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git.proxmox.com Git - mirror_ubuntu-eoan-kernel.git/blob - lib/idr.c
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>
34 #define MAX_IDR_SHIFT (sizeof(int) * 8 - 1)
35 #define MAX_IDR_BIT (1U << MAX_IDR_SHIFT)
37 /* Leave the possibility of an incomplete final layer */
38 #define MAX_IDR_LEVEL ((MAX_IDR_SHIFT + IDR_BITS - 1) / IDR_BITS)
40 /* Number of id_layer structs to leave in free list */
41 #define MAX_IDR_FREE (MAX_IDR_LEVEL * 2)
43 static struct kmem_cache
*idr_layer_cache
;
44 static DEFINE_PER_CPU(struct idr_layer
*, idr_preload_head
);
45 static DEFINE_PER_CPU(int, idr_preload_cnt
);
46 static DEFINE_SPINLOCK(simple_ida_lock
);
48 /* the maximum ID which can be allocated given idr->layers */
49 static int idr_max(int layers
)
51 int bits
= min_t(int, layers
* IDR_BITS
, MAX_IDR_SHIFT
);
53 return (1 << bits
) - 1;
57 * Prefix mask for an idr_layer at @layer. For layer 0, the prefix mask is
58 * all bits except for the lower IDR_BITS. For layer 1, 2 * IDR_BITS, and
61 static int idr_layer_prefix_mask(int layer
)
63 return ~idr_max(layer
+ 1);
66 static struct idr_layer
*get_from_free_list(struct idr
*idp
)
71 spin_lock_irqsave(&idp
->lock
, flags
);
72 if ((p
= idp
->id_free
)) {
73 idp
->id_free
= p
->ary
[0];
77 spin_unlock_irqrestore(&idp
->lock
, flags
);
82 * idr_layer_alloc - allocate a new idr_layer
83 * @gfp_mask: allocation mask
84 * @layer_idr: optional idr to allocate from
86 * If @layer_idr is %NULL, directly allocate one using @gfp_mask or fetch
87 * one from the per-cpu preload buffer. If @layer_idr is not %NULL, fetch
88 * an idr_layer from @idr->id_free.
90 * @layer_idr is to maintain backward compatibility with the old alloc
91 * interface - idr_pre_get() and idr_get_new*() - and will be removed
92 * together with per-pool preload buffer.
94 static struct idr_layer
*idr_layer_alloc(gfp_t gfp_mask
, struct idr
*layer_idr
)
96 struct idr_layer
*new;
98 /* this is the old path, bypass to get_from_free_list() */
100 return get_from_free_list(layer_idr
);
103 * Try to allocate directly from kmem_cache. We want to try this
104 * before preload buffer; otherwise, non-preloading idr_alloc()
105 * users will end up taking advantage of preloading ones. As the
106 * following is allowed to fail for preloaded cases, suppress
109 new = kmem_cache_zalloc(idr_layer_cache
, gfp_mask
| __GFP_NOWARN
);
114 * Try to fetch one from the per-cpu preload buffer if in process
115 * context. See idr_preload() for details.
117 if (!in_interrupt()) {
119 new = __this_cpu_read(idr_preload_head
);
121 __this_cpu_write(idr_preload_head
, new->ary
[0]);
122 __this_cpu_dec(idr_preload_cnt
);
131 * Both failed. Try kmem_cache again w/o adding __GFP_NOWARN so
132 * that memory allocation failure warning is printed as intended.
134 return kmem_cache_zalloc(idr_layer_cache
, gfp_mask
);
137 static void idr_layer_rcu_free(struct rcu_head
*head
)
139 struct idr_layer
*layer
;
141 layer
= container_of(head
, struct idr_layer
, rcu_head
);
142 kmem_cache_free(idr_layer_cache
, layer
);
145 static inline void free_layer(struct idr
*idr
, struct idr_layer
*p
)
148 RCU_INIT_POINTER(idr
->hint
, NULL
);
149 call_rcu(&p
->rcu_head
, idr_layer_rcu_free
);
152 /* only called when idp->lock is held */
153 static void __move_to_free_list(struct idr
*idp
, struct idr_layer
*p
)
155 p
->ary
[0] = idp
->id_free
;
160 static void move_to_free_list(struct idr
*idp
, struct idr_layer
*p
)
165 * Depends on the return element being zeroed.
