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);
110 * Try to allocate directly from kmem_cache. We want to try this
111 * before preload buffer; otherwise, non-preloading idr_alloc()
112 * users will end up taking advantage of preloading ones. As the
113 * following is allowed to fail for preloaded cases, suppress
116 new = kmem_cache_zalloc(idr_layer_cache, gfp_mask | __GFP_NOWARN);
121 * Try to fetch one from the per-cpu preload buffer if in process
122 * context. See idr_preload() for details.
124 if (!in_interrupt()) {
126 new = __this_cpu_read(idr_preload_head);
128 __this_cpu_write(idr_preload_head, new->ary[0]);
129 __this_cpu_dec(idr_preload_cnt);
138 * Both failed. Try kmem_cache again w/o adding __GFP_NOWARN so
139 * that memory allocation failure warning is printed as intended.
141 return kmem_cache_zalloc(idr_layer_cache, gfp_mask);
144 static void idr_layer_rcu_free(struct rcu_head *head)
146 struct idr_layer *layer;
148 layer = container_of(head, struct idr_layer, rcu_head);
149 kmem_cache_free(idr_layer_cache, layer);
152 static inline void free_layer(struct idr *idr, struct idr_layer *p)
154 if (idr->hint && idr->hint == p)
155 RCU_INIT_POINTER(idr->hint, NULL);
156 call_rcu(&p->rcu_head, idr_layer_rcu_free);
159 /* only called when idp->lock is held */
160 static void __move_to_free_list(struct idr *idp, struct idr_layer *p)
162 p->ary[0] = idp->id_free;
167 static void move_to_free_list(struct idr *idp, struct idr_layer *p)
172 * Depends on the return element being zeroed.
174 spin_lock_irqsave(&idp->lock, flags);
175 __move_to_free_list(idp, p);
176 spin_unlock_irqrestore(&idp->lock, flags);
179 static void idr_mark_full(struct idr_layer **pa, int id)
181 struct idr_layer *p = pa[0];
184 __set_bit(id & IDR_MASK, p->bitmap);
186 * If this layer is full mark the bit in the layer above to
187 * show that this part of the radix tree is full. This may
188 * complete the layer above and require walking up the radix
191 while (bitmap_full(p->bitmap, IDR_SIZE)) {
195 __set_bit((id & IDR_MASK), p->bitmap);
199 int __idr_pre_get(struct idr *idp, gfp_t gfp_mask)
201 while (idp->id_free_cnt < MAX_IDR_FREE) {
202 struct idr_layer *new;
203 new = kmem_cache_zalloc(idr_layer_cache, gfp_mask);
206 move_to_free_list(idp, new);
210 EXPORT_SYMBOL(__idr_pre_get);
213 * sub_alloc - try to allocate an id without growing the tree depth
215 * @starting_id: id to start search at
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(struct idr *idr, void *ptr, int id,
367 struct idr_layer **pa)
369 /* update hint used for lookup, cleared from free_layer() */
370 rcu_assign_pointer(idr->hint, pa[0]);
372 rcu_assign_pointer(pa[0]->ary[id & IDR_MASK], (struct idr_layer *)ptr);
374 idr_mark_full(pa, id);
377 int __idr_get_new_above(struct idr *idp, void *ptr, int starting_id, int *id)
379 struct idr_layer *pa[MAX_IDR_LEVEL + 1];
382 rv = idr_get_empty_slot(idp, starting_id, pa, 0, idp);
384 return rv == -ENOMEM ? -EAGAIN : rv;
386 idr_fill_slot(idp, ptr, rv, pa);
390 EXPORT_SYMBOL(__idr_get_new_above);
393 * idr_preload - preload for idr_alloc()
394 * @gfp_mask: allocation mask to use for preloading
396 * Preload per-cpu layer buffer for idr_alloc(). Can only be used from
397 * process context and each idr_preload() invocation should be matched with
398 * idr_preload_end(). Note that preemption is disabled while preloaded.
400 * The first idr_alloc() in the preloaded section can be treated as if it
401 * were invoked with @gfp_mask used for preloading. This allows using more
402 * permissive allocation masks for idrs protected by spinlocks.
404 * For example, if idr_alloc() below fails, the failure can be treated as
405 * if idr_alloc() were called with GFP_KERNEL rather than GFP_NOWAIT.
407 * idr_preload(GFP_KERNEL);
410 * id = idr_alloc(idr, ptr, start, end, GFP_NOWAIT);
417 void idr_preload(gfp_t gfp_mask)
420 * Consuming preload buffer from non-process context breaks preload
421 * allocation guarantee. Disallow usage from those contexts.
