]>
git.proxmox.com Git - mirror_ubuntu-bionic-kernel.git/blob - lib/idr.c
39158abebad175453b7f9f5a520300c4ac57edd8
2 * 2002-10-18 written by Jim Houston jim.houston@ccur.com
3 * Copyright (C) 2002 by Concurrent Computer Corporation
4 * Distributed under the GNU GPL license version 2.
6 * Modified by George Anzinger to reuse immediately and to use
7 * find bit instructions. Also removed _irq on spinlocks.
9 * Modified by Nadia Derbey to make it RCU safe.
11 * Small id to pointer translation service.
13 * It uses a radix tree like structure as a sparse array indexed
14 * by the id to obtain the pointer. The bitmap makes allocating
17 * You call it to allocate an id (an int) an associate with that id a
18 * pointer or what ever, we treat it as a (void *). You can pass this
19 * id to a user for him to pass back at a later time. You then pass
20 * that id to this code and it returns your pointer.
23 #ifndef TEST // to test in user space...
24 #include <linux/slab.h>
25 #include <linux/init.h>
26 #include <linux/export.h>
28 #include <linux/err.h>
29 #include <linux/string.h>
30 #include <linux/idr.h>
31 #include <linux/spinlock.h>
32 #include <linux/percpu.h>
33 #include <linux/hardirq.h>
35 #define MAX_IDR_SHIFT (sizeof(int) * 8 - 1)
36 #define MAX_IDR_BIT (1U << MAX_IDR_SHIFT)
38 /* Leave the possibility of an incomplete final layer */
39 #define MAX_IDR_LEVEL ((MAX_IDR_SHIFT + IDR_BITS - 1) / IDR_BITS)
41 /* Number of id_layer structs to leave in free list */
42 #define MAX_IDR_FREE (MAX_IDR_LEVEL * 2)
44 static struct kmem_cache
*idr_layer_cache
;
45 static DEFINE_PER_CPU(struct idr_layer
*, idr_preload_head
);
46 static DEFINE_PER_CPU(int, idr_preload_cnt
);
47 static DEFINE_SPINLOCK(simple_ida_lock
);
49 /* the maximum ID which can be allocated given idr->layers */
50 static int idr_max(int layers
)
52 int bits
= min_t(int, layers
* IDR_BITS
, MAX_IDR_SHIFT
);
54 return (1 << bits
) - 1;
58 * Prefix mask for an idr_layer at @layer. For layer 0, the prefix mask is
59 * all bits except for the lower IDR_BITS. For layer 1, 2 * IDR_BITS, and
62 static int idr_layer_prefix_mask(int layer
)
64 return ~idr_max(layer
+ 1);
67 static struct idr_layer
*get_from_free_list(struct idr
*idp
)
72 spin_lock_irqsave(&idp
->lock
, flags
);
73 if ((p
= idp
->id_free
)) {
74 idp
->id_free
= p
->ary
[0];
78 spin_unlock_irqrestore(&idp
->lock
, flags
);
83 * idr_layer_alloc - allocate a new idr_layer
84 * @gfp_mask: allocation mask
85 * @layer_idr: optional idr to allocate from
87 * If @layer_idr is %NULL, directly allocate one using @gfp_mask or fetch
88 * one from the per-cpu preload buffer. If @layer_idr is not %NULL, fetch
89 * an idr_layer from @idr->id_free.
91 * @layer_idr is to maintain backward compatibility with the old alloc
92 * interface - idr_pre_get() and idr_get_new*() - and will be removed
93 * together with per-pool preload buffer.
95 static struct idr_layer
*idr_layer_alloc(gfp_t gfp_mask
, struct idr
*layer_idr
)
97 struct idr_layer
*new;
99 /* this is the old path, bypass to get_from_free_list() */
101 return get_from_free_list(layer_idr
);
104 * Try to allocate directly from kmem_cache. We want to try this
105 * before preload buffer; otherwise, non-preloading idr_alloc()
106 * users will end up taking advantage of preloading ones. As the
107 * following is allowed to fail for preloaded cases, suppress
110 new = kmem_cache_zalloc(idr_layer_cache
, gfp_mask
| __GFP_NOWARN
);
115 * Try to fetch one from the per-cpu preload buffer if in process
116 * context. See idr_preload() for details.