167 spin_lock_irqsave(&idp
->lock
, flags
);
168 __move_to_free_list(idp
, p
);
169 spin_unlock_irqrestore(&idp
->lock
, flags
);
172 static void idr_mark_full(struct idr_layer
**pa
, int id
)
174 struct idr_layer
*p
= pa
[0];
177 __set_bit(id
& IDR_MASK
, p
->bitmap
);
179 * If this layer is full mark the bit in the layer above to
180 * show that this part of the radix tree is full. This may
181 * complete the layer above and require walking up the radix
184 while (bitmap_full(p
->bitmap
, IDR_SIZE
)) {
188 __set_bit((id
& IDR_MASK
), p
->bitmap
);
192 static int __idr_pre_get(struct idr
*idp
, gfp_t gfp_mask
)
194 while (idp
->id_free_cnt
< MAX_IDR_FREE
) {
195 struct idr_layer
*new;
196 new = kmem_cache_zalloc(idr_layer_cache
, gfp_mask
);
199 move_to_free_list(idp
, new);
205 * sub_alloc - try to allocate an id without growing the tree depth
207 * @starting_id: id to start search at
208 * @pa: idr_layer[MAX_IDR_LEVEL] used as backtrack buffer
209 * @gfp_mask: allocation mask for idr_layer_alloc()
210 * @layer_idr: optional idr passed to idr_layer_alloc()
212 * Allocate an id in range [@starting_id, INT_MAX] from @idp without
213 * growing its depth. Returns
215 * the allocated id >= 0 if successful,
216 * -EAGAIN if the tree needs to grow for allocation to succeed,
217 * -ENOSPC if the id space is exhausted,
218 * -ENOMEM if more idr_layers need to be allocated.
220 static int sub_alloc(struct idr
*idp
, int *starting_id
, struct idr_layer
**pa
,
221 gfp_t gfp_mask
, struct idr
*layer_idr
)
224 struct idr_layer
*p
, *new;
234 * We run around this while until we reach the leaf node...
236 n
= (id
>> (IDR_BITS
*l
)) & IDR_MASK
;
237 m
= find_next_zero_bit(p
->bitmap
, IDR_SIZE
, n
);
239 /* no space available go back to previous layer. */
242 id
= (id
| ((1 << (IDR_BITS
* l
)) - 1)) + 1;
244 /* if already at the top layer, we need to grow */
245 if (id
> idr_max(idp
->layers
)) {
252 /* If we need to go up one layer, continue the
253 * loop; otherwise, restart from the top.
255 sh
= IDR_BITS
* (l
+ 1);
256 if (oid
>> sh
== id
>> sh
)
263 id
= ((id
>> sh
) ^ n
^ m
) << sh
;
265 if ((id
>= MAX_IDR_BIT
) || (id
< 0))
270 * Create the layer below if it is missing.
273 new = idr_layer_alloc(gfp_mask
, layer_idr
);
277 new->prefix
= id
& idr_layer_prefix_mask(new->layer
);
278 rcu_assign_pointer(p
->ary
[m
], new);
289 static int idr_get_empty_slot(struct idr
*idp
, int starting_id
,
290 struct idr_layer
**pa
, gfp_t gfp_mask
,
291 struct idr
*layer_idr
)
293 struct idr_layer
*p
, *new;
300 layers
= idp
->layers
;
302 if (!(p
= idr_layer_alloc(gfp_mask
, layer_idr
)))
308 * Add a new layer to the top of the tree if the requested
309 * id is larger than the currently allocated space.
311 while (id
> idr_max(layers
)) {
314 /* special case: if the tree is currently empty,
315 * then we grow the tree by moving the top node
319 WARN_ON_ONCE(p
->prefix
);
322 if (!(new = idr_layer_alloc(gfp_mask
, layer_idr
))) {
324 * The allocation failed. If we built part of
325 * the structure tear it down.
