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![Maor Gottlieb](/assets/img/avatar_default.png)
orig_nents should represent the number of entries with pages,
but __sg_alloc_table_from_pages sets orig_nents as the number of
total entries in the table. This is wrong when the API is used for
dynamic allocation where not all the table entries are mapped with
pages. It wasn't observed until now, since RDMA umem who uses this
API in the dynamic form doesn't use orig_nents implicit or explicit
by the scatterlist APIs.
Fix it by changing the append API to track the SG append table
state and have an API to free the append table according to the
total number of entries in the table.
Now all APIs set orig_nents as number of enries with pages.
Fixes: 07da1223ec
("lib/scatterlist: Add support in dynamic allocation of SG table from pages")
Link: https://lore.kernel.org/r/20210824142531.3877007-3-maorg@nvidia.com
Signed-off-by: Maor Gottlieb <maorg@nvidia.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
192 lines
4.2 KiB
C
192 lines
4.2 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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#include <linux/module.h>
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#include <linux/scatterlist.h>
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#include <linux/mempool.h>
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#include <linux/slab.h>
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#define SG_MEMPOOL_NR ARRAY_SIZE(sg_pools)
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#define SG_MEMPOOL_SIZE 2
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struct sg_pool {
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size_t size;
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char *name;
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struct kmem_cache *slab;
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mempool_t *pool;
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};
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#define SP(x) { .size = x, "sgpool-" __stringify(x) }
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#if (SG_CHUNK_SIZE < 32)
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#error SG_CHUNK_SIZE is too small (must be 32 or greater)
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#endif
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static struct sg_pool sg_pools[] = {
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SP(8),
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SP(16),
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#if (SG_CHUNK_SIZE > 32)
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SP(32),
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#if (SG_CHUNK_SIZE > 64)
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SP(64),
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#if (SG_CHUNK_SIZE > 128)
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SP(128),
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#if (SG_CHUNK_SIZE > 256)
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#error SG_CHUNK_SIZE is too large (256 MAX)
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#endif
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#endif
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#endif
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#endif
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SP(SG_CHUNK_SIZE)
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};
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#undef SP
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static inline unsigned int sg_pool_index(unsigned short nents)
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{
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unsigned int index;
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BUG_ON(nents > SG_CHUNK_SIZE);
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if (nents <= 8)
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index = 0;
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else
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index = get_count_order(nents) - 3;
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return index;
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}
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static void sg_pool_free(struct scatterlist *sgl, unsigned int nents)
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{
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struct sg_pool *sgp;
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sgp = sg_pools + sg_pool_index(nents);
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mempool_free(sgl, sgp->pool);
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}
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static struct scatterlist *sg_pool_alloc(unsigned int nents, gfp_t gfp_mask)
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{
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struct sg_pool *sgp;
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sgp = sg_pools + sg_pool_index(nents);
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return mempool_alloc(sgp->pool, gfp_mask);
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}
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/**
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* sg_free_table_chained - Free a previously mapped sg table
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* @table: The sg table header to use
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* @nents_first_chunk: size of the first_chunk SGL passed to
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* sg_alloc_table_chained
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*
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* Description:
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* Free an sg table previously allocated and setup with
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* sg_alloc_table_chained().
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*
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* @nents_first_chunk has to be same with that same parameter passed
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* to sg_alloc_table_chained().
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*
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**/
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void sg_free_table_chained(struct sg_table *table,
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unsigned nents_first_chunk)
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{
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if (table->orig_nents <= nents_first_chunk)
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return;
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if (nents_first_chunk == 1)
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nents_first_chunk = 0;
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__sg_free_table(table, SG_CHUNK_SIZE, nents_first_chunk, sg_pool_free,
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table->orig_nents);
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}
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EXPORT_SYMBOL_GPL(sg_free_table_chained);
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/**
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* sg_alloc_table_chained - Allocate and chain SGLs in an sg table
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* @table: The sg table header to use
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* @nents: Number of entries in sg list
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* @first_chunk: first SGL
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* @nents_first_chunk: number of the SGL of @first_chunk
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*
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* Description:
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* Allocate and chain SGLs in an sg table. If @nents@ is larger than
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* @nents_first_chunk a chained sg table will be setup. @first_chunk is
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* ignored if nents_first_chunk <= 1 because user expects the SGL points
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* non-chain SGL.
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*
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**/
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int sg_alloc_table_chained(struct sg_table *table, int nents,
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struct scatterlist *first_chunk, unsigned nents_first_chunk)
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{
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int ret;
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BUG_ON(!nents);
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if (first_chunk && nents_first_chunk) {
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if (nents <= nents_first_chunk) {
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table->nents = table->orig_nents = nents;
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sg_init_table(table->sgl, nents);
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return 0;
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}
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}
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/* User supposes that the 1st SGL includes real entry */
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if (nents_first_chunk <= 1) {
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first_chunk = NULL;
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nents_first_chunk = 0;
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}
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ret = __sg_alloc_table(table, nents, SG_CHUNK_SIZE,
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first_chunk, nents_first_chunk,
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GFP_ATOMIC, sg_pool_alloc);
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if (unlikely(ret))
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sg_free_table_chained(table, nents_first_chunk);
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return ret;
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}
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EXPORT_SYMBOL_GPL(sg_alloc_table_chained);
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static __init int sg_pool_init(void)
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{
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int i;
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for (i = 0; i < SG_MEMPOOL_NR; i++) {
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struct sg_pool *sgp = sg_pools + i;
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int size = sgp->size * sizeof(struct scatterlist);
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sgp->slab = kmem_cache_create(sgp->name, size, 0,
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SLAB_HWCACHE_ALIGN, NULL);
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if (!sgp->slab) {
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printk(KERN_ERR "SG_POOL: can't init sg slab %s\n",
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sgp->name);
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goto cleanup_sdb;
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}
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sgp->pool = mempool_create_slab_pool(SG_MEMPOOL_SIZE,
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sgp->slab);
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if (!sgp->pool) {
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printk(KERN_ERR "SG_POOL: can't init sg mempool %s\n",
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sgp->name);
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goto cleanup_sdb;
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}
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}
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return 0;
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cleanup_sdb:
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for (i = 0; i < SG_MEMPOOL_NR; i++) {
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struct sg_pool *sgp = sg_pools + i;
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mempool_destroy(sgp->pool);
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kmem_cache_destroy(sgp->slab);
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}
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return -ENOMEM;
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}
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static __exit void sg_pool_exit(void)
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{
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int i;
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for (i = 0; i < SG_MEMPOOL_NR; i++) {
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struct sg_pool *sgp = sg_pools + i;
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mempool_destroy(sgp->pool);
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kmem_cache_destroy(sgp->slab);
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}
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}
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module_init(sg_pool_init);
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module_exit(sg_pool_exit);
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