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git.proxmox.com Git - mirror_ubuntu-jammy-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.
22 * You can release ids at any time. When all ids are released, most of
23 * the memory is returned (we keep IDR_FREE_MAX) in a local pool so we
24 * don't need to go to the memory "store" during an id allocate, just
25 * so you don't need to be too concerned about locking and conflicts
26 * with the slab allocator.
29 #ifndef TEST // to test in user space...
30 #include <linux/slab.h>
31 #include <linux/init.h>
32 #include <linux/module.h>
34 #include <linux/err.h>
35 #include <linux/string.h>
36 #include <linux/idr.h>
38 static struct kmem_cache
*idr_layer_cache
;
40 static struct idr_layer
*get_from_free_list(struct idr
*idp
)
45 spin_lock_irqsave(&idp
->lock
, flags
);
46 if ((p
= idp
->id_free
)) {
47 idp
->id_free
= p
->ary
[0];
51 spin_unlock_irqrestore(&idp
->lock
, flags
);
55 static void idr_layer_rcu_free(struct rcu_head
*head
)
57 struct idr_layer
*layer
;
59 layer
= container_of(head
, struct idr_layer
, rcu_head
);
60 kmem_cache_free(idr_layer_cache
, layer
);
63 static inline void free_layer(struct idr_layer
*p
)
65 call_rcu(&p
->rcu_head
, idr_layer_rcu_free
);
68 /* only called when idp->lock is held */
69 static void __move_to_free_list(struct idr
*idp
, struct idr_layer
*p
)
71 p
->ary
[0] = idp
->id_free
;
76 static void move_to_free_list(struct idr
*idp
, struct idr_layer
*p
)
81 * Depends on the return element being zeroed.
83 spin_lock_irqsave(&idp
->lock
, flags
);
84 __move_to_free_list(idp
, p
);
85 spin_unlock_irqrestore(&idp
->lock
, flags
);
88 static void idr_mark_full(struct idr_layer
**pa
, int id
)
90 struct idr_layer
*p
= pa
[0];
93 __set_bit(id
& IDR_MASK
, &p
->bitmap
);
95 * If this layer is full mark the bit in the layer above to
96 * show that this part of the radix tree is full. This may
97 * complete the layer above and require walking up the radix
100 while (p
->bitmap
== IDR_FULL
) {
104 __set_bit((id
& IDR_MASK
), &p
->bitmap
);
109 * idr_pre_get - reserve resources for idr allocation
111 * @gfp_mask: memory allocation flags
113 * This function should be called prior to calling the idr_get_new* functions.
114 * It preallocates enough memory to satisfy the worst possible allocation. The
115 * caller should pass in GFP_KERNEL if possible. This of course requires that
116 * no spinning locks be held.
118 * If the system is REALLY out of memory this function returns %0,
121 int idr_pre_get(struct idr
*idp
, gfp_t gfp_mask
)
123 while (idp
->id_free_cnt
< IDR_FREE_MAX
) {
124 struct idr_layer
*new;
125 new = kmem_cache_zalloc(idr_layer_cache
, gfp_mask
);
128 move_to_free_list(idp
, new);
132 EXPORT_SYMBOL(idr_pre_get
);
134 static int sub_alloc(struct idr
*idp
, int *starting_id
, struct idr_layer
**pa
)
137 struct idr_layer
*p
, *new;
148 * We run around this while until we reach the leaf node...
150 n
= (id
>> (IDR_BITS
*l
)) & IDR_MASK
;
152 m
= find_next_bit(&bm
, IDR_SIZE
, n
);
154 /* no space available go back to previous layer. */
157 id
= (id
| ((1 << (IDR_BITS
* l
)) - 1)) + 1;
159 /* if already at the top layer, we need to grow */
160 if (id
>= 1 << (idp
->layers
* IDR_BITS
)) {
162 return IDR_NEED_TO_GROW
;
167 /* If we need to go up one layer, continue the
168 * loop; otherwise, restart from the top.
170 sh
= IDR_BITS
* (l
+ 1);
171 if (oid
>> sh
== id
>> sh
)
178 id
= ((id
>> sh
) ^ n
^ m
) << sh
;
180 if ((id
>= MAX_ID_BIT
) || (id
< 0))
181 return IDR_NOMORE_SPACE
;
185 * Create the layer below if it is missing.
188 new = get_from_free_list(idp
);
192 rcu_assign_pointer(p
->ary
[m
], new);
203 static int idr_get_empty_slot(struct idr
*idp
, int starting_id
,
204 struct idr_layer
**pa
)
206 struct idr_layer
*p
, *new;
213 layers
= idp
->layers
;
215 if (!(p
= get_from_free_list(idp
)))
221 * Add a new layer to the top of the tree if the requested
222 * id is larger than the currently allocated space.