423 WARN_ON_ONCE(in_interrupt());
424 might_sleep_if(gfp_mask & __GFP_WAIT);
429 * idr_alloc() is likely to succeed w/o full idr_layer buffer and
430 * return value from idr_alloc() needs to be checked for failure
431 * anyway. Silently give up if allocation fails. The caller can
432 * treat failures from idr_alloc() as if idr_alloc() were called
433 * with @gfp_mask which should be enough.
435 while (__this_cpu_read(idr_preload_cnt) < MAX_IDR_FREE) {
436 struct idr_layer *new;
439 new = kmem_cache_zalloc(idr_layer_cache, gfp_mask);
444 /* link the new one to per-cpu preload list */
445 new->ary[0] = __this_cpu_read(idr_preload_head);
446 __this_cpu_write(idr_preload_head, new);
447 __this_cpu_inc(idr_preload_cnt);
450 EXPORT_SYMBOL(idr_preload);
453 * idr_alloc - allocate new idr entry
454 * @idr: the (initialized) idr
455 * @ptr: pointer to be associated with the new id
456 * @start: the minimum id (inclusive)
457 * @end: the maximum id (exclusive, <= 0 for max)
458 * @gfp_mask: memory allocation flags
460 * Allocate an id in [start, end) and associate it with @ptr. If no ID is
461 * available in the specified range, returns -ENOSPC. On memory allocation
462 * failure, returns -ENOMEM.
464 * Note that @end is treated as max when <= 0. This is to always allow
465 * using @start + N as @end as long as N is inside integer range.
467 * The user is responsible for exclusively synchronizing all operations
468 * which may modify @idr. However, read-only accesses such as idr_find()
469 * or iteration can be performed under RCU read lock provided the user
470 * destroys @ptr in RCU-safe way after removal from idr.
472 int idr_alloc(struct idr *idr, void *ptr, int start, int end, gfp_t gfp_mask)
474 int max = end > 0 ? end - 1 : INT_MAX; /* inclusive upper limit */
475 struct idr_layer *pa[MAX_IDR_LEVEL + 1];
478 might_sleep_if(gfp_mask & __GFP_WAIT);
481 if (WARN_ON_ONCE(start < 0))
483 if (unlikely(max < start))
487 id = idr_get_empty_slot(idr, start, pa, gfp_mask, NULL);
488 if (unlikely(id < 0))
490 if (unlikely(id > max))
493 idr_fill_slot(idr, ptr, id, pa);
496 EXPORT_SYMBOL_GPL(idr_alloc);
499 * idr_alloc_cyclic - allocate new idr entry in a cyclical fashion
500 * @idr: the (initialized) idr
501 * @ptr: pointer to be associated with the new id
502 * @start: the minimum id (inclusive)
503 * @end: the maximum id (exclusive, <= 0 for max)
504 * @gfp_mask: memory allocation flags
506 * Essentially the same as idr_alloc, but prefers to allocate progressively
507 * higher ids if it can. If the "cur" counter wraps, then it will start again
508 * at the "start" end of the range and allocate one that has already been used.
510 int idr_alloc_cyclic(struct idr *idr, void *ptr, int start, int end,
515 id = idr_alloc(idr, ptr, max(start, idr->cur), end, gfp_mask);
517 id = idr_alloc(idr, ptr, start, end, gfp_mask);
523 EXPORT_SYMBOL(idr_alloc_cyclic);
525 static void idr_remove_warning(int id)
527 WARN(1, "idr_remove called for id=%d which is not allocated.\n", id);
530 static void sub_remove(struct idr *idp, int shift, int id)
532 struct idr_layer *p = idp->top;
533 struct idr_layer **pa[MAX_IDR_LEVEL + 1];
534 struct idr_layer ***paa = &pa[0];
535 struct idr_layer *to_free;
541 while ((shift > 0) && p) {
542 n = (id >> shift) & IDR_MASK;
543 __clear_bit(n, p->bitmap);
549 if (likely(p != NULL && test_bit(n, p->bitmap))) {
550 __clear_bit(n, p->bitmap);
551 rcu_assign_pointer(p->ary[n], NULL);
553 while(*paa && ! --((**paa)->count)){
555 free_layer(idp, to_free);
562 free_layer(idp, to_free);
564 idr_remove_warning(id);
568 * idr_remove - remove the given id and free its slot
572 void idr_remove(struct idr *idp, int id)
575 struct idr_layer *to_free;
580 sub_remove(idp, (idp->layers - 1) * IDR_BITS, id);
581 if (idp->top && idp->top->count == 1 && (idp->layers > 1) &&
584 * Single child at leftmost slot: we can shrink the tree.
