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Diffstat (limited to 'include/linux/idr.h')
| -rw-r--r-- | include/linux/idr.h | 331 |
1 files changed, 331 insertions, 0 deletions
diff --git a/include/linux/idr.h b/include/linux/idr.h new file mode 100644 index 000000000..da5f5fa4a --- /dev/null +++ b/include/linux/idr.h @@ -0,0 +1,331 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * include/linux/idr.h + * + * 2002-10-18 written by Jim Houston jim.houston@ccur.com + * Copyright (C) 2002 by Concurrent Computer Corporation + * + * Small id to pointer translation service avoiding fixed sized + * tables. + */ + +#ifndef __IDR_H__ +#define __IDR_H__ + +#include <linux/radix-tree.h> +#include <linux/gfp.h> +#include <linux/percpu.h> + +struct idr { + struct radix_tree_root idr_rt; + unsigned int idr_base; + unsigned int idr_next; +}; + +/* + * The IDR API does not expose the tagging functionality of the radix tree + * to users. Use tag 0 to track whether a node has free space below it. + */ +#define IDR_FREE 0 + +/* Set the IDR flag and the IDR_FREE tag */ +#define IDR_RT_MARKER (ROOT_IS_IDR | (__force gfp_t) \ + (1 << (ROOT_TAG_SHIFT + IDR_FREE))) + +#define IDR_INIT_BASE(name, base) { \ + .idr_rt = RADIX_TREE_INIT(name, IDR_RT_MARKER), \ + .idr_base = (base), \ + .idr_next = 0, \ +} + +/** + * IDR_INIT() - Initialise an IDR. + * @name: Name of IDR. + * + * A freshly-initialised IDR contains no IDs. + */ +#define IDR_INIT(name) IDR_INIT_BASE(name, 0) + +/** + * DEFINE_IDR() - Define a statically-allocated IDR. + * @name: Name of IDR. + * + * An IDR defined using this macro is ready for use with no additional + * initialisation required. It contains no IDs. + */ +#define DEFINE_IDR(name) struct idr name = IDR_INIT(name) + +/** + * idr_get_cursor - Return the current position of the cyclic allocator + * @idr: idr handle + * + * The value returned is the value that will be next returned from + * idr_alloc_cyclic() if it is free (otherwise the search will start from + * this position). + */ +static inline unsigned int idr_get_cursor(const struct idr *idr) +{ + return READ_ONCE(idr->idr_next); +} + +/** + * idr_set_cursor - Set the current position of the cyclic allocator + * @idr: idr handle + * @val: new position + * + * The next call to idr_alloc_cyclic() will return @val if it is free + * (otherwise the search will start from this position). + */ +static inline void idr_set_cursor(struct idr *idr, unsigned int val) +{ + WRITE_ONCE(idr->idr_next, val); +} + +/** + * DOC: idr sync + * idr synchronization (stolen from radix-tree.h) + * + * idr_find() is able to be called locklessly, using RCU. The caller must + * ensure calls to this function are made within rcu_read_lock() regions. + * Other readers (lock-free or otherwise) and modifications may be running + * concurrently. + * + * It is still required that the caller manage the synchronization and + * lifetimes of the items. So if RCU lock-free lookups are used, typically + * this would mean that the items have their own locks, or are amenable to + * lock-free access; and that the items are freed by RCU (or only freed after + * having been deleted from the idr tree *and* a synchronize_rcu() grace + * period). + */ + +#define idr_lock(idr) xa_lock(&(idr)->idr_rt) +#define idr_unlock(idr) xa_unlock(&(idr)->idr_rt) +#define idr_lock_bh(idr) xa_lock_bh(&(idr)->idr_rt) +#define idr_unlock_bh(idr) xa_unlock_bh(&(idr)->idr_rt) +#define idr_lock_irq(idr) xa_lock_irq(&(idr)->idr_rt) +#define