118 if (!in_interrupt()) {
120 new = __this_cpu_read(idr_preload_head
);
122 __this_cpu_write(idr_preload_head
, new->ary
[0]);
123 __this_cpu_dec(idr_preload_cnt
);
132 * Both failed. Try kmem_cache again w/o adding __GFP_NOWARN so
133 * that memory allocation failure warning is printed as intended.
135 return kmem_cache_zalloc(idr_layer_cache
, gfp_mask
);
138 static void idr_layer_rcu_free(struct rcu_head
*head
)
140 struct idr_layer
*layer
;
142 layer
= container_of(head
, struct idr_layer
, rcu_head
);
143 kmem_cache_free(idr_layer_cache
, layer
);
146 static inline void free_layer(struct idr
*idr
, struct idr_layer
*p
)
149 RCU_INIT_POINTER(idr
->hint
, NULL
);
150 call_rcu(&p
->rcu_head
, idr_layer_rcu_free
);
153 /* only called when idp->lock is held */
154 static void __move_to_free_list(struct idr
*idp
, struct idr_layer
*p
)
156 p
->ary
[0] = idp
->id_free
;
161 static void move_to_free_list(struct idr
*idp
, struct idr_layer
*p
)
166 * Depends on the return element being zeroed.
168 spin_lock_irqsave(&idp
->lock
, flags
);
169 __move_to_free_list(idp
, p
);
170 spin_unlock_irqrestore(&idp
->lock
, flags
);
173 static void idr_mark_full(struct idr_layer
**pa
, int id
)
175 struct idr_layer
*p
= pa
[0];
178 __set_bit(id
& IDR_MASK
, p
->bitmap
);
180 * If this layer is full mark the bit in the layer above to
181 * show that this part of the radix tree is full. This may
182 * complete the layer above and require walking up the radix
185 while (bitmap_full(p
->bitmap
, IDR_SIZE
)) {
189 __set_bit((id
& IDR_MASK
), p
->bitmap
);
193 static int __idr_pre_get(struct idr
*idp
, gfp_t gfp_mask
)
195 while (idp
->id_free_cnt
< MAX_IDR_FREE
) {
196 struct idr_layer
*new;
197 new = kmem_cache_zalloc(idr_layer_cache
, gfp_mask
);
200 move_to_free_list(idp
, new);
206 * sub_alloc - try to allocate an id without growing the tree depth
208 * @starting_id: id to start search at
209 * @pa: idr_layer[MAX_IDR_LEVEL] used as backtrack buffer
210 * @gfp_mask: allocation mask for idr_layer_alloc()
211 * @layer_idr: optional idr passed to idr_layer_alloc()
213 * Allocate an id in range [@starting_id, INT_MAX] from @idp without
214 * growing its depth. Returns
216 * the allocated id >= 0 if successful,
217 * -EAGAIN if the tree needs to grow for allocation to succeed,
218 * -ENOSPC if the id space is exhausted,
219 * -ENOMEM if more idr_layers need to be allocated.
221 static int sub_alloc(struct idr
*idp
, int *starting_id
, struct idr_layer
**pa
,
222 gfp_t gfp_mask
, struct idr
*layer_idr
)
225 struct idr_layer
*p
, *new;
235 * We run around this while until we reach the leaf node...
237 n
= (id
>> (IDR_BITS
*l
)) & IDR_MASK
;
238 m
= find_next_zero_bit(p
->bitmap
, IDR_SIZE
, n
);
240 /* no space available go back to previous layer. */
243 id
= (id
| ((1 << (IDR_BITS
* l
)) - 1)) + 1;
245 /* if already at the top layer, we need to grow */
246 if (id
> idr_max(idp
->layers
)) {
253 /* If we need to go up one layer, continue the
254 * loop; otherwise, restart from the top.