585 * This level is not needed anymore since when layers are
586 * inserted, they are inserted at the top of the existing
590 p = idp->top->ary[0];
591 rcu_assign_pointer(idp->top, p);
594 bitmap_clear(to_free->bitmap, 0, IDR_SIZE);
595 free_layer(idp, to_free);
597 while (idp->id_free_cnt >= MAX_IDR_FREE) {
598 p = get_from_free_list(idp);
600 * Note: we don't call the rcu callback here, since the only
601 * layers that fall into the freelist are those that have been
604 kmem_cache_free(idr_layer_cache, p);
608 EXPORT_SYMBOL(idr_remove);
610 void __idr_remove_all(struct idr *idp)
615 struct idr_layer *pa[MAX_IDR_LEVEL + 1];
616 struct idr_layer **paa = &pa[0];
618 n = idp->layers * IDR_BITS;
620 rcu_assign_pointer(idp->top, NULL);
621 max = idr_max(idp->layers);
624 while (id >= 0 && id <= max) {
625 while (n > IDR_BITS && p) {
628 p = p->ary[(id >> n) & IDR_MASK];
633 /* Get the highest bit that the above add changed from 0->1. */
634 while (n < fls(id ^ bt_mask)) {
643 EXPORT_SYMBOL(__idr_remove_all);
646 * idr_destroy - release all cached layers within an idr tree
649 * Free all id mappings and all idp_layers. After this function, @idp is
650 * completely unused and can be freed / recycled. The caller is
651 * responsible for ensuring that no one else accesses @idp during or after
654 * A typical clean-up sequence for objects stored in an idr tree will use
655 * idr_for_each() to free all objects, if necessay, then idr_destroy() to
656 * free up the id mappings and cached idr_layers.
658 void idr_destroy(struct idr *idp)
660 __idr_remove_all(idp);
662 while (idp->id_free_cnt) {
663 struct idr_layer *p = get_from_free_list(idp);
664 kmem_cache_free(idr_layer_cache, p);
667 EXPORT_SYMBOL(idr_destroy);
669 void *idr_find_slowpath(struct idr *idp, int id)
677 p = rcu_dereference_raw(idp->top);
680 n = (p->layer+1) * IDR_BITS;
682 if (id > idr_max(p->layer + 1))
688 BUG_ON(n != p->layer*IDR_BITS);
689 p = rcu_dereference_raw(p->ary[(id >> n) & IDR_MASK]);
693 EXPORT_SYMBOL(idr_find_slowpath);
696 * idr_for_each - iterate through all stored pointers
698 * @fn: function to be called for each pointer
699 * @data: data passed back to callback function
701 * Iterate over the pointers registered with the given idr. The
702 * callback function will be called for each pointer currently
703 * registered, passing the id, the pointer and the data pointer passed
704 * to this function. It is not safe to modify the idr tree while in
705 * the callback, so functions such as idr_get_new and idr_remove are
708 * We check the return of @fn each time. If it returns anything other
709 * than %0, we break out and return that value.
711 * The caller must serialize idr_for_each() vs idr_get_new() and idr_remove().
713 int idr_for_each(struct idr *idp,
714 int (*fn)(int id, void *p, void *data), void *data)
716 int n, id, max, error = 0;
718 struct idr_layer *pa[MAX_IDR_LEVEL + 1];
719 struct idr_layer **paa = &pa[0];
721 n = idp->layers * IDR_BITS;
722 p = rcu_dereference_raw(idp->top);
723 max = idr_max(idp->layers);
726 while (id >= 0 && id <= max) {
730 p = rcu_dereference_raw(p->ary[(id >> n) & IDR_MASK]);
734 error = fn(id, (void *)p, data);
740 while (n < fls(id)) {
748 EXPORT_SYMBOL(idr_for_each);
751 * idr_get_next - lookup next object of id to given id.
753 * @nextidp: pointer to lookup key
755 * Returns pointer to registered object with id, which is next number to
756 * given id. After being looked up, *@nextidp will be updated for the next
759 * This function can be called under rcu_read_lock(), given that the leaf
760 * pointers lifetimes are correctly managed.