327 spin_lock_irqsave(&idp
->lock
, flags
);
328 for (new = p
; p
&& p
!= idp
->top
; new = p
) {
332 bitmap_clear(new->bitmap
, 0, IDR_SIZE
);
333 __move_to_free_list(idp
, new);
335 spin_unlock_irqrestore(&idp
->lock
, flags
);
340 new->layer
= layers
-1;
341 new->prefix
= id
& idr_layer_prefix_mask(new->layer
);
342 if (bitmap_full(p
->bitmap
, IDR_SIZE
))
343 __set_bit(0, new->bitmap
);
346 rcu_assign_pointer(idp
->top
, p
);
347 idp
->layers
= layers
;
348 v
= sub_alloc(idp
, &id
, pa
, gfp_mask
, layer_idr
);
355 * @id and @pa are from a successful allocation from idr_get_empty_slot().
356 * Install the user pointer @ptr and mark the slot full.
358 static void idr_fill_slot(struct idr
*idr
, void *ptr
, int id
,
359 struct idr_layer
**pa
)
361 /* update hint used for lookup, cleared from free_layer() */
362 rcu_assign_pointer(idr
->hint
, pa
[0]);
364 rcu_assign_pointer(pa
[0]->ary
[id
& IDR_MASK
], (struct idr_layer
*)ptr
);
366 idr_mark_full(pa
, id
);
371 * idr_preload - preload for idr_alloc()
372 * @gfp_mask: allocation mask to use for preloading
374 * Preload per-cpu layer buffer for idr_alloc(). Can only be used from
375 * process context and each idr_preload() invocation should be matched with
376 * idr_preload_end(). Note that preemption is disabled while preloaded.
378 * The first idr_alloc() in the preloaded section can be treated as if it
379 * were invoked with @gfp_mask used for preloading. This allows using more
380 * permissive allocation masks for idrs protected by spinlocks.
382 * For example, if idr_alloc() below fails, the failure can be treated as
383 * if idr_alloc() were called with GFP_KERNEL rather than GFP_NOWAIT.
385 * idr_preload(GFP_KERNEL);
388 * id = idr_alloc(idr, ptr, start, end, GFP_NOWAIT);
395 void idr_preload(gfp_t gfp_mask
)
398 * Consuming preload buffer from non-process context breaks preload
399 * allocation guarantee. Disallow usage from those contexts.
401 WARN_ON_ONCE(in_interrupt());
402 might_sleep_if(gfpflags_allow_blocking(gfp_mask
));
407 * idr_alloc() is likely to succeed w/o full idr_layer buffer and
408 * return value from idr_alloc() needs to be checked for failure
409 * anyway. Silently give up if allocation fails. The caller can
410 * treat failures from idr_alloc() as if idr_alloc() were called
411 * with @gfp_mask which should be enough.
413 while (__this_cpu_read(idr_preload_cnt
) < MAX_IDR_FREE
) {
414 struct idr_layer
*new;
417 new = kmem_cache_zalloc(idr_layer_cache
, gfp_mask
);
422 /* link the new one to per-cpu preload list */
423 new->ary
[0] = __this_cpu_read(idr_preload_head
);
424 __this_cpu_write(idr_preload_head
, new);
425 __this_cpu_inc(idr_preload_cnt
);
428 EXPORT_SYMBOL(idr_preload
);
431 * idr_alloc - allocate new idr entry
432 * @idr: the (initialized) idr
433 * @ptr: pointer to be associated with the new id
434 * @start: the minimum id (inclusive)
435 * @end: the maximum id (exclusive, <= 0 for max)
436 * @gfp_mask: memory allocation flags
438 * Allocate an id in [start, end) and associate it with @ptr. If no ID is
439 * available in the specified range, returns -ENOSPC. On memory allocation
440 * failure, returns -ENOMEM.
442 * Note that @end is treated as max when <= 0. This is to always allow
443 * using @start + N as @end as long as N is inside integer range.