256 sh
= IDR_BITS
* (l
+ 1);
257 if (oid
>> sh
== id
>> sh
)
264 id
= ((id
>> sh
) ^ n
^ m
) << sh
;
266 if ((id
>= MAX_IDR_BIT
) || (id
< 0))
271 * Create the layer below if it is missing.
274 new = idr_layer_alloc(gfp_mask
, layer_idr
);
278 new->prefix
= id
& idr_layer_prefix_mask(new->layer
);
279 rcu_assign_pointer(p
->ary
[m
], new);
290 static int idr_get_empty_slot(struct idr
*idp
, int starting_id
,
291 struct idr_layer
**pa
, gfp_t gfp_mask
,
292 struct idr
*layer_idr
)
294 struct idr_layer
*p
, *new;
301 layers
= idp
->layers
;
303 if (!(p
= idr_layer_alloc(gfp_mask
, layer_idr
)))
309 * Add a new layer to the top of the tree if the requested
310 * id is larger than the currently allocated space.
312 while (id
> idr_max(layers
)) {
315 /* special case: if the tree is currently empty,
316 * then we grow the tree by moving the top node
320 WARN_ON_ONCE(p
->prefix
);
323 if (!(new = idr_layer_alloc(gfp_mask
, layer_idr
))) {
325 * The allocation failed. If we built part of
326 * the structure tear it down.
328 spin_lock_irqsave(&idp
->lock
, flags
);
329 for (new = p
; p
&& p
!= idp
->top
; new = p
) {
333 bitmap_clear(new->bitmap
, 0, IDR_SIZE
);
334 __move_to_free_list(idp
, new);
336 spin_unlock_irqrestore(&idp
->lock
, flags
);
341 new->layer
= layers
-1;
342 new->prefix
= id
& idr_layer_prefix_mask(new->layer
);
343 if (bitmap_full(p
->bitmap
, IDR_SIZE
))
344 __set_bit(0, new->bitmap
);
347 rcu_assign_pointer(idp
->top
, p
);
348 idp
->layers
= layers
;
349 v
= sub_alloc(idp
, &id
, pa
, gfp_mask
, layer_idr
);
356 * @id and @pa are from a successful allocation from idr_get_empty_slot().
357 * Install the user pointer @ptr and mark the slot full.
359 static void idr_fill_slot(struct idr
*idr
, void *ptr
, int id
,
360 struct idr_layer
**pa
)
362 /* update hint used for lookup, cleared from free_layer() */
363 rcu_assign_pointer(idr
->hint
, pa
[0]);
365 rcu_assign_pointer(pa
[0]->ary
[id
& IDR_MASK
], (struct idr_layer
*)ptr
);
367 idr_mark_full(pa
, id
);
372 * idr_preload - preload for idr_alloc()
373 * @gfp_mask: allocation mask to use for preloading
375 * Preload per-cpu layer buffer for idr_alloc(). Can only be used from
376 * process context and each idr_preload() invocation should be matched with
377 * idr_preload_end(). Note that preemption is disabled while preloaded.
379 * The first idr_alloc() in the preloaded section can be treated as if it
380 * were invoked with @gfp_mask used for preloading. This allows using more
381 * permissive allocation masks for idrs protected by spinlocks.
383 * For example, if idr_alloc() below fails, the failure can be treated as
384 * if idr_alloc() were called with GFP_KERNEL rather than GFP_NOWAIT.
386 * idr_preload(GFP_KERNEL);
389 * id = idr_alloc(idr, ptr, start, end, GFP_NOWAIT);
396 void idr_preload(gfp_t gfp_mask
)
399 * Consuming preload buffer from non-process context breaks preload
400 * allocation guarantee. Disallow usage from those contexts.
402 WARN_ON_ONCE(in_interrupt());
403 might_sleep_if(gfp_mask
& __GFP_WAIT
);
408 * idr_alloc() is likely to succeed w/o full idr_layer buffer and
409 * return value from idr_alloc() needs to be checked for failure
410 * anyway. Silently give up if allocation fails. The caller can
411 * treat failures from idr_alloc() as if idr_alloc() were called
412 * with @gfp_mask which should be enough.
