mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-27 19:29:37 +00:00
![Gustavo A. R. Silva](/assets/img/avatar_default.png)
The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:
struct foo {
int stuff;
struct boo array[];
};
By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.
Also, notice that, dynamic memory allocations won't be affected by
this change:
"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]
This issue was found with the help of Coccinelle.
[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 7649773293
("cxgb3/l2t: Fix undefined behaviour")
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
222 lines
7.7 KiB
C
222 lines
7.7 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
|
|
/*
|
|
* Basic general purpose allocator for managing special purpose
|
|
* memory, for example, memory that is not managed by the regular
|
|
* kmalloc/kfree interface. Uses for this includes on-device special
|
|
* memory, uncached memory etc.
|
|
*
|
|
* It is safe to use the allocator in NMI handlers and other special
|
|
* unblockable contexts that could otherwise deadlock on locks. This
|
|
* is implemented by using atomic operations and retries on any
|
|
* conflicts. The disadvantage is that there may be livelocks in
|
|
* extreme cases. For better scalability, one allocator can be used
|
|
* for each CPU.
|
|
*
|
|
* The lockless operation only works if there is enough memory
|
|
* available. If new memory is added to the pool a lock has to be
|
|
* still taken. So any user relying on locklessness has to ensure
|
|
* that sufficient memory is preallocated.
|
|
*
|
|
* The basic atomic operation of this allocator is cmpxchg on long.
|
|
* On architectures that don't have NMI-safe cmpxchg implementation,
|
|
* the allocator can NOT be used in NMI handler. So code uses the
|
|
* allocator in NMI handler should depend on
|
|
* CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG.
|
|
*/
|
|
|
|
|
|
#ifndef __GENALLOC_H__
|
|
#define __GENALLOC_H__
|
|
|
|
#include <linux/types.h>
|
|
#include <linux/spinlock_types.h>
|
|
#include <linux/atomic.h>
|
|
|
|
struct device;
|
|
struct device_node;
|
|
struct gen_pool;
|
|
|
|
/**
|
|
* typedef genpool_algo_t: Allocation callback function type definition
|
|
* @map: Pointer to bitmap
|
|
* @size: The bitmap size in bits
|
|
* @start: The bitnumber to start searching at
|
|
* @nr: The number of zeroed bits we're looking for
|
|
* @data: optional additional data used by the callback
|
|
* @pool: the pool being allocated from
|
|
*/
|
|
typedef unsigned long (*genpool_algo_t)(unsigned long *map,
|
|
unsigned long size,
|
|
unsigned long start,
|
|
unsigned int nr,
|
|
void *data, struct gen_pool *pool,
|
|
unsigned long start_addr);
|
|
|
|
/*
|
|
* General purpose special memory pool descriptor.
|
|
*/
|
|
struct gen_pool {
|
|
spinlock_t lock;
|
|
struct list_head chunks; /* list of chunks in this pool */
|
|
int min_alloc_order; /* minimum allocation order */
|
|
|
|
genpool_algo_t algo; /* allocation function */
|
|
void *data;
|
|
|
|
const char *name;
|
|
};
|
|
|
|
/*
|
|
* General purpose special memory pool chunk descriptor.
|
|
*/
|
|
struct gen_pool_chunk {
|
|
struct list_head next_chunk; /* next chunk in pool */
|
|
atomic_long_t avail;
|
|
phys_addr_t phys_addr; /* physical starting address of memory chunk */
|
|
void *owner; /* private data to retrieve at alloc time */
|
|
unsigned long start_addr; /* start address of memory chunk */
|
|
unsigned long end_addr; /* end address of memory chunk (inclusive) */
|
|
unsigned long bits[]; /* bitmap for allocating memory chunk */
|
|
};
|
|
|
|
/*
|
|
* gen_pool data descriptor for gen_pool_first_fit_align.
|
|
*/
|
|
struct genpool_data_align {
|
|
int align; /* alignment by bytes for starting address */
|
|
};
|
|
|
|
/*
|
|
* gen_pool data descriptor for gen_pool_fixed_alloc.
|
|
*/
|
|
struct genpool_data_fixed {
|
|
unsigned long offset; /* The offset of the specific region */
|
|
};
|
|
|
|
extern struct gen_pool *gen_pool_create(int, int);
|
|
extern phys_addr_t gen_pool_virt_to_phys(struct gen_pool *pool, unsigned long);
|
|
extern int gen_pool_add_owner(struct gen_pool *, unsigned long, phys_addr_t,
|
|
size_t, int, void *);
|
|
|
|
static inline int gen_pool_add_virt(struct gen_pool *pool, unsigned long addr,
|
|
phys_addr_t phys, size_t size, int nid)
|
|
{
|
|
return gen_pool_add_owner(pool, addr, phys, size, nid, NULL);
|
|
}
|
|
|
|
/**
|
|
* gen_pool_add - add a new chunk of special memory to the pool
|
|
* @pool: pool to add new memory chunk to
|
|
* @addr: starting address of memory chunk to add to pool
|
|
* @size: size in bytes of the memory chunk to add to pool
|
|
* @nid: node id of the node the chunk structure and bitmap should be
|
|
* allocated on, or -1
|
|
*
|
|
* Add a new chunk of special memory to the specified pool.
|
|
*
|
|
* Returns 0 on success or a -ve errno on failure.