445 * The user is responsible for exclusively synchronizing all operations
446 * which may modify @idr. However, read-only accesses such as idr_find()
447 * or iteration can be performed under RCU read lock provided the user
448 * destroys @ptr in RCU-safe way after removal from idr.
450 int idr_alloc(struct idr
*idr
, void *ptr
, int start
, int end
, gfp_t gfp_mask
)
452 int max
= end
> 0 ? end
- 1 : INT_MAX
; /* inclusive upper limit */
453 struct idr_layer
*pa
[MAX_IDR_LEVEL
+ 1];
456 might_sleep_if(gfpflags_allow_blocking(gfp_mask
));
459 if (WARN_ON_ONCE(start
< 0))
461 if (unlikely(max
< start
))
465 id
= idr_get_empty_slot(idr
, start
, pa
, gfp_mask
, NULL
);
466 if (unlikely(id
< 0))
468 if (unlikely(id
> max
))
471 idr_fill_slot(idr
, ptr
, id
, pa
);
474 EXPORT_SYMBOL_GPL(idr_alloc
);
477 * idr_alloc_cyclic - allocate new idr entry in a cyclical fashion
478 * @idr: the (initialized) idr
479 * @ptr: pointer to be associated with the new id
480 * @start: the minimum id (inclusive)
481 * @end: the maximum id (exclusive, <= 0 for max)
482 * @gfp_mask: memory allocation flags
484 * Essentially the same as idr_alloc, but prefers to allocate progressively
485 * higher ids if it can. If the "cur" counter wraps, then it will start again
486 * at the "start" end of the range and allocate one that has already been used.
488 int idr_alloc_cyclic(struct idr
*idr
, void *ptr
, int start
, int end
,
493 id
= idr_alloc(idr
, ptr
, max(start
, idr
->cur
), end
, gfp_mask
);
495 id
= idr_alloc(idr
, ptr
, start
, end
, gfp_mask
);
501 EXPORT_SYMBOL(idr_alloc_cyclic
);
503 static void idr_remove_warning(int id
)
505 WARN(1, "idr_remove called for id=%d which is not allocated.\n", id
);
508 static void sub_remove(struct idr
*idp
, int shift
, int id
)
510 struct idr_layer
*p
= idp
->top
;
511 struct idr_layer
**pa
[MAX_IDR_LEVEL
+ 1];
512 struct idr_layer
***paa
= &pa
[0];
513 struct idr_layer
*to_free
;
519 while ((shift
> 0) && p
) {
520 n
= (id
>> shift
) & IDR_MASK
;
521 __clear_bit(n
, p
->bitmap
);
527 if (likely(p
!= NULL
&& test_bit(n
, p
->bitmap
))) {
528 __clear_bit(n
, p
->bitmap
);
529 RCU_INIT_POINTER(p
->ary
[n
], NULL
);
531 while(*paa
&& ! --((**paa
)->count
)){
533 free_layer(idp
, to_free
);
540 free_layer(idp
, to_free
);
542 idr_remove_warning(id
);
546 * idr_remove - remove the given id and free its slot
550 void idr_remove(struct idr
*idp
, int id
)
553 struct idr_layer
*to_free
;
558 if (id
> idr_max(idp
->layers
)) {
559 idr_remove_warning(id
);
563 sub_remove(idp
, (idp
->layers
- 1) * IDR_BITS
, id
);
564 if (idp
->top
&& idp
->top
->count
== 1 && (idp
->layers
> 1) &&
567 * Single child at leftmost slot: we can shrink the tree.
568 * This level is not needed anymore since when layers are
569 * inserted, they are inserted at the top of the existing
573 p
= idp
->top
->ary
[0];
574 rcu_assign_pointer(idp
->top
, p
);
577 bitmap_clear(to_free
->bitmap
, 0, IDR_SIZE
);
578 free_layer(idp
, to_free
);
581 EXPORT_SYMBOL(idr_remove
);
583 static void __idr_remove_all(struct idr
*idp
)
588 struct idr_layer
*pa
[MAX_IDR_LEVEL
+ 1];
589 struct idr_layer
**paa
= &pa
[0];
591 n
= idp
->layers
* IDR_BITS
;
593 RCU_INIT_POINTER(idp
->top
, NULL
);
594 max
= idr_max(idp
->layers
);
597 while (id
>= 0 && id
<= max
) {
599 while (n
> IDR_BITS
&& p
) {
601 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
)) {
610 free_layer(idp
, *paa
);
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 necessary, 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 *paa
= 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
]);
708 error
= fn(id
, (void *)p
, data
);
714 while (n
< fls(id
)) {
722 EXPORT_SYMBOL(idr_for_each
);
725 * idr_get_next - lookup next object of id to given id.
