linux-stable/lib/sg_pool.c
Masahiro Yamada f7f04d1983 lib/sg_pool: change module_init(sg_pool_init) to subsys_initcall
sg_alloc_table_chained() is called by several drivers, but if it is
called before sg_pool_init(), it results in a NULL pointer dereference
in sg_pool_alloc().

Since commit 9b1d6c8950 ("lib: scatterlist: move SG pool code from
SCSI driver to lib/sg_pool.c"), we rely on module_init(sg_pool_init)
is invoked before other module_init calls but this assumption is
fragile.

I slightly changed the link order while refactoring Kbuild, then
uncovered this issue. I should keep the current link order, but
depending on a specific call order among module_init is so fragile.

We usually define the init order by specifying *_initcall correctly,
or delay the driver probing by returning -EPROBE_DEFER.

Change module_initcall() to subsys_initcall(), and also delete the
pointless module_exit() because lib/sg_pool.c is always compiled as
built-in. (CONFIG_SG_POOL is bool)

Link: https://lore.kernel.org/all/20220921043946.GA1355561@roeck-us.net/
Link: https://lore.kernel.org/all/8e70837d-d859-dfb2-bf7f-83f8b31467bc@samsung.com/
Fixes: 9b1d6c8950 ("lib: scatterlist: move SG pool code from SCSI driver to lib/sg_pool.c")
Reported-by: Guenter Roeck <linux@roeck-us.net>
Reported-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
2022-09-23 16:46:19 +02:00

180 lines
4 KiB
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 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,
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);