forked from mirrors/linux
89f60a5d9b
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 */
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/*
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* Basic general purpose allocator for managing special purpose
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* memory, for example, memory that is not managed by the regular
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* kmalloc/kfree interface. Uses for this includes on-device special
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* memory, uncached memory etc.
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*
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* It is safe to use the allocator in NMI handlers and other special
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* unblockable contexts that could otherwise deadlock on locks. This
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* is implemented by using atomic operations and retries on any
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* conflicts. The disadvantage is that there may be livelocks in
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* extreme cases. For better scalability, one allocator can be used
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* for each CPU.
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*
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* The lockless operation only works if there is enough memory
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* available. If new memory is added to the pool a lock has to be
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* still taken. So any user relying on locklessness has to ensure
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* that sufficient memory is preallocated.
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*
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* The basic atomic operation of this allocator is cmpxchg on long.
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* On architectures that don't have NMI-safe cmpxchg implementation,
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* the allocator can NOT be used in NMI handler. So code uses the
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* allocator in NMI handler should depend on
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* CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG.
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*/
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#ifndef __GENALLOC_H__
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#define __GENALLOC_H__
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#include <linux/types.h>
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#include <linux/spinlock_types.h>
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#include <linux/atomic.h>
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struct device;
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struct device_node;
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struct gen_pool;
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/**
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* typedef genpool_algo_t: Allocation callback function type definition
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* @map: Pointer to bitmap
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* @size: The bitmap size in bits
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* @start: The bitnumber to start searching at
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* @nr: The number of zeroed bits we're looking for
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* @data: optional additional data used by the callback
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* @pool: the pool being allocated from
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*/
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typedef unsigned long (*genpool_algo_t)(unsigned long *map,
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unsigned long size,
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unsigned long start,
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unsigned int nr,
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void *data, struct gen_pool *pool,
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unsigned long start_addr);
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/*
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* General purpose special memory pool descriptor.
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*/
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struct gen_pool {
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spinlock_t lock;
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struct list_head chunks; /* list of chunks in this pool */
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int min_alloc_order; /* minimum allocation order */
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genpool_algo_t algo; /* allocation function */
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void *data;
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const char *name;
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};
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/*
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* General purpose special memory pool chunk descriptor.
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*/
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struct gen_pool_chunk {
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struct list_head next_chunk; /* next chunk in pool */
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atomic_long_t avail;
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phys_addr_t phys_addr; /* physical starting address of memory chunk */
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void *owner; /* private data to retrieve at alloc time */
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unsigned long start_addr; /* start address of memory chunk */
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unsigned long end_addr; /* end address of memory chunk (inclusive) */
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unsigned long bits[]; /* bitmap for allocating memory chunk */
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};
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/*
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* gen_pool data descriptor for gen_pool_first_fit_align.
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*/
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struct genpool_data_align {
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int align; /* alignment by bytes for starting address */
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};
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/*
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* gen_pool data descriptor for gen_pool_fixed_alloc.
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*/
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struct genpool_data_fixed {
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unsigned long offset; /* The offset of the specific region */
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};
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extern struct gen_pool *gen_pool_create(int, int);
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extern phys_addr_t gen_pool_virt_to_phys(struct gen_pool *pool, unsigned long);
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extern int gen_pool_add_owner(struct gen_pool *, unsigned long, phys_addr_t,
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size_t, int, void *);
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static inline int gen_pool_add_virt(struct gen_pool *pool, unsigned long addr,
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phys_addr_t phys, size_t size, int nid)
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{
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return gen_pool_add_owner(pool, addr, phys, size, nid, NULL);
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}
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/**
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* gen_pool_add - add a new chunk of special memory to the pool
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* @pool: pool to add new memory chunk to
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* @addr: starting address of memory chunk to add to pool
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* @size: size in bytes of the memory chunk to add to pool
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* @nid: node id of the node the chunk structure and bitmap should be
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* allocated on, or -1
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*
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* Add a new chunk of special memory to the specified pool.
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*
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* Returns 0 on success or a -ve errno on failure.
