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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181// 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 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)#endifstatic 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;}
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);}
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);}
/** * 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){ if (table->orig_nents <= nents_first_chunk) return;
if (nents_first_chunk == 1) nents_first_chunk = 0;
__sg_free_table(table, SG_CHUNK_SIZE, nents_first_chunk, sg_pool_free, table->orig_nents);}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 * @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){ int ret;
BUG_ON(!nents);
if (first_chunk && nents_first_chunk) { if (nents <= nents_first_chunk) { table->nents = table->orig_nents = nents; sg_init_table(table->sgl, nents); return 0; } }
/* User supposes that the 1st SGL includes real entry */ if (nents_first_chunk <= 1) { first_chunk = NULL; nents_first_chunk = 0; }
ret = __sg_alloc_table(table, nents, SG_CHUNK_SIZE, first_chunk, nents_first_chunk, GFP_ATOMIC, sg_pool_alloc); if (unlikely(ret)) sg_free_table_chained(table, nents_first_chunk); return ret;}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;
mempool_destroy(sgp->pool); kmem_cache_destroy(sgp->slab); }
return -ENOMEM;}
subsys_initcall(sg_pool_init);