762 void *idr_get_next(struct idr *idp, int *nextidp)
764 struct idr_layer *p, *pa[MAX_IDR_LEVEL + 1];
765 struct idr_layer **paa = &pa[0];
770 p = rcu_dereference_raw(idp->top);
773 n = (p->layer + 1) * IDR_BITS;
774 max = idr_max(p->layer + 1);
776 while (id >= 0 && id <= max) {
780 p = rcu_dereference_raw(p->ary[(id >> n) & IDR_MASK]);
789 * Proceed to the next layer at the current level. Unlike
790 * idr_for_each(), @id isn't guaranteed to be aligned to
791 * layer boundary at this point and adding 1 << n may
792 * incorrectly skip IDs. Make sure we jump to the
793 * beginning of the next layer using round_up().
795 id = round_up(id + 1, 1 << n);
796 while (n < fls(id)) {
803 EXPORT_SYMBOL(idr_get_next);
807 * idr_replace - replace pointer for given id
809 * @ptr: pointer you want associated with the id
812 * Replace the pointer registered with an id and return the old value.
813 * A %-ENOENT return indicates that @id was not found.
814 * A %-EINVAL return indicates that @id was not within valid constraints.
816 * The caller must serialize with writers.
818 void *idr_replace(struct idr *idp, void *ptr, int id)
821 struct idr_layer *p, *old_p;
824 return ERR_PTR(-EINVAL);
828 return ERR_PTR(-EINVAL);
830 n = (p->layer+1) * IDR_BITS;
833 return ERR_PTR(-EINVAL);
836 while ((n > 0) && p) {
837 p = p->ary[(id >> n) & IDR_MASK];
842 if (unlikely(p == NULL || !test_bit(n, p->bitmap)))
843 return ERR_PTR(-ENOENT);
846 rcu_assign_pointer(p->ary[n], ptr);
850 EXPORT_SYMBOL(idr_replace);
852 void __init idr_init_cache(void)
854 idr_layer_cache = kmem_cache_create("idr_layer_cache",
855 sizeof(struct idr_layer), 0, SLAB_PANIC, NULL);
859 * idr_init - initialize idr handle
862 * This function is use to set up the handle (@idp) that you will pass
863 * to the rest of the functions.
865 void idr_init(struct idr *idp)
867 memset(idp, 0, sizeof(struct idr));
868 spin_lock_init(&idp->lock);
870 EXPORT_SYMBOL(idr_init);
874 * DOC: IDA description
875 * IDA - IDR based ID allocator
877 * This is id allocator without id -> pointer translation. Memory
878 * usage is much lower than full blown idr because each id only
879 * occupies a bit. ida uses a custom leaf node which contains
880 * IDA_BITMAP_BITS slots.
882 * 2007-04-25 written by Tejun Heo <htejun@gmail.com>
885 static void free_bitmap(struct ida *ida, struct ida_bitmap *bitmap)
889 if (!ida->free_bitmap) {
890 spin_lock_irqsave(&ida->idr.lock, flags);
891 if (!ida->free_bitmap) {
892 ida->free_bitmap = bitmap;
895 spin_unlock_irqrestore(&ida->idr.lock, flags);
902 * ida_pre_get - reserve resources for ida allocation
904 * @gfp_mask: memory allocation flag
906 * This function should be called prior to locking and calling the
907 * following function. It preallocates enough memory to satisfy the
908 * worst possible allocation.
910 * If the system is REALLY out of memory this function returns %0,
913 int ida_pre_get(struct ida *ida, gfp_t gfp_mask)
915 /* allocate idr_layers */
916 if (!__idr_pre_get(&ida->idr, gfp_mask))
919 /* allocate free_bitmap */
920 if (!ida->free_bitmap) {
921 struct ida_bitmap *bitmap;
923 bitmap = kmalloc(sizeof(struct ida_bitmap), gfp_mask);
927 free_bitmap(ida, bitmap);
932 EXPORT_SYMBOL(ida_pre_get);
935 * ida_get_new_above - allocate new ID above or equal to a start id
937 * @starting_id: id to start search at
938 * @p_id: pointer to the allocated handle
940 * Allocate new ID above or equal to @starting_id. It should be called
941 * with any required locks.
943 * If memory is required, it will return %-EAGAIN, you should unlock
944 * and go back to the ida_pre_get() call. If the ida is full, it will
947 * @p_id returns a value in the range @starting_id ... %0x7fffffff.
