diff options
Diffstat (limited to 'include/linux/idr.h')
| -rw-r--r-- | include/linux/idr.h | 170 |
1 files changed, 106 insertions, 64 deletions
diff --git a/include/linux/idr.h b/include/linux/idr.h index e5eb125effe..a6f38b5c34e 100644 --- a/include/linux/idr.h +++ b/include/linux/idr.h @@ -17,69 +17,40 @@ #include <linux/init.h> #include <linux/rcupdate.h> -#if BITS_PER_LONG == 32 -# define IDR_BITS 5 -# define IDR_FULL 0xfffffffful -/* We can only use two of the bits in the top level because there is - only one possible bit in the top level (5 bits * 7 levels = 35 - bits, but you only use 31 bits in the id). */ -# define TOP_LEVEL_FULL (IDR_FULL >> 30) -#elif BITS_PER_LONG == 64 -# define IDR_BITS 6 -# define IDR_FULL 0xfffffffffffffffful -/* We can only use two of the bits in the top level because there is - only one possible bit in the top level (6 bits * 6 levels = 36 - bits, but you only use 31 bits in the id). */ -# define TOP_LEVEL_FULL (IDR_FULL >> 62) -#else -# error "BITS_PER_LONG is not 32 or 64" -#endif - +/* + * We want shallower trees and thus more bits covered at each layer. 8 + * bits gives us large enough first layer for most use cases and maximum + * tree depth of 4. Each idr_layer is slightly larger than 2k on 64bit and + * 1k on 32bit. + */ +#define IDR_BITS 8 #define IDR_SIZE (1 << IDR_BITS) #define IDR_MASK ((1 << IDR_BITS)-1) -#define MAX_IDR_SHIFT (sizeof(int)*8 - 1) -#define MAX_IDR_BIT (1U << MAX_IDR_SHIFT) -#define MAX_IDR_MASK (MAX_IDR_BIT - 1) - -/* Leave the possibility of an incomplete final layer */ -#define MAX_IDR_LEVEL ((MAX_IDR_SHIFT + IDR_BITS - 1) / IDR_BITS) - -/* Number of id_layer structs to leave in free list */ -#define MAX_IDR_FREE (MAX_IDR_LEVEL * 2) - struct idr_layer { - unsigned long bitmap; /* A zero bit means "space here" */ + int prefix; /* the ID prefix of this idr_layer */ + DECLARE_BITMAP(bitmap, IDR_SIZE); /* A zero bit means "space here" */ struct idr_layer __rcu *ary[1<<IDR_BITS]; - int count; /* When zero, we can release it */ - int layer; /* distance from leaf */ - struct rcu_head rcu_head; + int count; /* When zero, we can release it */ + int layer; /* distance from leaf */ + struct rcu_head rcu_head; }; struct idr { - struct idr_layer __rcu *top; - struct idr_layer *id_free; - int layers; /* only valid without concurrent changes */ - int id_free_cnt; - spinlock_t lock; + struct idr_layer __rcu *hint; /* the last layer allocated from */ + struct idr_layer __rcu *top; + struct idr_layer *id_free; + int layers; /* only valid w/o concurrent changes */ + int id_free_cnt; + spinlock_t lock; }; -#define IDR_INIT(name) \ -{ \ - .top = NULL, \ - .id_free = NULL, \ - .layers = 0, \ - .id_free_cnt = 0, \ - .lock = __SPIN_LOCK_UNLOCKED(name.lock), \ +#define IDR_INIT(name) \ +{ \ + .lock = __SPIN_LOCK_UNLOCKED(name.lock), \ } #define DEFINE_IDR(name) struct idr name = IDR_INIT(name) -/* Actions to be taken after a call to _idr_sub_alloc */ -#define IDR_NEED_TO_GROW -2 -#define IDR_NOMORE_SPACE -3 - -#define _idr_rc_to_errno(rc) ((rc) == -1 ? -EAGAIN : -ENOSPC) - /** * DOC: idr sync * idr synchronization (stolen from radix-tree.h) @@ -101,19 +72,90 @@ struct idr { * This is what we export. */ -void *idr_find(struct idr *idp, int id); +void *idr_find_slowpath(struct idr *idp, int id); int idr_pre_get(struct idr *idp, gfp_t gfp_mask); -int idr_get_new(struct idr *idp, void *ptr, int *id); int idr_get_new_above(struct idr *idp, void *ptr, int starting_id, int *id); +void idr_preload(gfp_t gfp_mask); +int idr_alloc(struct