224 while ((layers
< (MAX_LEVEL
- 1)) && (id
>= (1 << (layers
*IDR_BITS
)))) {
227 /* special case: if the tree is currently empty,
228 * then we grow the tree by moving the top node
234 if (!(new = get_from_free_list(idp
))) {
236 * The allocation failed. If we built part of
237 * the structure tear it down.
239 spin_lock_irqsave(&idp
->lock
, flags
);
240 for (new = p
; p
&& p
!= idp
->top
; new = p
) {
243 new->bitmap
= new->count
= 0;
244 __move_to_free_list(idp
, new);
246 spin_unlock_irqrestore(&idp
->lock
, flags
);
251 new->layer
= layers
-1;
252 if (p
->bitmap
== IDR_FULL
)
253 __set_bit(0, &new->bitmap
);
256 rcu_assign_pointer(idp
->top
, p
);
257 idp
->layers
= layers
;
258 v
= sub_alloc(idp
, &id
, pa
);
259 if (v
== IDR_NEED_TO_GROW
)
264 static int idr_get_new_above_int(struct idr
*idp
, void *ptr
, int starting_id
)
266 struct idr_layer
*pa
[MAX_LEVEL
];
269 id
= idr_get_empty_slot(idp
, starting_id
, pa
);
272 * Successfully found an empty slot. Install the user
273 * pointer and mark the slot full.
275 rcu_assign_pointer(pa
[0]->ary
[id
& IDR_MASK
],
276 (struct idr_layer
*)ptr
);
278 idr_mark_full(pa
, id
);
285 * idr_get_new_above - allocate new idr entry above or equal to a start id
287 * @ptr: pointer you want associated with the id
288 * @starting_id: id to start search at
289 * @id: pointer to the allocated handle
291 * This is the allocate id function. It should be called with any
294 * If allocation from IDR's private freelist fails, idr_get_new_above() will
295 * return %-EAGAIN. The caller should retry the idr_pre_get() call to refill
296 * IDR's preallocation and then retry the idr_get_new_above() call.
298 * If the idr is full idr_get_new_above() will return %-ENOSPC.
300 * @id returns a value in the range @starting_id ... %0x7fffffff
302 int idr_get_new_above(struct idr
*idp
, void *ptr
, int starting_id
, int *id
)
306 rv
= idr_get_new_above_int(idp
, ptr
, starting_id
);
308 * This is a cheap hack until the IDR code can be fixed to
309 * return proper error values.
312 return _idr_rc_to_errno(rv
);
316 EXPORT_SYMBOL(idr_get_new_above
);
319 * idr_get_new - allocate new idr entry
321 * @ptr: pointer you want associated with the id
322 * @id: pointer to the allocated handle
324 * If allocation from IDR's private freelist fails, idr_get_new_above() will
325 * return %-EAGAIN. The caller should retry the idr_pre_get() call to refill
326 * IDR's preallocation and then retry the idr_get_new_above() call.
328 * If the idr is full idr_get_new_above() will return %-ENOSPC.
330 * @id returns a value in the range %0 ... %0x7fffffff
332 int idr_get_new(struct idr
*idp
, void *ptr
, int *id
)
336 rv
= idr_get_new_above_int(idp
, ptr
, 0);
338 * This is a cheap hack until the IDR code can be fixed to
339 * return proper error values.
342 return _idr_rc_to_errno(rv
);
346 EXPORT_SYMBOL(idr_get_new
);
348 static void idr_remove_warning(int id
)
351 "idr_remove called for id=%d which is not allocated.\n", id
);
355 static void sub_remove(struct idr
*idp
, int shift
, int id
)
357 struct idr_layer
*p
= idp
->top
;
358 struct idr_layer
**pa
[MAX_LEVEL
];
359 struct idr_layer
***paa
= &pa
[0];
360 struct idr_layer
*to_free
;
366 while ((shift
> 0) && p
) {
367 n
= (id
>> shift
) & IDR_MASK
;
368 __clear_bit(n
, &p
->bitmap
);
374 if (likely(p
!= NULL
&& test_bit(n
, &p
->bitmap
))){
375 __clear_bit(n
, &p
->bitmap
);
376 rcu_assign_pointer(p
->ary
[n
], NULL
);
378 while(*paa
&& ! --((**paa
)->count
)){
389 idr_remove_warning(id
);
393 * idr_remove - remove the given id and free its slot
397 void idr_remove(struct idr
*idp
, int id
)
400 struct idr_layer
*to_free
;
402 /* Mask off upper bits we don't use for the search. */
405 sub_remove(idp
, (idp
->layers
- 1) * IDR_BITS
, id
);
406 if (idp
->top
&& idp
->top
->count
== 1 && (idp
->layers
> 1) &&
409 * Single child at leftmost slot: we can shrink the tree.
