linux/lib/sg_pool.c
Linus Torvalds 1f7563f743 SCSI sg on 20190709
This topic branch covers a fundamental change in how our sg lists are
 allocated to make mq more efficient by reducing the size of the
 preallocated sg list.  This necessitates a large number of driver
 changes because the previous guarantee that if a driver specified
 SG_ALL as the size of its scatter list, it would get a non-chained
 list and didn't need to bother with scatterlist iterators is now
 broken and every driver *must* use scatterlist iterators.
 
 This was broken out as a separate topic because we need to convert all
 the drivers before pulling the trigger and unconverted drivers kept
 being found, necessitating a rebase.
 
 Signed-off-by: James E.J. Bottomley <jejb@linux.ibm.com>
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Merge tag 'scsi-sg' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi

Pull SCSI scatter-gather list updates from James Bottomley:
 "This topic branch covers a fundamental change in how our sg lists are
  allocated to make mq more efficient by reducing the size of the
  preallocated sg list.

  This necessitates a large number of driver changes because the
  previous guarantee that if a driver specified SG_ALL as the size of
  its scatter list, it would get a non-chained list and didn't need to
  bother with scatterlist iterators is now broken and every driver
  *must* use scatterlist iterators.

  This was broken out as a separate topic because we need to convert all
  the drivers before pulling the trigger and unconverted drivers kept
  being found, necessitating a rebase"

* tag 'scsi-sg' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi: (21 commits)
  scsi: core: don't preallocate small SGL in case of NO_SG_CHAIN
  scsi: lib/sg_pool.c: clear 'first_chunk' in case of no preallocation
  scsi: core: avoid preallocating big SGL for data
  scsi: core: avoid preallocating big SGL for protection information
  scsi: lib/sg_pool.c: improve APIs for allocating sg pool
  scsi: esp: use sg helper to iterate over scatterlist
  scsi: NCR5380: use sg helper to iterate over scatterlist
  scsi: wd33c93: use sg helper to iterate over scatterlist
  scsi: ppa: use sg helper to iterate over scatterlist
  scsi: pcmcia: nsp_cs: use sg helper to iterate over scatterlist
  scsi: imm: use sg helper to iterate over scatterlist
  scsi: aha152x: use sg helper to iterate over scatterlist
  scsi: s390: zfcp_fc: use sg helper to iterate over scatterlist
  scsi: staging: unisys: visorhba: use sg helper to iterate over scatterlist
  scsi: usb: image: microtek: use sg helper to iterate over scatterlist
  scsi: pmcraid: use sg helper to iterate over scatterlist
  scsi: ipr: use sg helper to iterate over scatterlist
  scsi: mvumi: use sg helper to iterate over scatterlist
  scsi: lpfc: use sg helper to iterate over scatterlist
  scsi: advansys: use sg helper to iterate over scatterlist
  ...
2019-07-11 15:17:41 -07:00

192 lines
4.2 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
#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;
}
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);
}
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;
}
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);
}
}
module_init(sg_pool_init);
module_exit(sg_pool_exit);