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 MAX_IDR_FREE) 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/export.h>
34 #include <linux/err.h>
35 #include <linux/string.h>
36 #include <linux/idr.h>
37 #include <linux/spinlock.h>
38 #include <linux/percpu.h>
39 #include <linux/hardirq.h>
41 #define MAX_IDR_SHIFT (sizeof(int) * 8 - 1)
42 #define MAX_IDR_BIT (1U << MAX_IDR_SHIFT)
44 /* Leave the possibility of an incomplete final layer */
45 #define MAX_IDR_LEVEL ((MAX_IDR_SHIFT + IDR_BITS - 1) / IDR_BITS)
47 /* Number of id_layer structs to leave in free list */
48 #define MAX_IDR_FREE (MAX_IDR_LEVEL * 2)
50 static struct kmem_cache *idr_layer_cache;
51 static DEFINE_PER_CPU(struct idr_layer *, idr_preload_head);
52 static DEFINE_PER_CPU(int, idr_preload_cnt);
53 static DEFINE_SPINLOCK(simple_ida_lock);
55 /* the maximum ID which can be allocated given idr->layers */
56 static int idr_max(int layers)
58 int bits = min_t(int, layers * IDR_BITS, MAX_IDR_SHIFT);
60 return (1 << bits) - 1;
64 * Prefix mask for an idr_layer at @layer. For layer 0, the prefix mask is
65 * all bits except for the lower IDR_BITS. For layer 1, 2 * IDR_BITS, and
68 static int idr_layer_prefix_mask(int layer)
70 return ~idr_max(layer + 1);
73 static struct idr_layer *get_from_free_list(struct idr *idp)
78 spin_lock_irqsave(&idp->lock, flags);
79 if ((p = idp->id_free)) {
80 idp->id_free = p->ary[0];
84 spin_unlock_irqrestore(&idp->lock, flags);
89 * idr_layer_alloc - allocate a new idr_layer
90 * @gfp_mask: allocation mask
91 * @layer_idr: optional idr to allocate from
93 * If @layer_idr is %NULL, directly allocate one using @gfp_mask or fetch
94 * one from the per-cpu preload buffer. If @layer_idr is not %NULL, fetch
95 * an idr_layer from @idr->id_free.
97 * @layer_idr is to maintain backward compatibility with the old alloc
98 * interface - idr_pre_get() and idr_get_new*() - and will be removed
99 * together with per-pool preload buffer.
101 static struct idr_layer *idr_layer_alloc(gfp_t gfp_mask, struct idr *layer_idr)
103 struct idr_layer *new;
105 /* this is the old path, bypass to get_from_free_list() */
107 return get_from_free_list(layer_idr);
109 /* try to allocate directly from kmem_cache */
110 new = kmem_cache_zalloc(idr_layer_cache, gfp_mask);
115 * Try to fetch one from the per-cpu preload buffer if in process
116 * context. See idr_preload() for details.
122 new = __this_cpu_read(idr_preload_head);
124 __this_cpu_write(idr_preload_head, new->ary[0]);
125 __this_cpu_dec(idr_preload_cnt);
132 static void idr_layer_rcu_free(struct rcu_head *head)
134 struct idr_layer *layer;
136 layer = container_of(head, struct idr_layer, rcu_head);
137 kmem_cache_free(idr_layer_cache, layer);
140 static inline void free_layer(struct idr_layer *p)
142 call_rcu(&p->rcu_head, idr_layer_rcu_free);
145 /* only called when idp->lock is held */
146 static void __move_to_free_list(struct idr *idp, struct idr_layer *p)
148 p->ary[0] = idp->id_free;
153 static void move_to_free_list(struct idr *idp, struct idr_layer *p)
158 * Depends on the return element being zeroed.
160 spin_lock_irqsave(&idp->lock, flags);
161 __move_to_free_list(idp, p);
162 spin_unlock_irqrestore(&idp->lock, flags);
165 static void idr_mark_full(struct idr_layer **pa, int id)
167 struct idr_layer *p = pa[0];
170 __set_bit(id & IDR_MASK, p->bitmap);
172 * If this layer is full mark the bit in the layer above to
173 * show that this part of the radix tree is full. This may
174 * complete the layer above and require walking up the radix
177 while (bitmap_full(p->bitmap, IDR_SIZE)) {
181 __set_bit((id & IDR_MASK), p->bitmap);
186 * idr_pre_get - reserve resources for idr allocation
188 * @gfp_mask: memory allocation flags
190 * This function should be called prior to calling the idr_get_new* functions.