727 * @nextidp: pointer to lookup key
729 * Returns pointer to registered object with id, which is next number to
730 * given id. After being looked up, *@nextidp will be updated for the next
733 * This function can be called under rcu_read_lock(), given that the leaf
734 * pointers lifetimes are correctly managed.
736 void *idr_get_next(struct idr
*idp
, int *nextidp
)
738 struct idr_layer
*p
, *pa
[MAX_IDR_LEVEL
+ 1];
739 struct idr_layer
**paa
= &pa
[0];
744 p
= *paa
= rcu_dereference_raw(idp
->top
);
747 n
= (p
->layer
+ 1) * IDR_BITS
;
748 max
= idr_max(p
->layer
+ 1);
750 while (id
>= 0 && id
<= max
) {
754 p
= rcu_dereference_raw(p
->ary
[(id
>> n
) & IDR_MASK
]);
764 * Proceed to the next layer at the current level. Unlike
765 * idr_for_each(), @id isn't guaranteed to be aligned to
766 * layer boundary at this point and adding 1 << n may
767 * incorrectly skip IDs. Make sure we jump to the
768 * beginning of the next layer using round_up().
770 id
= round_up(id
+ 1, 1 << n
);
771 while (n
< fls(id
)) {
778 EXPORT_SYMBOL(idr_get_next
);
782 * idr_replace - replace pointer for given id
784 * @ptr: pointer you want associated with the id
787 * Replace the pointer registered with an id and return the old value.
788 * A %-ENOENT return indicates that @id was not found.
789 * A %-EINVAL return indicates that @id was not within valid constraints.
791 * The caller must serialize with writers.
793 void *idr_replace(struct idr
*idp
, void *ptr
, int id
)
796 struct idr_layer
*p
, *old_p
;
799 return ERR_PTR(-EINVAL
);
803 return ERR_PTR(-ENOENT
);
805 if (id
> idr_max(p
->layer
+ 1))
806 return ERR_PTR(-ENOENT
);
808 n
= p
->layer
* IDR_BITS
;
809 while ((n
> 0) && p
) {
810 p
= p
->ary
[(id
>> n
) & IDR_MASK
];
815 if (unlikely(p
== NULL
|| !test_bit(n
, p
->bitmap
)))
816 return ERR_PTR(-ENOENT
);
819 rcu_assign_pointer(p
->ary
[n
], ptr
);
823 EXPORT_SYMBOL(idr_replace
);
825 void __init
idr_init_cache(void)
827 idr_layer_cache
= kmem_cache_create("idr_layer_cache",
828 sizeof(struct idr_layer
), 0, SLAB_PANIC
, NULL
);
832 * idr_init - initialize idr handle
835 * This function is use to set up the handle (@idp) that you will pass
836 * to the rest of the functions.
838 void idr_init(struct idr
*idp
)
840 memset(idp
, 0, sizeof(struct idr
));
841 spin_lock_init(&idp
->lock
);
843 EXPORT_SYMBOL(idr_init
);
845 static int idr_has_entry(int id
, void *p
, void *data
)
850 bool idr_is_empty(struct idr
*idp
)
852 return !idr_for_each(idp
, idr_has_entry
, NULL
);
854 EXPORT_SYMBOL(idr_is_empty
);
857 * DOC: IDA description
858 * IDA - IDR based ID allocator
860 * This is id allocator without id -> pointer translation. Memory
861 * usage is much lower than full blown idr because each id only
862 * occupies a bit. ida uses a custom leaf node which contains
863 * IDA_BITMAP_BITS slots.