414 while (__this_cpu_read(idr_preload_cnt
) < MAX_IDR_FREE
) {
415 struct idr_layer
*new;
418 new = kmem_cache_zalloc(idr_layer_cache
, gfp_mask
);
423 /* link the new one to per-cpu preload list */
424 new->ary
[0] = __this_cpu_read(idr_preload_head
);
425 __this_cpu_write(idr_preload_head
, new);
426 __this_cpu_inc(idr_preload_cnt
);
429 EXPORT_SYMBOL(idr_preload
);
432 * idr_alloc - allocate new idr entry
433 * @idr: the (initialized) idr
434 * @ptr: pointer to be associated with the new id
435 * @start: the minimum id (inclusive)
436 * @end: the maximum id (exclusive, <= 0 for max)
437 * @gfp_mask: memory allocation flags
439 * Allocate an id in [start, end) and associate it with @ptr. If no ID is
440 * available in the specified range, returns -ENOSPC. On memory allocation
441 * failure, returns -ENOMEM.
443 * Note that @end is treated as max when <= 0. This is to always allow
444 * using @start + N as @end as long as N is inside integer range.
446 * The user is responsible for exclusively synchronizing all operations
447 * which may modify @idr. However, read-only accesses such as idr_find()
448 * or iteration can be performed under RCU read lock provided the user
449 * destroys @ptr in RCU-safe way after removal from idr.
451 int idr_alloc(struct idr
*idr
, void *ptr
, int start
, int end
, gfp_t gfp_mask
)
453 int max
= end
> 0 ? end
- 1 : INT_MAX
; /* inclusive upper limit */
454 struct idr_layer
*pa
[MAX_IDR_LEVEL
+ 1];
457 might_sleep_if(gfp_mask
& __GFP_WAIT
);
460 if (WARN_ON_ONCE(start
< 0))
462 if (unlikely(max
< start
))
466 id
= idr_get_empty_slot(idr
, start
, pa
, gfp_mask
, NULL
);
467 if (unlikely(id
< 0))
469 if (unlikely(id
> max
))
472 idr_fill_slot(idr
, ptr
, id
, pa
);
475 EXPORT_SYMBOL_GPL(idr_alloc
);
478 * idr_alloc_cyclic - allocate new idr entry in a cyclical fashion
479 * @idr: the (initialized) idr
480 * @ptr: pointer to be associated with the new id
481 * @start: the minimum id (inclusive)
482 * @end: the maximum id (exclusive, <= 0 for max)
483 * @gfp_mask: memory allocation flags
485 * Essentially the same as idr_alloc, but prefers to allocate progressively
486 * higher ids if it can. If the "cur" counter wraps, then it will start again
487 * at the "start" end of the range and allocate one that has already been used.
489 int idr_alloc_cyclic(struct idr
*idr
, void *ptr
, int start
, int end
,
494 id
= idr_alloc(idr
, ptr
, max(start
, idr
->cur
), end
, gfp_mask
);
496 id
= idr_alloc(idr
, ptr
, start
, end
, gfp_mask
);
502 EXPORT_SYMBOL(idr_alloc_cyclic
);
504 static void idr_remove_warning(int id
)
506 WARN(1, "idr_remove called for id=%d which is not allocated.\n", id
);
509 static void sub_remove(struct idr
*idp
, int shift
, int id
)
511 struct idr_layer
*p
= idp
->top
;
512 struct idr_layer
**pa
[MAX_IDR_LEVEL
+ 1];
513 struct idr_layer
***paa
= &pa
[0];
514 struct idr_layer
*to_free
;
520 while ((shift
> 0) && p
) {
521 n
= (id
>> shift
) & IDR_MASK
;
522 __clear_bit(n
, p
->bitmap
);
528 if (likely(p
!= NULL
&& test_bit(n
, p
->bitmap
))) {
529 __clear_bit(n
, p
->bitmap
);
530 RCU_INIT_POINTER(p
->ary
[n
], NULL
);
532 while(*paa
&& ! --((**paa
)->count
)){
534 free_layer(idp
, to_free
);
541 free_layer(idp
, to_free
);
543 idr_remove_warning(id
);
547 * idr_remove - remove the given id and free its slot
551 void idr_remove(struct idr
*idp
, int id
)
554 struct idr_layer
*to_free
;
559 if (id
> idr_max(idp
->layers
)) {
560 idr_remove_warning(id
);
564 sub_remove(idp
, (idp
->layers
- 1) * IDR_BITS
, id
);
565 if (idp
->top
&& idp
->top
->count
== 1 && (idp
->layers
> 1) &&
568 * Single child at leftmost slot: we can shrink the tree.