191 * It preallocates enough memory to satisfy the worst possible allocation. The
192 * caller should pass in GFP_KERNEL if possible. This of course requires that
193 * no spinning locks be held.
195 * If the system is REALLY out of memory this function returns %0,
198 int idr_pre_get(struct idr *idp, gfp_t gfp_mask)
200 while (idp->id_free_cnt < MAX_IDR_FREE) {
201 struct idr_layer *new;
202 new = kmem_cache_zalloc(idr_layer_cache, gfp_mask);
205 move_to_free_list(idp, new);
209 EXPORT_SYMBOL(idr_pre_get);
212 * sub_alloc - try to allocate an id without growing the tree depth
214 * @starting_id: id to start search at
215 * @id: pointer to the allocated handle
216 * @pa: idr_layer[MAX_IDR_LEVEL] used as backtrack buffer
217 * @gfp_mask: allocation mask for idr_layer_alloc()
218 * @layer_idr: optional idr passed to idr_layer_alloc()
220 * Allocate an id in range [@starting_id, INT_MAX] from @idp without
221 * growing its depth. Returns
223 * the allocated id >= 0 if successful,
224 * -EAGAIN if the tree needs to grow for allocation to succeed,
225 * -ENOSPC if the id space is exhausted,
226 * -ENOMEM if more idr_layers need to be allocated.
228 static int sub_alloc(struct idr *idp, int *starting_id, struct idr_layer **pa,
229 gfp_t gfp_mask, struct idr *layer_idr)
232 struct idr_layer *p, *new;
242 * We run around this while until we reach the leaf node...
244 n = (id >> (IDR_BITS*l)) & IDR_MASK;
245 m = find_next_zero_bit(p->bitmap, IDR_SIZE, n);
247 /* no space available go back to previous layer. */
250 id = (id | ((1 << (IDR_BITS * l)) - 1)) + 1;
252 /* if already at the top layer, we need to grow */
253 if (id >= 1 << (idp->layers * IDR_BITS)) {
260 /* If we need to go up one layer, continue the
261 * loop; otherwise, restart from the top.
263 sh = IDR_BITS * (l + 1);
264 if (oid >> sh == id >> sh)
271 id = ((id >> sh) ^ n ^ m) << sh;
273 if ((id >= MAX_IDR_BIT) || (id < 0))
278 * Create the layer below if it is missing.
281 new = idr_layer_alloc(gfp_mask, layer_idr);
285 new->prefix = id & idr_layer_prefix_mask(new->layer);
286 rcu_assign_pointer(p->ary[m], new);
297 static int idr_get_empty_slot(struct idr *idp, int starting_id,
298 struct idr_layer **pa, gfp_t gfp_mask,
299 struct idr *layer_idr)
301 struct idr_layer *p, *new;
308 layers = idp->layers;
310 if (!(p = idr_layer_alloc(gfp_mask, layer_idr)))
316 * Add a new layer to the top of the tree if the requested
317 * id is larger than the currently allocated space.
319 while (id > idr_max(layers)) {
322 /* special case: if the tree is currently empty,
323 * then we grow the tree by moving the top node
327 WARN_ON_ONCE(p->prefix);
330 if (!(new = idr_layer_alloc(gfp_mask, layer_idr))) {
332 * The allocation failed. If we built part of
333 * the structure tear it down.
335 spin_lock_irqsave(&idp->lock, flags);
336 for (new = p; p && p != idp->top; new = p) {
340 bitmap_clear(new->bitmap, 0, IDR_SIZE);
341 __move_to_free_list(idp, new);
343 spin_unlock_irqrestore(&idp->lock, flags);
348 new->layer = layers-1;
349 new->prefix = id & idr_layer_prefix_mask(new->layer);
350 if (bitmap_full(p->bitmap, IDR_SIZE))
351 __set_bit(0, new->bitmap);
354 rcu_assign_pointer(idp->top, p);
355 idp->layers = layers;
356 v = sub_alloc(idp, &id, pa, gfp_mask, layer_idr);
363 * @id and @pa are from a successful allocation from idr_get_empty_slot().