|
|
*/
|
|
static inline int gen_pool_add(struct gen_pool *pool, unsigned long addr,
|
|
size_t size, int nid)
|
|
{
|
|
return gen_pool_add_virt(pool, addr, -1, size, nid);
|
|
}
|
|
extern void gen_pool_destroy(struct gen_pool *);
|
|
unsigned long gen_pool_alloc_algo_owner(struct gen_pool *pool, size_t size,
|
|
genpool_algo_t algo, void *data, void **owner);
|
|
|
|
static inline unsigned long gen_pool_alloc_owner(struct gen_pool *pool,
|
|
size_t size, void **owner)
|
|
{
|
|
return gen_pool_alloc_algo_owner(pool, size, pool->algo, pool->data,
|
|
owner);
|
|
}
|
|
|
|
static inline unsigned long gen_pool_alloc_algo(struct gen_pool *pool,
|
|
size_t size, genpool_algo_t algo, void *data)
|
|
{
|
|
return gen_pool_alloc_algo_owner(pool, size, algo, data, NULL);
|
|
}
|
|
|
|
/**
|
|
* gen_pool_alloc - allocate special memory from the pool
|
|
* @pool: pool to allocate from
|
|
* @size: number of bytes to allocate from the pool
|
|
*
|
|
* Allocate the requested number of bytes from the specified pool.
|
|
* Uses the pool allocation function (with first-fit algorithm by default).
|
|
* Can not be used in NMI handler on architectures without
|
|
* NMI-safe cmpxchg implementation.
|
|
*/
|
|
static inline unsigned long gen_pool_alloc(struct gen_pool *pool, size_t size)
|
|
{
|
|
return gen_pool_alloc_algo(pool, size, pool->algo, pool->data);
|
|
}
|
|
|
|
extern void *gen_pool_dma_alloc(struct gen_pool *pool, size_t size,
|
|
dma_addr_t *dma);
|
|
extern void *gen_pool_dma_alloc_algo(struct gen_pool *pool, size_t size,
|
|
dma_addr_t *dma, genpool_algo_t algo, void *data);
|
|
extern void *gen_pool_dma_alloc_align(struct gen_pool *pool, size_t size,
|
|
dma_addr_t *dma, int align);
|
|
extern void *gen_pool_dma_zalloc(struct gen_pool *pool, size_t size, dma_addr_t *dma);
|
|
extern void *gen_pool_dma_zalloc_algo(struct gen_pool *pool, size_t size,
|
|
dma_addr_t *dma, genpool_algo_t algo, void *data);
|
|
extern void *gen_pool_dma_zalloc_align(struct gen_pool *pool, size_t size,
|
|
dma_addr_t *dma, int align);
|
|
extern void gen_pool_free_owner(struct gen_pool *pool, unsigned long addr,
|
|
size_t size, void **owner);
|
|
static inline void gen_pool_free(struct gen_pool *pool, unsigned long addr,
|
|
size_t size)
|
|
{
|
|
gen_pool_free_owner(pool, addr, size, NULL);
|
|
}
|
|
|
|
extern void gen_pool_for_each_chunk(struct gen_pool *,
|
|
void (*)(struct gen_pool *, struct gen_pool_chunk *, void *), void *);
|
|
extern size_t gen_pool_avail(struct gen_pool *);
|
|
extern size_t gen_pool_size(struct gen_pool *);
|
|
|
|
extern void gen_pool_set_algo(struct gen_pool *pool, genpool_algo_t algo,
|
|
void *data);
|
|
|
|
extern unsigned long gen_pool_first_fit(unsigned long *map, unsigned long size,
|
|
unsigned long start, unsigned int nr, void *data,
|
|
struct gen_pool *pool, unsigned long start_addr);
|
|
|
|
extern unsigned long gen_pool_fixed_alloc(unsigned long *map,
|
|
unsigned long size, unsigned long start, unsigned int nr,
|
|
void *data, struct gen_pool *pool, unsigned long start_addr);
|
|
|
|
extern unsigned long gen_pool_first_fit_align(unsigned long *map,
|
|
unsigned long size, unsigned long start, unsigned int nr,
|
|
void *data, struct gen_pool *pool, unsigned long start_addr);
|
|
|
|
|
|
extern unsigned long gen_pool_first_fit_order_align(unsigned long *map,
|
|
unsigned long size, unsigned long start, unsigned int nr,
|
|
void *data, struct gen_pool *pool, unsigned long start_addr);
|
|
|
|
extern unsigned long gen_pool_best_fit(unsigned long *map, unsigned long size,
|
|
unsigned long start, unsigned int nr, void *data,
|
|
struct gen_pool *pool, unsigned long start_addr);
|
|
|
|
|
|
extern struct gen_pool *devm_gen_pool_create(struct device *dev,
|
|
int min_alloc_order, int nid, const char *name);
|
|
extern struct gen_pool *gen_pool_get(struct device *dev, const char *name);
|
|
|
|
extern bool gen_pool_has_addr(struct gen_pool *pool, unsigned long start,
|
|
size_t size);
|
|
|
|
#ifdef CONFIG_OF
|
|
extern struct gen_pool *of_gen_pool_get(struct device_node *np,
|
|
const char *propname, int index);
|
|
#else
|
|
static inline struct gen_pool *of_gen_pool_get(struct device_node *np,
|
|
const char *propname, int index)
|
|
{
|
|
return NULL;
|
|
}
|
|
#endif
|
|
#endif /* __GENALLOC_H__ */
|