569 * This level is not needed anymore since when layers are
570 * inserted, they are inserted at the top of the existing
574 p
= idp
->top
->ary
[0];
575 rcu_assign_pointer(idp
->top
, p
);
578 bitmap_clear(to_free
->bitmap
, 0, IDR_SIZE
);
579 free_layer(idp
, to_free
);
582 EXPORT_SYMBOL(idr_remove
);
584 static void __idr_remove_all(struct idr
*idp
)
589 struct idr_layer
*pa
[MAX_IDR_LEVEL
+ 1];
590 struct idr_layer
**paa
= &pa
[0];
592 n
= idp
->layers
* IDR_BITS
;
594 RCU_INIT_POINTER(idp
->top
, NULL
);
595 max
= idr_max(idp
->layers
);
598 while (id
>= 0 && id
<= max
) {
599 while (n
> IDR_BITS
&& p
) {
602 p
= p
->ary
[(id
>> n
) & IDR_MASK
];
607 /* Get the highest bit that the above add changed from 0->1. */
608 while (n
< fls(id
^ bt_mask
)) {
619 * idr_destroy - release all cached layers within an idr tree
622 * Free all id mappings and all idp_layers. After this function, @idp is
623 * completely unused and can be freed / recycled. The caller is
624 * responsible for ensuring that no one else accesses @idp during or after
627 * A typical clean-up sequence for objects stored in an idr tree will use
628 * idr_for_each() to free all objects, if necessay, then idr_destroy() to
629 * free up the id mappings and cached idr_layers.
631 void idr_destroy(struct idr
*idp
)
633 __idr_remove_all(idp
);
635 while (idp
->id_free_cnt
) {
636 struct idr_layer
*p
= get_from_free_list(idp
);
637 kmem_cache_free(idr_layer_cache
, p
);
640 EXPORT_SYMBOL(idr_destroy
);
642 void *idr_find_slowpath(struct idr
*idp
, int id
)
650 p
= rcu_dereference_raw(idp
->top
);
653 n
= (p
->layer
+1) * IDR_BITS
;
655 if (id
> idr_max(p
->layer
+ 1))
661 BUG_ON(n
!= p
->layer
*IDR_BITS
);
662 p
= rcu_dereference_raw(p
->ary
[(id
>> n
) & IDR_MASK
]);
666 EXPORT_SYMBOL(idr_find_slowpath
);
669 * idr_for_each - iterate through all stored pointers
671 * @fn: function to be called for each pointer
672 * @data: data passed back to callback function
674 * Iterate over the pointers registered with the given idr. The
675 * callback function will be called for each pointer currently
676 * registered, passing the id, the pointer and the data pointer passed
677 * to this function. It is not safe to modify the idr tree while in
678 * the callback, so functions such as idr_get_new and idr_remove are
681 * We check the return of @fn each time. If it returns anything other
682 * than %0, we break out and return that value.
684 * The caller must serialize idr_for_each() vs idr_get_new() and idr_remove().