364 * Install the user pointer @ptr and mark the slot full.
366 static void idr_fill_slot(void *ptr, int id, struct idr_layer **pa)
368 rcu_assign_pointer(pa[0]->ary[id & IDR_MASK], (struct idr_layer *)ptr);
370 idr_mark_full(pa, id);
374 * idr_get_new_above - allocate new idr entry above or equal to a start id
376 * @ptr: pointer you want associated with the id
377 * @starting_id: id to start search at
378 * @id: pointer to the allocated handle
380 * This is the allocate id function. It should be called with any
383 * If allocation from IDR's private freelist fails, idr_get_new_above() will
384 * return %-EAGAIN. The caller should retry the idr_pre_get() call to refill
385 * IDR's preallocation and then retry the idr_get_new_above() call.
387 * If the idr is full idr_get_new_above() will return %-ENOSPC.
389 * @id returns a value in the range @starting_id ... %0x7fffffff
391 int idr_get_new_above(struct idr *idp, void *ptr, int starting_id, int *id)
393 struct idr_layer *pa[MAX_IDR_LEVEL + 1];
396 rv = idr_get_empty_slot(idp, starting_id, pa, 0, idp);
398 return rv == -ENOMEM ? -EAGAIN : rv;
400 idr_fill_slot(ptr, rv, pa);
404 EXPORT_SYMBOL(idr_get_new_above);
407 * idr_preload - preload for idr_alloc()
408 * @gfp_mask: allocation mask to use for preloading
410 * Preload per-cpu layer buffer for idr_alloc(). Can only be used from
411 * process context and each idr_preload() invocation should be matched with
412 * idr_preload_end(). Note that preemption is disabled while preloaded.
414 * The first idr_alloc() in the preloaded section can be treated as if it
415 * were invoked with @gfp_mask used for preloading. This allows using more
416 * permissive allocation masks for idrs protected by spinlocks.
418 * For example, if idr_alloc() below fails, the failure can be treated as
419 * if idr_alloc() were called with GFP_KERNEL rather than GFP_NOWAIT.
421 * idr_preload(GFP_KERNEL);
424 * id = idr_alloc(idr, ptr, start, end, GFP_NOWAIT);
431 void idr_preload(gfp_t gfp_mask)
434 * Consuming preload buffer from non-process context breaks preload
435 * allocation guarantee. Disallow usage from those contexts.
437 WARN_ON_ONCE(in_interrupt());
438 might_sleep_if(gfp_mask & __GFP_WAIT);
443 * idr_alloc() is likely to succeed w/o full idr_layer buffer and
444 * return value from idr_alloc() needs to be checked for failure
445 * anyway. Silently give up if allocation fails. The caller can
446 * treat failures from idr_alloc() as if idr_alloc() were called
447 * with @gfp_mask which should be enough.
449 while (__this_cpu_read(idr_preload_cnt) < MAX_IDR_FREE) {
450 struct idr_layer *new;
453 new = kmem_cache_zalloc(idr_layer_cache, gfp_mask);
458 /* link the new one to per-cpu preload list */
459 new->ary[0] = __this_cpu_read(idr_preload_head);
460 __this_cpu_write(idr_preload_head, new);
461 __this_cpu_inc(idr_preload_cnt);
464 EXPORT_SYMBOL(idr_preload);
467 * idr_alloc - allocate new idr entry
468 * @idr: the (initialized) idr
469 * @ptr: pointer to be associated with the new id
470 * @start: the minimum id (inclusive)
471 * @end: the maximum id (exclusive, <= 0 for max)
472 * @gfp_mask: memory allocation flags
474 * Allocate an id in [start, end) and associate it with @ptr. If no ID is
475 * available in the specified range, returns -ENOSPC. On memory allocation
476 * failure, returns -ENOMEM.
478 * Note that @end is treated as max when <= 0. This is to always allow
479 * using @start + N as @end as long as N is inside integer range.