865 * 2007-04-25 written by Tejun Heo <htejun@gmail.com>
868 static void free_bitmap(struct ida
*ida
, struct ida_bitmap
*bitmap
)
872 if (!ida
->free_bitmap
) {
873 spin_lock_irqsave(&ida
->idr
.lock
, flags
);
874 if (!ida
->free_bitmap
) {
875 ida
->free_bitmap
= bitmap
;
878 spin_unlock_irqrestore(&ida
->idr
.lock
, flags
);
885 * ida_pre_get - reserve resources for ida allocation
887 * @gfp_mask: memory allocation flag
889 * This function should be called prior to locking and calling the
890 * following function. It preallocates enough memory to satisfy the
891 * worst possible allocation.
893 * If the system is REALLY out of memory this function returns %0,
896 int ida_pre_get(struct ida
*ida
, gfp_t gfp_mask
)
898 /* allocate idr_layers */
899 if (!__idr_pre_get(&ida
->idr
, gfp_mask
))
902 /* allocate free_bitmap */
903 if (!ida
->free_bitmap
) {
904 struct ida_bitmap
*bitmap
;
906 bitmap
= kmalloc(sizeof(struct ida_bitmap
), gfp_mask
);
910 free_bitmap(ida
, bitmap
);
915 EXPORT_SYMBOL(ida_pre_get
);
918 * ida_get_new_above - allocate new ID above or equal to a start id
920 * @starting_id: id to start search at
921 * @p_id: pointer to the allocated handle
923 * Allocate new ID above or equal to @starting_id. It should be called
924 * with any required locks.
926 * If memory is required, it will return %-EAGAIN, you should unlock
927 * and go back to the ida_pre_get() call. If the ida is full, it will
930 * @p_id returns a value in the range @starting_id ... %0x7fffffff.
932 int ida_get_new_above(struct ida
*ida
, int starting_id
, int *p_id
)
934 struct idr_layer
*pa
[MAX_IDR_LEVEL
+ 1];
935 struct ida_bitmap
*bitmap
;
937 int idr_id
= starting_id
/ IDA_BITMAP_BITS
;
938 int offset
= starting_id
% IDA_BITMAP_BITS
;
942 /* get vacant slot */
943 t
= idr_get_empty_slot(&ida
->idr
, idr_id
, pa
, 0, &ida
->idr
);
945 return t
== -ENOMEM
? -EAGAIN
: t
;
947 if (t
* IDA_BITMAP_BITS
>= MAX_IDR_BIT
)
954 /* if bitmap isn't there, create a new one */
955 bitmap
= (void *)pa
[0]->ary
[idr_id
& IDR_MASK
];
957 spin_lock_irqsave(&ida
->idr
.lock
, flags
);
958 bitmap
= ida
->free_bitmap
;
959 ida
->free_bitmap
= NULL
;
960 spin_unlock_irqrestore(&ida
->idr
.lock
, flags
);
965 memset(bitmap
, 0, sizeof(struct ida_bitmap
));
966 rcu_assign_pointer(pa
[0]->ary
[idr_id
& IDR_MASK
],
971 /* lookup for empty slot */
972 t
= find_next_zero_bit(bitmap
->bitmap
, IDA_BITMAP_BITS
, offset
);
973 if (t
== IDA_BITMAP_BITS
) {
974 /* no empty slot after offset, continue to the next chunk */
980 id
= idr_id
* IDA_BITMAP_BITS
+ t
;
981 if (id
>= MAX_IDR_BIT
)
984 __set_bit(t
, bitmap
->bitmap
);
985 if (++bitmap
->nr_busy
== IDA_BITMAP_BITS
)
986 idr_mark_full(pa
, idr_id
);
990 /* Each leaf node can handle nearly a thousand slots and the
991 * whole idea of ida is to have small memory foot print.