686 int idr_for_each(struct idr
*idp
,
687 int (*fn
)(int id
, void *p
, void *data
), void *data
)
689 int n
, id
, max
, error
= 0;
691 struct idr_layer
*pa
[MAX_IDR_LEVEL
+ 1];
692 struct idr_layer
**paa
= &pa
[0];
694 n
= idp
->layers
* IDR_BITS
;
695 p
= rcu_dereference_raw(idp
->top
);
696 max
= idr_max(idp
->layers
);
699 while (id
>= 0 && id
<= max
) {
703 p
= rcu_dereference_raw(p
->ary
[(id
>> n
) & IDR_MASK
]);
707 error
= fn(id
, (void *)p
, data
);
713 while (n
< fls(id
)) {
721 EXPORT_SYMBOL(idr_for_each
);
724 * idr_get_next - lookup next object of id to given id.
726 * @nextidp: pointer to lookup key
728 * Returns pointer to registered object with id, which is next number to
729 * given id. After being looked up, *@nextidp will be updated for the next
732 * This function can be called under rcu_read_lock(), given that the leaf
733 * pointers lifetimes are correctly managed.
735 void *idr_get_next(struct idr
*idp
, int *nextidp
)
737 struct idr_layer
*p
, *pa
[MAX_IDR_LEVEL
+ 1];
738 struct idr_layer
**paa
= &pa
[0];
743 p
= rcu_dereference_raw(idp
->top
);
746 n
= (p
->layer
+ 1) * IDR_BITS
;
747 max
= idr_max(p
->layer
+ 1);
749 while (id
>= 0 && id
<= max
) {
753 p
= rcu_dereference_raw(p
->ary
[(id
>> n
) & IDR_MASK
]);
762 * Proceed to the next layer at the current level. Unlike
763 * idr_for_each(), @id isn't guaranteed to be aligned to
764 * layer boundary at this point and adding 1 << n may
765 * incorrectly skip IDs. Make sure we jump to the
766 * beginning of the next layer using round_up().
768 id
= round_up(id
+ 1, 1 << n
);
769 while (n
< fls(id
)) {
776 EXPORT_SYMBOL(idr_get_next
);
780 * idr_replace - replace pointer for given id
782 * @ptr: pointer you want associated with the id
785 * Replace the pointer registered with an id and return the old value.
786 * A %-ENOENT return indicates that @id was not found.
787 * A %-EINVAL return indicates that @id was not within valid constraints.
789 * The caller must serialize with writers.
791 void *idr_replace(struct idr
*idp
, void *ptr
, int id
)
794 struct idr_layer
*p
, *old_p
;
797 return ERR_PTR(-EINVAL
);
801 return ERR_PTR(-ENOENT
);
803 if (id
> idr_max(p
->layer
+ 1))
804 return ERR_PTR(-ENOENT
);
806 n
= p
->layer
* IDR_BITS
;
807 while ((n
> 0) && p
) {
808 p
= p
->ary
[(id
>> n
) & IDR_MASK
];
813 if (unlikely(p
== NULL
|| !test_bit(n
, p
->bitmap
)))
814 return ERR_PTR(-ENOENT
);
817 rcu_assign_pointer(p
->ary
[n
], ptr
);
821 EXPORT_SYMBOL(idr_replace
);
823 void __init
idr_init_cache(void)
825 idr_layer_cache
= kmem_cache_create("idr_layer_cache",
826 sizeof(struct idr_layer
), 0, SLAB_PANIC
, NULL
);
830 * idr_init - initialize idr handle
833 * This function is use to set up the handle (@idp) that you will pass
834 * to the rest of the functions.
836 void idr_init(struct idr
*idp
)
838 memset(idp
, 0, sizeof(struct idr
));
839 spin_lock_init(&idp
->lock
);
841 EXPORT_SYMBOL(idr_init
);
843 static int idr_has_entry(int id
, void *p
, void *data
)
848 bool idr_is_empty(struct idr
*idp
)
850 return !idr_for_each(idp
, idr_has_entry
, NULL
);
852 EXPORT_SYMBOL(idr_is_empty
);
855 * DOC: IDA description
856 * IDA - IDR based ID allocator
858 * This is id allocator without id -> pointer translation. Memory
859 * usage is much lower than full blown idr because each id only
860 * occupies a bit. ida uses a custom leaf node which contains
861 * IDA_BITMAP_BITS slots.