481 * The user is responsible for exclusively synchronizing all operations
482 * which may modify @idr. However, read-only accesses such as idr_find()
483 * or iteration can be performed under RCU read lock provided the user
484 * destroys @ptr in RCU-safe way after removal from idr.
486 int idr_alloc(struct idr *idr, void *ptr, int start, int end, gfp_t gfp_mask)
488 int max = end > 0 ? end - 1 : INT_MAX; /* inclusive upper limit */
489 struct idr_layer *pa[MAX_IDR_LEVEL + 1];
492 might_sleep_if(gfp_mask & __GFP_WAIT);
495 if (WARN_ON_ONCE(start < 0))
497 if (unlikely(max < start))
501 id = idr_get_empty_slot(idr, start, pa, gfp_mask, NULL);
502 if (unlikely(id < 0))
504 if (unlikely(id > max))
507 idr_fill_slot(ptr, id, pa);
510 EXPORT_SYMBOL_GPL(idr_alloc);
512 static void idr_remove_warning(int id)
515 "idr_remove called for id=%d which is not allocated.\n", id);
519 static void sub_remove(struct idr *idp, int shift, int id)
521 struct idr_layer *p = idp->top;
522 struct idr_layer **pa[MAX_IDR_LEVEL + 1];
523 struct idr_layer ***paa = &pa[0];
524 struct idr_layer *to_free;
530 while ((shift > 0) && p) {
531 n = (id >> shift) & IDR_MASK;
532 __clear_bit(n, p->bitmap);
538 if (likely(p != NULL && test_bit(n, p->bitmap))) {
539 __clear_bit(n, p->bitmap);
540 rcu_assign_pointer(p->ary[n], NULL);
542 while(*paa && ! --((**paa)->count)){
553 idr_remove_warning(id);
557 * idr_remove - remove the given id and free its slot
561 void idr_remove(struct idr *idp, int id)
564 struct idr_layer *to_free;
566 if (WARN_ON_ONCE(id < 0))
569 sub_remove(idp, (idp->layers - 1) * IDR_BITS, id);
570 if (idp->top && idp->top->count == 1 && (idp->layers > 1) &&
573 * Single child at leftmost slot: we can shrink the tree.
574 * This level is not needed anymore since when layers are
575 * inserted, they are inserted at the top of the existing
579 p = idp->top->ary[0];
580 rcu_assign_pointer(idp->top, p);
583 bitmap_clear(to_free->bitmap, 0, IDR_SIZE);
586 while (idp->id_free_cnt >= MAX_IDR_FREE) {
587 p = get_from_free_list(idp);
589 * Note: we don't call the rcu callback here, since the only
590 * layers that fall into the freelist are those that have been
593 kmem_cache_free(idr_layer_cache, p);
597 EXPORT_SYMBOL(idr_remove);
599 void __idr_remove_all(struct idr *idp)
604 struct idr_layer *pa[MAX_IDR_LEVEL + 1];
605 struct idr_layer **paa = &pa[0];
607 n = idp->layers * IDR_BITS;
609 rcu_assign_pointer(idp->top, NULL);
610 max = idr_max(idp->layers);
613 while (id >= 0 && id <= max) {
614 while (n > IDR_BITS && p) {
617 p = p->ary[(id >> n) & IDR_MASK];
622 /* Get the highest bit that the above add changed from 0->1. */
623 while (n < fls(id ^ bt_mask)) {
632 EXPORT_SYMBOL(__idr_remove_all);
635 * idr_destroy - release all cached layers within an idr tree
638 * Free all id mappings and all idp_layers. After this function, @idp is
639 * completely unused and can be freed / recycled. The caller is
640 * responsible for ensuring that no one else accesses @idp during or after
643 * A typical clean-up sequence for objects stored in an idr tree will use
644 * idr_for_each() to free all objects, if necessay, then idr_destroy() to
645 * free up the id mappings and cached idr_layers.
647 void idr_destroy(struct idr *idp)
649 __idr_remove_all(idp);
651 while (idp->id_free_cnt) {
652 struct idr_layer *p = get_from_free_list(idp);
653 kmem_cache_free(idr_layer_cache, p);
656 EXPORT_SYMBOL(idr_destroy);
659 * idr_find - return pointer for given id
663 * Return the pointer given the id it has been registered with. A %NULL
664 * return indicates that @id is not valid or you passed %NULL in
667 * This function can be called under rcu_read_lock(), given that the leaf
668 * pointers lifetimes are correctly managed.