410 * This level is not needed anymore since when layers are
411 * inserted, they are inserted at the top of the existing
415 p
= idp
->top
->ary
[0];
416 rcu_assign_pointer(idp
->top
, p
);
418 to_free
->bitmap
= to_free
->count
= 0;
421 while (idp
->id_free_cnt
>= IDR_FREE_MAX
) {
422 p
= get_from_free_list(idp
);
424 * Note: we don't call the rcu callback here, since the only
425 * layers that fall into the freelist are those that have been
428 kmem_cache_free(idr_layer_cache
, p
);
432 EXPORT_SYMBOL(idr_remove
);
435 * idr_remove_all - remove all ids from the given idr tree
438 * idr_destroy() only frees up unused, cached idp_layers, but this
439 * function will remove all id mappings and leave all idp_layers
442 * A typical clean-up sequence for objects stored in an idr tree will
443 * use idr_for_each() to free all objects, if necessay, then
444 * idr_remove_all() to remove all ids, and idr_destroy() to free
445 * up the cached idr_layers.
447 void idr_remove_all(struct idr
*idp
)
452 struct idr_layer
*pa
[MAX_LEVEL
];
453 struct idr_layer
**paa
= &pa
[0];
455 n
= idp
->layers
* IDR_BITS
;
457 rcu_assign_pointer(idp
->top
, NULL
);
462 while (n
> IDR_BITS
&& p
) {
465 p
= p
->ary
[(id
>> n
) & IDR_MASK
];
470 /* Get the highest bit that the above add changed from 0->1. */
471 while (n
< fls(id
^ bt_mask
)) {
480 EXPORT_SYMBOL(idr_remove_all
);
483 * idr_destroy - release all cached layers within an idr tree
486 void idr_destroy(struct idr
*idp
)
488 while (idp
->id_free_cnt
) {
489 struct idr_layer
*p
= get_from_free_list(idp
);
490 kmem_cache_free(idr_layer_cache
, p
);
493 EXPORT_SYMBOL(idr_destroy
);
496 * idr_find - return pointer for given id
500 * Return the pointer given the id it has been registered with. A %NULL
501 * return indicates that @id is not valid or you passed %NULL in
504 * This function can be called under rcu_read_lock(), given that the leaf
505 * pointers lifetimes are correctly managed.
507 void *idr_find(struct idr
*idp
, int id
)
512 p
= rcu_dereference_raw(idp
->top
);
515 n
= (p
->layer
+1) * IDR_BITS
;
517 /* Mask off upper bits we don't use for the search. */
526 BUG_ON(n
!= p
->layer
*IDR_BITS
);
527 p
= rcu_dereference_raw(p
->ary
[(id
>> n
) & IDR_MASK
]);
531 EXPORT_SYMBOL(idr_find
);
534 * idr_for_each - iterate through all stored pointers
536 * @fn: function to be called for each pointer
537 * @data: data passed back to callback function
539 * Iterate over the pointers registered with the given idr. The
540 * callback function will be called for each pointer currently
541 * registered, passing the id, the pointer and the data pointer passed
542 * to this function. It is not safe to modify the idr tree while in
543 * the callback, so functions such as idr_get_new and idr_remove are
546 * We check the return of @fn each time. If it returns anything other
547 * than %0, we break out and return that value.
549 * The caller must serialize idr_for_each() vs idr_get_new() and idr_remove().
551 int idr_for_each(struct idr
*idp
,
552 int (*fn
)(int id
, void *p
, void *data
), void *data
)
554 int n
, id
, max
, error
= 0;
556 struct idr_layer
*pa
[MAX_LEVEL
];
557 struct idr_layer
**paa
= &pa
[0];
559 n
= idp
->layers
* IDR_BITS
;
560 p
= rcu_dereference_raw(idp
->top
);
568 p
= rcu_dereference_raw(p
->ary
[(id
>> n
) & IDR_MASK
]);
572 error
= fn(id
, (void *)p
, data
);
578 while (n
< fls(id
)) {
586 EXPORT_SYMBOL(idr_for_each
);
589 * idr_get_next - lookup next object of id to given id.