863 * 2007-04-25 written by Tejun Heo <htejun@gmail.com>
866 static void free_bitmap(struct ida
*ida
, struct ida_bitmap
*bitmap
)
870 if (!ida
->free_bitmap
) {
871 spin_lock_irqsave(&ida
->idr
.lock
, flags
);
872 if (!ida
->free_bitmap
) {
873 ida
->free_bitmap
= bitmap
;
876 spin_unlock_irqrestore(&ida
->idr
.lock
, flags
);
883 * ida_pre_get - reserve resources for ida allocation
885 * @gfp_mask: memory allocation flag
887 * This function should be called prior to locking and calling the
888 * following function. It preallocates enough memory to satisfy the
889 * worst possible allocation.
891 * If the system is REALLY out of memory this function returns %0,
894 int ida_pre_get(struct ida
*ida
, gfp_t gfp_mask
)
896 /* allocate idr_layers */
897 if (!__idr_pre_get(&ida
->idr
, gfp_mask
))
900 /* allocate free_bitmap */
901 if (!ida
->free_bitmap
) {
902 struct ida_bitmap
*bitmap
;
904 bitmap
= kmalloc(sizeof(struct ida_bitmap
), gfp_mask
);
908 free_bitmap(ida
, bitmap
);
913 EXPORT_SYMBOL(ida_pre_get
);
916 * ida_get_new_above - allocate new ID above or equal to a start id
918 * @starting_id: id to start search at
919 * @p_id: pointer to the allocated handle
921 * Allocate new ID above or equal to @starting_id. It should be called
922 * with any required locks.
924 * If memory is required, it will return %-EAGAIN, you should unlock
925 * and go back to the ida_pre_get() call. If the ida is full, it will
928 * @p_id returns a value in the range @starting_id ... %0x7fffffff.
930 int ida_get_new_above(struct ida
*ida
, int starting_id
, int *p_id
)
932 struct idr_layer
*pa
[MAX_IDR_LEVEL
+ 1];
933 struct ida_bitmap
*bitmap
;
935 int idr_id
= starting_id
/ IDA_BITMAP_BITS
;
936 int offset
= starting_id
% IDA_BITMAP_BITS
;
940 /* get vacant slot */
941 t
= idr_get_empty_slot(&ida
->idr
, idr_id
, pa
, 0, &ida
->idr
);
943 return t
== -ENOMEM
? -EAGAIN
: t
;
945 if (t
* IDA_BITMAP_BITS
>= MAX_IDR_BIT
)
952 /* if bitmap isn't there, create a new one */
953 bitmap
= (void *)pa
[0]->ary
[idr_id
& IDR_MASK
];
955 spin_lock_irqsave(&ida
->idr
.lock
, flags
);
956 bitmap
= ida
->free_bitmap
;
957 ida
->free_bitmap
= NULL
;
958 spin_unlock_irqrestore(&ida
->idr
.lock
, flags
);
963 memset(bitmap
, 0, sizeof(struct ida_bitmap
));
964 rcu_assign_pointer(pa
[0]->ary
[idr_id
& IDR_MASK
],
969 /* lookup for empty slot */
970 t
= find_next_zero_bit(bitmap
->bitmap
, IDA_BITMAP_BITS
, offset
);
971 if (t
== IDA_BITMAP_BITS
) {
972 /* no empty slot after offset, continue to the next chunk */
978 id
= idr_id
* IDA_BITMAP_BITS
+ t
;
979 if (id
>= MAX_IDR_BIT
)
982 __set_bit(t
, bitmap
->bitmap
);
983 if (++bitmap
->nr_busy
== IDA_BITMAP_BITS
)
984 idr_mark_full(pa
, idr_id
);
988 /* Each leaf node can handle nearly a thousand slots and the
989 * whole idea of ida is to have small memory foot print.