670 void *idr_find(struct idr *idp, int id)
675 if (WARN_ON_ONCE(id < 0))
678 p = rcu_dereference_raw(idp->top);
681 n = (p->layer+1) * IDR_BITS;
683 if (id > idr_max(p->layer + 1))
689 BUG_ON(n != p->layer*IDR_BITS);
690 p = rcu_dereference_raw(p->ary[(id >> n) & IDR_MASK]);
694 EXPORT_SYMBOL(idr_find);
697 * idr_for_each - iterate through all stored pointers
699 * @fn: function to be called for each pointer
700 * @data: data passed back to callback function
702 * Iterate over the pointers registered with the given idr. The
703 * callback function will be called for each pointer currently
704 * registered, passing the id, the pointer and the data pointer passed
705 * to this function. It is not safe to modify the idr tree while in
706 * the callback, so functions such as idr_get_new and idr_remove are
709 * We check the return of @fn each time. If it returns anything other
710 * than %0, we break out and return that value.
712 * The caller must serialize idr_for_each() vs idr_get_new() and idr_remove().
714 int idr_for_each(struct idr *idp,
715 int (*fn)(int id, void *p, void *data), void *data)
717 int n, id, max, error = 0;
719 struct idr_layer *pa[MAX_IDR_LEVEL + 1];
720 struct idr_layer **paa = &pa[0];
722 n = idp->layers * IDR_BITS;
723 p = rcu_dereference_raw(idp->top);
724 max = idr_max(idp->layers);
727 while (id >= 0 && id <= max) {
731 p = rcu_dereference_raw(p->ary[(id >> n) & IDR_MASK]);
735 error = fn(id, (void *)p, data);
741 while (n < fls(id)) {
749 EXPORT_SYMBOL(idr_for_each);
752 * idr_get_next - lookup next object of id to given id.
754 * @nextidp: pointer to lookup key
756 * Returns pointer to registered object with id, which is next number to
757 * given id. After being looked up, *@nextidp will be updated for the next
760 * This function can be called under rcu_read_lock(), given that the leaf
761 * pointers lifetimes are correctly managed.
763 void *idr_get_next(struct idr *idp, int *nextidp)
765 struct idr_layer *p, *pa[MAX_IDR_LEVEL + 1];
766 struct idr_layer **paa = &pa[0];
771 p = rcu_dereference_raw(idp->top);
774 n = (p->layer + 1) * IDR_BITS;
775 max = idr_max(p->layer + 1);
777 while (id >= 0 && id <= max) {
781 p = rcu_dereference_raw(p->ary[(id >> n) & IDR_MASK]);
790 * Proceed to the next layer at the current level. Unlike
791 * idr_for_each(), @id isn't guaranteed to be aligned to
792 * layer boundary at this point and adding 1 << n may
793 * incorrectly skip IDs. Make sure we jump to the
794 * beginning of the next layer using round_up().
796 id = round_up(id + 1, 1 << n);
797 while (n < fls(id)) {
804 EXPORT_SYMBOL(idr_get_next);
808 * idr_replace - replace pointer for given id
810 * @ptr: pointer you want associated with the id
813 * Replace the pointer registered with an id and return the old value.
814 * A %-ENOENT return indicates that @id was not found.
815 * A %-EINVAL return indicates that @id was not within valid constraints.
817 * The caller must serialize with writers.
819 void *idr_replace(struct idr *idp, void *ptr, int id)
822 struct idr_layer *p, *old_p;
824 if (WARN_ON_ONCE(id < 0))
825 return ERR_PTR(-EINVAL);
829 return ERR_PTR(-EINVAL);
831 n = (p->layer+1) * IDR_BITS;
834 return ERR_PTR(-EINVAL);
837 while ((n > 0) && p) {
838 p = p->ary[(id >> n) & IDR_MASK];
843 if (unlikely(p == NULL || !test_bit(n, p->bitmap)))
844 return ERR_PTR(-ENOENT);
847 rcu_assign_pointer(p->ary[n], ptr);
851 EXPORT_SYMBOL(idr_replace);
853 void __init idr_init_cache(void)
855 idr_layer_cache = kmem_cache_create("idr_layer_cache",
856 sizeof(struct idr_layer), 0, SLAB_PANIC, NULL);
860 * idr_init - initialize idr handle
863 * This function is use to set up the handle (@idp) that you will pass
864 * to the rest of the functions.
