index; }

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static void sg_pool_free(struct scatterlist *sgl, unsigned int nents) { struct sg_pool *sgp; sgp = sg_pools + sg_pool_index(nents); mempool_free(sgl, sgp->pool); }

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static struct scatterlist *sg_pool_alloc(unsigned int nents, gfp_t gfp_mask) { struct sg_pool *sgp; sgp = sg_pools + sg_pool_index(nents); return mempool_alloc(sgp->pool, gfp_mask); }

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/** * sg_free_table_chained - Free a previously mapped sg table * @table: The sg table header to use * @first_chunk: was first_chunk not NULL in sg_alloc_table_chained? * * Description: * Free an sg table previously allocated and setup with * sg_alloc_table_chained(). * **/
void sg_free_table_chained(struct sg_table *table, bool first_chunk) { if (first_chunk && table->orig_nents <= SG_CHUNK_SIZE) return; __sg_free_table(table, SG_CHUNK_SIZE, first_chunk, sg_pool_free); }

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EXPORT_SYMBOL_GPL(sg_free_table_chained); /** * 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 * * Description: * Allocate and chain SGLs in an sg table. If @nents@ is larger than * SG_CHUNK_SIZE a chained sg table will be setup. * **/
int sg_alloc_table_chained(struct sg_table *table, int nents, struct scatterlist *first_chunk) { int ret; BUG_ON(!nents); if (first_chunk) { if (nents <= SG_CHUNK_SIZE) { table->nents = table->orig_nents = nents; sg_init_table(table->sgl, nents); return 0; } } ret = __sg_alloc_table(table, nents, SG_CHUNK_SIZE, first_chunk, GFP_ATOMIC, sg_pool_alloc); if (unlikely(ret)) sg_free_table_chained(table, (bool)first_chunk); return ret; }

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EXPORT_SYMBOL_GPL(sg_alloc_table_chained);
static __init int sg_pool_init(void) { int i; for (i = 0; i < SG_MEMPOOL_NR; i++) { struct sg_pool *sgp = sg_pools + i; int size = sgp->size * sizeof(struct scatterlist); sgp->slab = kmem_cache_create(sgp->name, size, 0, SLAB_HWCACHE_ALIGN, NULL); if (!sgp->slab) { printk(KERN_ERR "SG_POOL: can't init sg slab %s\n", sgp->name); goto cleanup_sdb; } sgp->pool = mempool_create_slab_pool(SG_MEMPOOL_SIZE, sgp->slab); if (!sgp->pool) { printk(KERN_ERR "SG_POOL: can't init sg mempool %s\n", sgp->name); goto cleanup_sdb; } } return 0; cleanup_sdb: for (i = 0; i < SG_MEMPOOL_NR; i++) { struct sg_pool *sgp = sg_pools + i; if (sgp->pool) mempool_destroy(sgp->pool); if (sgp->slab) kmem_cache_destroy(sgp->slab); } return -ENOMEM; }

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static __exit void sg_pool_exit(void) { int i; for (i = 0; i < SG_MEMPOOL_NR; i++) { struct sg_pool *sgp = sg_pools + i; mempool_destroy(sgp->pool); kmem_cache_destroy(sgp->slab); } }

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module_init(sg_pool_init); module_exit(sg_pool_exit);

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Directory: lib
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