990 * Throw away extra resources one by one after each successful
993 if (ida
->idr
.id_free_cnt
|| ida
->free_bitmap
) {
994 struct idr_layer
*p
= get_from_free_list(&ida
->idr
);
996 kmem_cache_free(idr_layer_cache
, p
);
1001 EXPORT_SYMBOL(ida_get_new_above
);
1004 * ida_remove - remove the given ID
1008 void ida_remove(struct ida
*ida
, int id
)
1010 struct idr_layer
*p
= ida
->idr
.top
;
1011 int shift
= (ida
->idr
.layers
- 1) * IDR_BITS
;
1012 int idr_id
= id
/ IDA_BITMAP_BITS
;
1013 int offset
= id
% IDA_BITMAP_BITS
;
1015 struct ida_bitmap
*bitmap
;
1017 if (idr_id
> idr_max(ida
->idr
.layers
))
1020 /* clear full bits while looking up the leaf idr_layer */
1021 while ((shift
> 0) && p
) {
1022 n
= (idr_id
>> shift
) & IDR_MASK
;
1023 __clear_bit(n
, p
->bitmap
);
1031 n
= idr_id
& IDR_MASK
;
1032 __clear_bit(n
, p
->bitmap
);
1034 bitmap
= (void *)p
->ary
[n
];
1035 if (!bitmap
|| !test_bit(offset
, bitmap
->bitmap
))
1038 /* update bitmap and remove it if empty */
1039 __clear_bit(offset
, bitmap
->bitmap
);
1040 if (--bitmap
->nr_busy
== 0) {
1041 __set_bit(n
, p
->bitmap
); /* to please idr_remove() */
1042 idr_remove(&ida
->idr
, idr_id
);
1043 free_bitmap(ida
, bitmap
);
1049 WARN(1, "ida_remove called for id=%d which is not allocated.\n", id
);
1051 EXPORT_SYMBOL(ida_remove
);
1054 * ida_destroy - release all cached layers within an ida tree
1057 void ida_destroy(struct ida
*ida
)
1059 idr_destroy(&ida
->idr
);
1060 kfree(ida
->free_bitmap
);
1062 EXPORT_SYMBOL(ida_destroy
);
1065 * ida_simple_get - get a new id.
1066 * @ida: the (initialized) ida.
1067 * @start: the minimum id (inclusive, < 0x8000000)
1068 * @end: the maximum id (exclusive, < 0x8000000 or 0)
1069 * @gfp_mask: memory allocation flags
1071 * Allocates an id in the range start <= id < end, or returns -ENOSPC.
1072 * On memory allocation failure, returns -ENOMEM.
1074 * Use ida_simple_remove() to get rid of an id.
1076 int ida_simple_get(struct ida
*ida
, unsigned int start
, unsigned int end
,
1081 unsigned long flags
;
1083 BUG_ON((int)start
< 0);
1084 BUG_ON((int)end
< 0);
1089 BUG_ON(end
< start
);
1094 if (!ida_pre_get(ida
, gfp_mask
))
1097 spin_lock_irqsave(&simple_ida_lock
, flags
);
1098 ret
= ida_get_new_above(ida
, start
, &id
);
1101 ida_remove(ida
, id
);
1107 spin_unlock_irqrestore(&simple_ida_lock
, flags
);
1109 if (unlikely(ret
== -EAGAIN
))
1114 EXPORT_SYMBOL(ida_simple_get
);
1117 * ida_simple_remove - remove an allocated id.
1118 * @ida: the (initialized) ida.
1119 * @id: the id returned by ida_simple_get.
1121 void ida_simple_remove(struct ida
*ida
, unsigned int id
)
1123 unsigned long flags
;
1125 BUG_ON((int)id
< 0);
1126 spin_lock_irqsave(&simple_ida_lock
, flags
);
1127 ida_remove(ida
, id
);
1128 spin_unlock_irqrestore(&simple_ida_lock
, flags
);
1130 EXPORT_SYMBOL(ida_simple_remove
);
1133 * ida_init - initialize ida handle
1136 * This function is use to set up the handle (@ida) that you will pass
1137 * to the rest of the functions.
1139 void ida_init(struct ida
*ida
)
1141 memset(ida
, 0, sizeof(struct ida
));
1142 idr_init(&ida
->idr
);
1145 EXPORT_SYMBOL(ida_init
);