866 void idr_init(struct idr *idp)
868 memset(idp, 0, sizeof(struct idr));
869 spin_lock_init(&idp->lock);
871 EXPORT_SYMBOL(idr_init);
875 * DOC: IDA description
876 * IDA - IDR based ID allocator
878 * This is id allocator without id -> pointer translation. Memory
879 * usage is much lower than full blown idr because each id only
880 * occupies a bit. ida uses a custom leaf node which contains
881 * IDA_BITMAP_BITS slots.
883 * 2007-04-25 written by Tejun Heo <htejun@gmail.com>
886 static void free_bitmap(struct ida *ida, struct ida_bitmap *bitmap)
890 if (!ida->free_bitmap) {
891 spin_lock_irqsave(&ida->idr.lock, flags);
892 if (!ida->free_bitmap) {
893 ida->free_bitmap = bitmap;
896 spin_unlock_irqrestore(&ida->idr.lock, flags);
903 * ida_pre_get - reserve resources for ida allocation
905 * @gfp_mask: memory allocation flag
907 * This function should be called prior to locking and calling the
908 * following function. It preallocates enough memory to satisfy the
909 * worst possible allocation.
911 * If the system is REALLY out of memory this function returns %0,
914 int ida_pre_get(struct ida *ida, gfp_t gfp_mask)
916 /* allocate idr_layers */
917 if (!idr_pre_get(&ida->idr, gfp_mask))
920 /* allocate free_bitmap */
921 if (!ida->free_bitmap) {
922 struct ida_bitmap *bitmap;
924 bitmap = kmalloc(sizeof(struct ida_bitmap), gfp_mask);
928 free_bitmap(ida, bitmap);
933 EXPORT_SYMBOL(ida_pre_get);
936 * ida_get_new_above - allocate new ID above or equal to a start id
938 * @starting_id: id to start search at
939 * @p_id: pointer to the allocated handle
941 * Allocate new ID above or equal to @starting_id. It should be called
942 * with any required locks.
944 * If memory is required, it will return %-EAGAIN, you should unlock
945 * and go back to the ida_pre_get() call. If the ida is full, it will
948 * @p_id returns a value in the range @starting_id ... %0x7fffffff.
950 int ida_get_new_above(struct ida *ida, int starting_id, int *p_id)
952 struct idr_layer *pa[MAX_IDR_LEVEL + 1];
953 struct ida_bitmap *bitmap;
955 int idr_id = starting_id / IDA_BITMAP_BITS;
956 int offset = starting_id % IDA_BITMAP_BITS;
960 /* get vacant slot */
961 t = idr_get_empty_slot(&ida->idr, idr_id, pa, 0, &ida->idr);
963 return t == -ENOMEM ? -EAGAIN : t;
965 if (t * IDA_BITMAP_BITS >= MAX_IDR_BIT)
972 /* if bitmap isn't there, create a new one */
973 bitmap = (void *)pa[0]->ary[idr_id & IDR_MASK];
975 spin_lock_irqsave(&ida->idr.lock, flags);
976 bitmap = ida->free_bitmap;
977 ida->free_bitmap = NULL;
978 spin_unlock_irqrestore(&ida->idr.lock, flags);
983 memset(bitmap, 0, sizeof(struct ida_bitmap));
984 rcu_assign_pointer(pa[0]->ary[idr_id & IDR_MASK],
989 /* lookup for empty slot */
990 t = find_next_zero_bit(bitmap->bitmap, IDA_BITMAP_BITS, offset);
991 if (t == IDA_BITMAP_BITS) {
992 /* no empty slot after offset, continue to the next chunk */
998 id = idr_id * IDA_BITMAP_BITS + t;
999 if (id >= MAX_IDR_BIT)
1002 __set_bit(t, bitmap->bitmap);
1003 if (++bitmap->nr_busy == IDA_BITMAP_BITS)
1004 idr_mark_full(pa, idr_id);
1008 /* Each leaf node can handle nearly a thousand slots and the
1009 * whole idea of ida is to have small memory foot print.