idr_unlock_irq(idr) xa_unlock_irq(&(idr)->idr_rt) +#define idr_lock_irqsave(idr, flags) \ + xa_lock_irqsave(&(idr)->idr_rt, flags) +#define idr_unlock_irqrestore(idr, flags) \ + xa_unlock_irqrestore(&(idr)->idr_rt, flags) + +void idr_preload(gfp_t gfp_mask); + +int idr_alloc(struct idr *, void *ptr, int start, int end, gfp_t); +int __must_check idr_alloc_u32(struct idr *, void *ptr, u32 *id, + unsigned long max, gfp_t); +int idr_alloc_cyclic(struct idr *, void *ptr, int start, int end, gfp_t); +void *idr_remove(struct idr *, unsigned long id); +void *idr_find(const struct idr *, unsigned long id); +int idr_for_each(const struct idr *, + int (*fn)(int id, void *p, void *data), void *data); +void *idr_get_next(struct idr *, int *nextid); +void *idr_get_next_ul(struct idr *, unsigned long *nextid); +void *idr_replace(struct idr *, void *, unsigned long id); +void idr_destroy(struct idr *); + +/** + * idr_init_base() - Initialise an IDR. + * @idr: IDR handle. + * @base: The base value for the IDR. + * + * This variation of idr_init() creates an IDR which will allocate IDs + * starting at %base. + */ +static inline void idr_init_base(struct idr *idr, int base) +{ + INIT_RADIX_TREE(&idr->idr_rt, IDR_RT_MARKER); + idr->idr_base = base; + idr->idr_next = 0; +} + +/** + * idr_init() - Initialise an IDR. + * @idr: IDR handle. + * + * Initialise a dynamically allocated IDR. To initialise a + * statically allocated IDR, use DEFINE_IDR(). + */ +static inline void idr_init(struct idr *idr) +{ + idr_init_base(idr, 0); +} + +/** + * idr_is_empty() - Are there any IDs allocated? + * @idr: IDR handle. + * + * Return: %true if any IDs have been allocated from this IDR. + */ +static inline bool idr_is_empty(const struct idr *idr) +{ + return radix_tree_empty(&idr->idr_rt) && + radix_tree_tagged(&idr->idr_rt, IDR_FREE); +} + +/** + * idr_preload_end - end preload section started with idr_preload() + * + * Each idr_preload() should be matched with an invocation of this + * function. See idr_preload() for details. + */ +static inline void idr_preload_end(void) +{ + local_unlock(&radix_tree_preloads.lock); +} + +/** + * idr_for_each_entry() - Iterate over an IDR's elements of a given type. + * @idr: IDR handle. + * @entry: The type * to use as cursor + * @id: Entry ID. + * + * @entry and @id do not need to be initialized before the loop, and + * after normal termination @entry is left with the value NULL. This + * is convenient for a "not found" value. + */ +#define idr_for_each_entry(idr, entry, id) \ + for (id = 0; ((entry) = idr_get_next(idr, &(id))) != NULL; id += 1U) + +/** + * idr_for_each_entry_ul() - Iterate over an IDR's elements of a given type. + * @idr: IDR handle. + * @entry: The type * to use as cursor. + * @tmp: A temporary placeholder for ID. + * @id: Entry ID. + * + * @entry and @id do not need to be initialized before the loop, and + * after normal termination @entry is left with the value NULL. This + * is convenient for a "not found" value. + */ +#define idr_for_each_entry_ul(idr, entry, tmp, id) \ + for (tmp = 0, id = 0; \ + ((entry) = tmp <= id ? idr_get_next_ul(idr, &(id)) : NULL) != NULL; \ + tmp = id, ++id) + +/** + * idr_for_each_entry_continue() - Continue iteration over an IDR's elements of a given type + * @idr: IDR handle. + * @entry: The type * to use as a cursor. + * @id: Entry ID. + * + * Continue to iterate over entries, continuing after the current position. + */ +#define idr_for_each_entry_continue(idr, entry, id) \ + for ((entry) = idr_get_next((idr), &(id)); \ + entry; \ + ++id, (entry) = idr_get_next((idr), &(id))) + +/** + * idr_for_each_entry_continue_ul() - Continue iteration over an IDR's elements of a given type + * @idr: IDR handle. + * @entry: The type * to use as a cursor. + * @tmp: A temporary placeholder for ID. + * @id: Entry ID. + * + * Continue to iterate over entries, continuing after the current position. + * After normal termination @entry is left with the value NULL. This + * is convenient for a "not found" value. + */ +#define idr_for_each_entry_continue_ul(idr, entry, tmp, id) \ + for (tmp = id; \ + ((entry) = tmp <= id ? idr_get_next_ul(idr, &(id)) : NULL) != NULL; \ + tmp = id, ++id) + +/* + * IDA - ID Allocator, use when translation from id to pointer isn't necessary. + */ +#define IDA_CHUNK_SIZE 128 /* 128 bytes per chunk */ +#define IDA_BITMAP_LONGS (IDA_CHUNK_SIZE / sizeof(long)) +#define IDA_BITMAP_BITS (IDA_BITMAP_LONGS * sizeof(long) * 8) + +struct ida_bitmap { + unsigned long bitmap[IDA_BITMAP_LONGS]; +}; + +struct ida { + struct xarray xa; +}; + +#define IDA_INIT_FLAGS (XA_FLAGS_LOCK_IRQ | XA_FLAGS_ALLOC) + +#define IDA_INIT(name) { \ + .xa = XARRAY_INIT(name, IDA_INIT_FLAGS) \ +} +#define DEFINE_IDA(name) struct ida name = IDA_INIT(name) + +int ida_alloc_range(struct ida *, unsigned int min, unsigned int max, gfp_t); +void ida_free(struct ida *, unsigned int id); +void ida_destroy(struct ida *ida); + +/** + * ida_alloc() - Allocate an unused ID. + * @ida: IDA handle. + * @gfp: Memory allocation flags. + * + * Allocate an ID between 0 and %INT_MAX, inclusive. + * + * Context: Any context. It is safe to call this function without + * locking in your code. + * Return: The allocated ID, or %-ENOMEM if memory could not be allocated, + * or %-ENOSPC if there are no free IDs. + */ +static inline int ida_alloc(struct ida *ida, gfp_t gfp) +{ + return ida_alloc_range(ida, 0, ~0, gfp); +} + +/** + * ida_alloc_min() - Allocate an unused ID. + * @ida: IDA handle. + * @min: Lowest ID to allocate. + * @gfp: Memory allocation flags. + * + * Allocate an ID between @min and %INT_MAX, inclusive. + * + * Context: Any context. It is safe to call this function without + * locking in your code. + * Return: The allocated ID, or %-ENOMEM if memory could not be allocated, + * or %-ENOSPC if there are no free IDs. + */ +static inline int ida_alloc_min(struct ida *ida, unsigned int min, gfp_t gfp) +{ + return ida_alloc_range(ida, min, ~0, gfp); +} + +/** + * ida_alloc_max() - Allocate an unused ID. + * @ida: IDA handle. + * @max: Highest ID to allocate. + * @gfp: Memory allocation flags. + * + * Allocate an ID between 0 and @max, inclusive. + * + * Context: Any context. It is safe to call this function without + * locking in your code. + * Return: The allocated ID, or %-ENOMEM if memory could not be allocated, + * or %-ENOSPC if there are no free IDs. + */ +static inline int ida_alloc_max(struct ida *ida, unsigned int max, gfp_t gfp) +{ + return ida_alloc_range(ida, 0, max, gfp); +} + +static inline void ida_init(struct ida *ida) +{ + xa_init_flags(&ida->xa, IDA_INIT_FLAGS); +} + +/* + * ida_simple_get() and ida_simple_remove() are deprecated. Use + * ida_alloc() and ida_free() instead respectively. + */ +#define ida_simple_get(ida, start, end, gfp) \ + ida_alloc_range(ida, start, (end) - 1, gfp) +#define ida_simple_remove(ida, id) ida_free(ida, id) + +static inline bool ida_is_empty(const struct ida *ida) +{ + return xa_empty(&ida->xa); +} +#endif /* __IDR_H__ */ |