idr *idp, void *ptr, int start, int end, gfp_t gfp_mask); int idr_for_each(struct idr *idp, int (*fn)(int id, void *p, void *data), void *data); void *idr_get_next(struct idr *idp, int *nextid); void *idr_replace(struct idr *idp, void *ptr, int id); void idr_remove(struct idr *idp, int id); -void idr_remove_all(struct idr *idp); +void idr_free(struct idr *idp, int id); void idr_destroy(struct idr *idp); void idr_init(struct idr *idp); +/** + * 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) +{ + preempt_enable(); +} + +/** + * idr_find - return pointer for given id + * @idp: idr handle + * @id: lookup key + * + * Return the pointer given the id it has been registered with. A %NULL + * return indicates that @id is not valid or you passed %NULL in + * idr_get_new(). + * + * This function can be called under rcu_read_lock(), given that the leaf + * pointers lifetimes are correctly managed. + */ +static inline void *idr_find(struct idr *idr, int id) +{ + struct idr_layer *hint = rcu_dereference_raw(idr->hint); + + if (hint && (id & ~IDR_MASK) == hint->prefix) + return rcu_dereference_raw(hint->ary[id & IDR_MASK]); + + return idr_find_slowpath(idr, id); +} + +/** + * idr_get_new - allocate new idr entry + * @idp: idr handle + * @ptr: pointer you want associated with the id + * @id: pointer to the allocated handle + * + * Simple wrapper around idr_get_new_above() w/ @starting_id of zero. + */ +static inline int idr_get_new(struct idr *idp, void *ptr, int *id) +{ + return idr_get_new_above(idp, ptr, 0, id); +} + +/** + * idr_for_each_entry - iterate over an idr's elements of a given type + * @idp: idr handle + * @entry: the type * to use as cursor + * @id: id entry's key + */ +#define idr_for_each_entry(idp, entry, id) \ + for (id = 0, entry = (typeof(entry))idr_get_next((idp), &(id)); \ + entry != NULL; \ + ++id, entry = (typeof(entry))idr_get_next((idp), &(id))) + +void __idr_remove_all(struct idr *idp); /* don't use */ + +/** + * idr_remove_all - remove all ids from the given idr tree + * @idp: idr handle + * + * If you're trying to destroy @idp, calling idr_destroy() is enough. + * This is going away. Don't use. + */ +static inline void __deprecated idr_remove_all(struct idr *idp) +{ + __idr_remove_all(idp); +} /* * IDA - IDR based id allocator, use when translation from id to @@ -141,7 +183,6 @@ struct ida { int ida_pre_get(struct ida *ida, gfp_t gfp_mask); int ida_get_new_above(struct ida *ida, int starting_id, int *p_id); -int ida_get_new(struct ida *ida, int *p_id); void ida_remove(struct ida *ida, int id); void ida_destroy(struct ida *ida); void ida_init(struct ida *ida); @@ -150,17 +191,18 @@ int ida_simple_get(struct ida *ida, unsigned int start, unsigned int end, gfp_t gfp_mask); void ida_simple_remove(struct ida *ida, unsigned int id); -void __init idr_init_cache(void); - /** - * idr_for_each_entry - iterate over an idr's elements of a given type - * @idp: idr handle - * @entry: the type * to use as cursor - * @id: id entry's key + * ida_get_new - allocate new ID + * @ida: idr handle + * @p_id: pointer to the allocated handle + * + * Simple wrapper around ida_get_new_above() w/ @starting_id of zero. */ -#define idr_for_each_entry(idp, entry, id) \ - for (id = 0, entry = (typeof(entry))idr_get_next((idp), &(id)); \ - entry != NULL; \ - ++id, entry = (typeof(entry))idr_get_next((idp), &(id))) +static inline int ida_get_new(struct ida *ida, int *p_id) +{ + return ida_get_new_above(ida, 0, p_id); +} + +void __init idr_init_cache(void); #endif /* __IDR_H__ */ |