1010 * Throw away extra resources one by one after each successful
1013 if (ida->idr.id_free_cnt || ida->free_bitmap) {
1014 struct idr_layer *p = get_from_free_list(&ida->idr);
1016 kmem_cache_free(idr_layer_cache, p);
1021 EXPORT_SYMBOL(ida_get_new_above);
1024 * ida_remove - remove the given ID
1028 void ida_remove(struct ida *ida, int id)
1030 struct idr_layer *p = ida->idr.top;
1031 int shift = (ida->idr.layers - 1) * IDR_BITS;
1032 int idr_id = id / IDA_BITMAP_BITS;
1033 int offset = id % IDA_BITMAP_BITS;
1035 struct ida_bitmap *bitmap;
1037 /* clear full bits while looking up the leaf idr_layer */
1038 while ((shift > 0) && p) {
1039 n = (idr_id >> shift) & IDR_MASK;
1040 __clear_bit(n, p->bitmap);
1048 n = idr_id & IDR_MASK;
1049 __clear_bit(n, p->bitmap);
1051 bitmap = (void *)p->ary[n];
1052 if (!test_bit(offset, bitmap->bitmap))
1055 /* update bitmap and remove it if empty */
1056 __clear_bit(offset, bitmap->bitmap);
1057 if (--bitmap->nr_busy == 0) {
1058 __set_bit(n, p->bitmap); /* to please idr_remove() */
1059 idr_remove(&ida->idr, idr_id);
1060 free_bitmap(ida, bitmap);
1067 "ida_remove called for id=%d which is not allocated.\n", id);
1069 EXPORT_SYMBOL(ida_remove);
1072 * ida_destroy - release all cached layers within an ida tree
1075 void ida_destroy(struct ida *ida)
1077 idr_destroy(&ida->idr);
1078 kfree(ida->free_bitmap);
1080 EXPORT_SYMBOL(ida_destroy);
1083 * ida_simple_get - get a new id.
1084 * @ida: the (initialized) ida.
1085 * @start: the minimum id (inclusive, < 0x8000000)
1086 * @end: the maximum id (exclusive, < 0x8000000 or 0)
1087 * @gfp_mask: memory allocation flags
1089 * Allocates an id in the range start <= id < end, or returns -ENOSPC.
1090 * On memory allocation failure, returns -ENOMEM.
1092 * Use ida_simple_remove() to get rid of an id.
1094 int ida_simple_get(struct ida *ida, unsigned int start, unsigned int end,
1099 unsigned long flags;
1101 BUG_ON((int)start < 0);
1102 BUG_ON((int)end < 0);
1107 BUG_ON(end < start);
1112 if (!ida_pre_get(ida, gfp_mask))
1115 spin_lock_irqsave(&simple_ida_lock, flags);
1116 ret = ida_get_new_above(ida, start, &id);
1119 ida_remove(ida, id);
1125 spin_unlock_irqrestore(&simple_ida_lock, flags);
1127 if (unlikely(ret == -EAGAIN))
1132 EXPORT_SYMBOL(ida_simple_get);
1135 * ida_simple_remove - remove an allocated id.
1136 * @ida: the (initialized) ida.
1137 * @id: the id returned by ida_simple_get.
1139 void ida_simple_remove(struct ida *ida, unsigned int id)
1141 unsigned long flags;
1143 BUG_ON((int)id < 0);
1144 spin_lock_irqsave(&simple_ida_lock, flags);
1145 ida_remove(ida, id);
1146 spin_unlock_irqrestore(&simple_ida_lock, flags);
1148 EXPORT_SYMBOL(ida_simple_remove);
1151 * ida_init - initialize ida handle
1154 * This function is use to set up the handle (@ida) that you will pass
1155 * to the rest of the functions.
1157 void ida_init(struct ida *ida)
1159 memset(ida, 0, sizeof(struct ida));
1160 idr_init(&ida->idr);
1163 EXPORT_SYMBOL(ida_init);