992 * Throw away extra resources one by one after each successful
995 if (ida
->idr
.id_free_cnt
|| ida
->free_bitmap
) {
996 struct idr_layer
*p
= get_from_free_list(&ida
->idr
);
998 kmem_cache_free(idr_layer_cache
, p
);
1003 EXPORT_SYMBOL(ida_get_new_above
);
1006 * ida_remove - remove the given ID
1010 void ida_remove(struct ida
*ida
, int id
)
1012 struct idr_layer
*p
= ida
->idr
.top
;
1013 int shift
= (ida
->idr
.layers
- 1) * IDR_BITS
;
1014 int idr_id
= id
/ IDA_BITMAP_BITS
;
1015 int offset
= id
% IDA_BITMAP_BITS
;
1017 struct ida_bitmap
*bitmap
;
1019 if (idr_id
> idr_max(ida
->idr
.layers
))
1022 /* clear full bits while looking up the leaf idr_layer */
1023 while ((shift
> 0) && p
) {
1024 n
= (idr_id
>> shift
) & IDR_MASK
;
1025 __clear_bit(n
, p
->bitmap
);
1033 n
= idr_id
& IDR_MASK
;
1034 __clear_bit(n
, p
->bitmap
);
1036 bitmap
= (void *)p
->ary
[n
];
1037 if (!bitmap
|| !test_bit(offset
, bitmap
->bitmap
))
1040 /* update bitmap and remove it if empty */
1041 __clear_bit(offset
, bitmap
->bitmap
);
1042 if (--bitmap
->nr_busy
== 0) {
1043 __set_bit(n
, p
->bitmap
); /* to please idr_remove() */
1044 idr_remove(&ida
->idr
, idr_id
);
1045 free_bitmap(ida
, bitmap
);
1051 WARN(1, "ida_remove called for id=%d which is not allocated.\n", id
);
1053 EXPORT_SYMBOL(ida_remove
);
1056 * ida_destroy - release all cached layers within an ida tree
1059 void ida_destroy(struct ida
*ida
)
1061 idr_destroy(&ida
->idr
);
1062 kfree(ida
->free_bitmap
);
1064 EXPORT_SYMBOL(ida_destroy
);
1067 * ida_simple_get - get a new id.
1068 * @ida: the (initialized) ida.
1069 * @start: the minimum id (inclusive, < 0x8000000)
1070 * @end: the maximum id (exclusive, < 0x8000000 or 0)
1071 * @gfp_mask: memory allocation flags
1073 * Allocates an id in the range start <= id < end, or returns -ENOSPC.
1074 * On memory allocation failure, returns -ENOMEM.
1076 * Use ida_simple_remove() to get rid of an id.
1078 int ida_simple_get(struct ida
*ida
, unsigned int start
, unsigned int end
,
1083 unsigned long flags
;
1085 BUG_ON((int)start
< 0);
1086 BUG_ON((int)end
< 0);
1091 BUG_ON(end
< start
);
1096 if (!ida_pre_get(ida
, gfp_mask
))
1099 spin_lock_irqsave(&simple_ida_lock
, flags
);
1100 ret
= ida_get_new_above(ida
, start
, &id
);
1103 ida_remove(ida
, id
);
1109 spin_unlock_irqrestore(&simple_ida_lock
, flags
);
1111 if (unlikely(ret
== -EAGAIN
))
1116 EXPORT_SYMBOL(ida_simple_get
);
1119 * ida_simple_remove - remove an allocated id.
1120 * @ida: the (initialized) ida.
1121 * @id: the id returned by ida_simple_get.
1123 void ida_simple_remove(struct ida
*ida
, unsigned int id
)
1125 unsigned long flags
;
1127 BUG_ON((int)id
< 0);
1128 spin_lock_irqsave(&simple_ida_lock
, flags
);
1129 ida_remove(ida
, id
);
1130 spin_unlock_irqrestore(&simple_ida_lock
, flags
);
1132 EXPORT_SYMBOL(ida_simple_remove
);
1135 * ida_init - initialize ida handle
1138 * This function is use to set up the handle (@ida) that you will pass
1139 * to the rest of the functions.
1141 void ida_init(struct ida
*ida
)
1143 memset(ida
, 0, sizeof(struct ida
));
1144 idr_init(&ida
->idr
);
1147 EXPORT_SYMBOL(ida_init
);