591 * @nextidp: pointer to lookup key
593 * Returns pointer to registered object with id, which is next number to
594 * given id. After being looked up, *@nextidp will be updated for the next
598 void *idr_get_next(struct idr
*idp
, int *nextidp
)
600 struct idr_layer
*p
, *pa
[MAX_LEVEL
];
601 struct idr_layer
**paa
= &pa
[0];
606 n
= idp
->layers
* IDR_BITS
;
608 p
= rcu_dereference_raw(idp
->top
);
616 p
= rcu_dereference_raw(p
->ary
[(id
>> n
) & IDR_MASK
]);
625 while (n
< fls(id
)) {
632 EXPORT_SYMBOL(idr_get_next
);
636 * idr_replace - replace pointer for given id
638 * @ptr: pointer you want associated with the id
641 * Replace the pointer registered with an id and return the old value.
642 * A %-ENOENT return indicates that @id was not found.
643 * A %-EINVAL return indicates that @id was not within valid constraints.
645 * The caller must serialize with writers.
647 void *idr_replace(struct idr
*idp
, void *ptr
, int id
)
650 struct idr_layer
*p
, *old_p
;
654 return ERR_PTR(-EINVAL
);
656 n
= (p
->layer
+1) * IDR_BITS
;
661 return ERR_PTR(-EINVAL
);
664 while ((n
> 0) && p
) {
665 p
= p
->ary
[(id
>> n
) & IDR_MASK
];
670 if (unlikely(p
== NULL
|| !test_bit(n
, &p
->bitmap
)))
671 return ERR_PTR(-ENOENT
);
674 rcu_assign_pointer(p
->ary
[n
], ptr
);
678 EXPORT_SYMBOL(idr_replace
);
680 void __init
idr_init_cache(void)
682 idr_layer_cache
= kmem_cache_create("idr_layer_cache",
683 sizeof(struct idr_layer
), 0, SLAB_PANIC
, NULL
);
687 * idr_init - initialize idr handle
690 * This function is use to set up the handle (@idp) that you will pass
691 * to the rest of the functions.
693 void idr_init(struct idr
*idp
)
695 memset(idp
, 0, sizeof(struct idr
));
696 spin_lock_init(&idp
->lock
);
698 EXPORT_SYMBOL(idr_init
);
702 * DOC: IDA description
703 * IDA - IDR based ID allocator
705 * This is id allocator without id -> pointer translation. Memory
706 * usage is much lower than full blown idr because each id only
707 * occupies a bit. ida uses a custom leaf node which contains
708 * IDA_BITMAP_BITS slots.
710 * 2007-04-25 written by Tejun Heo <htejun@gmail.com>
713 static void free_bitmap(struct ida
*ida
, struct ida_bitmap
*bitmap
)
717 if (!ida
->free_bitmap
) {
718 spin_lock_irqsave(&ida
->idr
.lock
, flags
);
719 if (!ida
->free_bitmap
) {
720 ida
->free_bitmap
= bitmap
;
723 spin_unlock_irqrestore(&ida
->idr
.lock
, flags
);
730 * ida_pre_get - reserve resources for ida allocation
732 * @gfp_mask: memory allocation flag
734 * This function should be called prior to locking and calling the
735 * following function. It preallocates enough memory to satisfy the
736 * worst possible allocation.
738 * If the system is REALLY out of memory this function returns %0,
741 int ida_pre_get(struct ida
*ida
, gfp_t gfp_mask
)
743 /* allocate idr_layers */
744 if (!idr_pre_get(&ida
->idr
, gfp_mask
))
747 /* allocate free_bitmap */
748 if (!ida
->free_bitmap
) {
749 struct ida_bitmap
*bitmap
;
751 bitmap
= kmalloc(sizeof(struct ida_bitmap
), gfp_mask
);
755 free_bitmap(ida
, bitmap
);
760 EXPORT_SYMBOL(ida_pre_get
);
763 * ida_get_new_above - allocate new ID above or equal to a start id
765 * @starting_id: id to start search at
766 * @p_id: pointer to the allocated handle
768 * Allocate new ID above or equal to @ida. It should be called with
769 * any required locks.
771 * If memory is required, it will return %-EAGAIN, you should unlock
772 * and go back to the ida_pre_get() call. If the ida is full, it will
775 * @p_id returns a value in the range @starting_id ... %0x7fffffff.