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*/
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static inline int gen_pool_add(struct gen_pool *pool, unsigned long addr,
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size_t size, int nid)
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{
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return gen_pool_add_virt(pool, addr, -1, size, nid);
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}
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extern void gen_pool_destroy(struct gen_pool *);
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unsigned long gen_pool_alloc_algo_owner(struct gen_pool *pool, size_t size,
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genpool_algo_t algo, void *data, void **owner);
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static inline unsigned long gen_pool_alloc_owner(struct gen_pool *pool,
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size_t size, void **owner)
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{
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return gen_pool_alloc_algo_owner(pool, size, pool->algo, pool->data,
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owner);
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}
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static inline unsigned long gen_pool_alloc_algo(struct gen_pool *pool,
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size_t size, genpool_algo_t algo, void *data)
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{
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return gen_pool_alloc_algo_owner(pool, size, algo, data, NULL);
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}
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/**
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* gen_pool_alloc - allocate special memory from the pool
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* @pool: pool to allocate from
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* @size: number of bytes to allocate from the pool
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*
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* Allocate the requested number of bytes from the specified pool.
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* Uses the pool allocation function (with first-fit algorithm by default).
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* Can not be used in NMI handler on architectures without
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* NMI-safe cmpxchg implementation.
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*/
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static inline unsigned long gen_pool_alloc(struct gen_pool *pool, size_t size)
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{
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return gen_pool_alloc_algo(pool, size, pool->algo, pool->data);
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}
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extern void *gen_pool_dma_alloc(struct gen_pool *pool, size_t size,
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dma_addr_t *dma);
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extern void *gen_pool_dma_alloc_algo(struct gen_pool *pool, size_t size,
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dma_addr_t *dma, genpool_algo_t algo, void *data);
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extern void *gen_pool_dma_alloc_align(struct gen_pool *pool, size_t size,
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dma_addr_t *dma, int align);
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extern void *gen_pool_dma_zalloc(struct gen_pool *pool, size_t size, dma_addr_t *dma);
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extern void *gen_pool_dma_zalloc_algo(struct gen_pool *pool, size_t size,
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dma_addr_t *dma, genpool_algo_t algo, void *data);
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extern void *gen_pool_dma_zalloc_align(struct gen_pool *pool, size_t size,
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dma_addr_t *dma, int align);
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extern void gen_pool_free_owner(struct gen_pool *pool, unsigned long addr,
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size_t size, void **owner);
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static inline void gen_pool_free(struct gen_pool *pool, unsigned long addr,
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size_t size)
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{
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gen_pool_free_owner(pool, addr, size, NULL);
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}
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extern void gen_pool_for_each_chunk(struct gen_pool *,
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void (*)(struct gen_pool *, struct gen_pool_chunk *, void *), void *);
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extern size_t gen_pool_avail(struct gen_pool *);
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extern size_t gen_pool_size(struct gen_pool *);
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extern void gen_pool_set_algo(struct gen_pool *pool, genpool_algo_t algo,
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void *data);
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extern unsigned long gen_pool_first_fit(unsigned long *map, unsigned long size,
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unsigned long start, unsigned int nr, void *data,
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struct gen_pool *pool, unsigned long start_addr);
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extern unsigned long gen_pool_fixed_alloc(unsigned long *map,
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unsigned long size, unsigned long start, unsigned int nr,
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void *data, struct gen_pool *pool, unsigned long start_addr);
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extern unsigned long gen_pool_first_fit_align(unsigned long *map,
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unsigned long size, unsigned long start, unsigned int nr,
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void *data, struct gen_pool *pool, unsigned long start_addr);
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extern unsigned long gen_pool_first_fit_order_align(unsigned long *map,
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unsigned long size, unsigned long start, unsigned int nr,
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void *data, struct gen_pool *pool, unsigned long start_addr);
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extern unsigned long gen_pool_best_fit(unsigned long *map, unsigned long size,
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unsigned long start, unsigned int nr, void *data,
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struct gen_pool *pool, unsigned long start_addr);
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extern struct gen_pool *devm_gen_pool_create(struct device *dev,
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int min_alloc_order, int nid, const char *name);
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extern struct gen_pool *gen_pool_get(struct device *dev, const char *name);
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extern bool gen_pool_has_addr(struct gen_pool *pool, unsigned long start,
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size_t size);
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#ifdef CONFIG_OF
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extern struct gen_pool *of_gen_pool_get(struct device_node *np,
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const char *propname, int index);
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#else
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static inline struct gen_pool *of_gen_pool_get(struct device_node *np,
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const char *propname, int index)
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{
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return NULL;
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}
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#endif
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#endif /* __GENALLOC_H__ */
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