777 int ida_get_new_above(struct ida
*ida
, int starting_id
, int *p_id
)
779 struct idr_layer
*pa
[MAX_LEVEL
];
780 struct ida_bitmap
*bitmap
;
782 int idr_id
= starting_id
/ IDA_BITMAP_BITS
;
783 int offset
= starting_id
% IDA_BITMAP_BITS
;
787 /* get vacant slot */
788 t
= idr_get_empty_slot(&ida
->idr
, idr_id
, pa
);
790 return _idr_rc_to_errno(t
);
792 if (t
* IDA_BITMAP_BITS
>= MAX_ID_BIT
)
799 /* if bitmap isn't there, create a new one */
800 bitmap
= (void *)pa
[0]->ary
[idr_id
& IDR_MASK
];
802 spin_lock_irqsave(&ida
->idr
.lock
, flags
);
803 bitmap
= ida
->free_bitmap
;
804 ida
->free_bitmap
= NULL
;
805 spin_unlock_irqrestore(&ida
->idr
.lock
, flags
);
810 memset(bitmap
, 0, sizeof(struct ida_bitmap
));
811 rcu_assign_pointer(pa
[0]->ary
[idr_id
& IDR_MASK
],
816 /* lookup for empty slot */
817 t
= find_next_zero_bit(bitmap
->bitmap
, IDA_BITMAP_BITS
, offset
);
818 if (t
== IDA_BITMAP_BITS
) {
819 /* no empty slot after offset, continue to the next chunk */
825 id
= idr_id
* IDA_BITMAP_BITS
+ t
;
826 if (id
>= MAX_ID_BIT
)
829 __set_bit(t
, bitmap
->bitmap
);
830 if (++bitmap
->nr_busy
== IDA_BITMAP_BITS
)
831 idr_mark_full(pa
, idr_id
);
835 /* Each leaf node can handle nearly a thousand slots and the
836 * whole idea of ida is to have small memory foot print.
837 * Throw away extra resources one by one after each successful
840 if (ida
->idr
.id_free_cnt
|| ida
->free_bitmap
) {
841 struct idr_layer
*p
= get_from_free_list(&ida
->idr
);
843 kmem_cache_free(idr_layer_cache
, p
);
848 EXPORT_SYMBOL(ida_get_new_above
);
851 * ida_get_new - allocate new ID
853 * @p_id: pointer to the allocated handle
855 * Allocate new ID. It should be called with any required locks.
857 * If memory is required, it will return %-EAGAIN, you should unlock
858 * and go back to the idr_pre_get() call. If the idr is full, it will
861 * @id returns a value in the range %0 ... %0x7fffffff.
863 int ida_get_new(struct ida
*ida
, int *p_id
)
865 return ida_get_new_above(ida
, 0, p_id
);
867 EXPORT_SYMBOL(ida_get_new
);
870 * ida_remove - remove the given ID
874 void ida_remove(struct ida
*ida
, int id
)
876 struct idr_layer
*p
= ida
->idr
.top
;
877 int shift
= (ida
->idr
.layers
- 1) * IDR_BITS
;
878 int idr_id
= id
/ IDA_BITMAP_BITS
;
879 int offset
= id
% IDA_BITMAP_BITS
;
881 struct ida_bitmap
*bitmap
;
883 /* clear full bits while looking up the leaf idr_layer */
884 while ((shift
> 0) && p
) {
885 n
= (idr_id
>> shift
) & IDR_MASK
;
886 __clear_bit(n
, &p
->bitmap
);
894 n
= idr_id
& IDR_MASK
;
895 __clear_bit(n
, &p
->bitmap
);
897 bitmap
= (void *)p
->ary
[n
];
898 if (!test_bit(offset
, bitmap
->bitmap
))
901 /* update bitmap and remove it if empty */
902 __clear_bit(offset
, bitmap
->bitmap
);
903 if (--bitmap
->nr_busy
== 0) {
904 __set_bit(n
, &p
->bitmap
); /* to please idr_remove() */
905 idr_remove(&ida
->idr
, idr_id
);
906 free_bitmap(ida
, bitmap
);
913 "ida_remove called for id=%d which is not allocated.\n", id
);
915 EXPORT_SYMBOL(ida_remove
);
918 * ida_destroy - release all cached layers within an ida tree
921 void ida_destroy(struct ida
*ida
)
923 idr_destroy(&ida
->idr
);
924 kfree(ida
->free_bitmap
);
926 EXPORT_SYMBOL(ida_destroy
);
929 * ida_init - initialize ida handle
932 * This function is use to set up the handle (@ida) that you will pass
933 * to the rest of the functions.
935 void ida_init(struct ida
*ida
)
937 memset(ida
, 0, sizeof(struct ida
));
941 EXPORT_SYMBOL(ida_init
);