949 int ida_get_new_above(struct ida *ida, int starting_id, int *p_id)
951 struct idr_layer *pa[MAX_IDR_LEVEL + 1];
952 struct ida_bitmap *bitmap;
954 int idr_id = starting_id / IDA_BITMAP_BITS;
955 int offset = starting_id % IDA_BITMAP_BITS;
959 /* get vacant slot */
960 t = idr_get_empty_slot(&ida->idr, idr_id, pa, 0, &ida->idr);
962 return t == -ENOMEM ? -EAGAIN : t;
964 if (t * IDA_BITMAP_BITS >= MAX_IDR_BIT)
971 /* if bitmap isn't there, create a new one */
972 bitmap = (void *)pa[0]->ary[idr_id & IDR_MASK];
974 spin_lock_irqsave(&ida->idr.lock, flags);
975 bitmap = ida->free_bitmap;
976 ida->free_bitmap = NULL;
977 spin_unlock_irqrestore(&ida->idr.lock, flags);
982 memset(bitmap, 0, sizeof(struct ida_bitmap));
983 rcu_assign_pointer(pa[0]->ary[idr_id & IDR_MASK],
988 /* lookup for empty slot */
989 t = find_next_zero_bit(bitmap->bitmap, IDA_BITMAP_BITS, offset);
990 if (t == IDA_BITMAP_BITS) {
991 /* no empty slot after offset, continue to the next chunk */
997 id = idr_id * IDA_BITMAP_BITS + t;
998 if (id >= MAX_IDR_BIT)
1001 __set_bit(t, bitmap->bitmap);
1002 if (++bitmap->nr_busy == IDA_BITMAP_BITS)
1003 idr_mark_full(pa, idr_id);
1007 /* Each leaf node can handle nearly a thousand slots and the
1008 * whole idea of ida is to have small memory foot print.
1009 * Throw away extra resources one by one after each successful
1012 if (ida->idr.id_free_cnt || ida->free_bitmap) {
1013 struct idr_layer *p = get_from_free_list(&ida->idr);
1015 kmem_cache_free(idr_layer_cache, p);
1020 EXPORT_SYMBOL(ida_get_new_above);
1023 * ida_remove - remove the given ID
1027 void ida_remove(struct ida *ida, int id)
1029 struct idr_layer *p = ida->idr.top;
1030 int shift = (ida->idr.layers - 1) * IDR_BITS;
1031 int idr_id = id / IDA_BITMAP_BITS;
1032 int offset = id % IDA_BITMAP_BITS;
1034 struct ida_bitmap *bitmap;
1036 /* clear full bits while looking up the leaf idr_layer */
1037 while ((shift > 0) && p) {
1038 n = (idr_id >> shift) & IDR_MASK;
1039 __clear_bit(n, p->bitmap);
1047 n = idr_id & IDR_MASK;
1048 __clear_bit(n, p->bitmap);
1050 bitmap = (void *)p->ary[n];
1051 if (!test_bit(offset, bitmap->bitmap))
1054 /* update bitmap and remove it if empty */
1055 __clear_bit(offset, bitmap->bitmap);
1056 if (--bitmap->nr_busy == 0) {
1057 __set_bit(n, p->bitmap); /* to please idr_remove() */
1058 idr_remove(&ida->idr, idr_id);
1059 free_bitmap(ida, bitmap);
1065 WARN(1, "ida_remove called for id=%d which is not allocated.\n", id);
1067 EXPORT_SYMBOL(ida_remove);
1070 * ida_destroy - release all cached layers within an ida tree
1073 void ida_destroy(struct ida *ida)
1075 idr_destroy(&ida->idr);
1076 kfree(ida->free_bitmap);
1078 EXPORT_SYMBOL(ida_destroy);
1081 * ida_simple_get - get a new id.
1082 * @ida: the (initialized) ida.
1083 * @start: the minimum id (inclusive, < 0x8000000)
1084 * @end: the maximum id (exclusive, < 0x8000000 or 0)
1085 * @gfp_mask: memory allocation flags
1087 * Allocates an id in the range start <= id < end, or returns -ENOSPC.
1088 * On memory allocation failure, returns -ENOMEM.
1090 * Use ida_simple_remove() to get rid of an id.
1092 int ida_simple_get(struct ida *ida, unsigned int start, unsigned int end,
1097 unsigned long flags;
1099 BUG_ON((int)start < 0);
1100 BUG_ON((int)end < 0);
1105 BUG_ON(end < start);
1110 if (!ida_pre_get(ida, gfp_mask))
1113 spin_lock_irqsave(&simple_ida_lock, flags);
1114 ret = ida_get_new_above(ida, start, &id);
1117 ida_remove(ida, id);
1123 spin_unlock_irqrestore(&simple_ida_lock, flags);
1125 if (unlikely(ret == -EAGAIN))
1130 EXPORT_SYMBOL(ida_simple_get);
1133 * ida_simple_remove - remove an allocated id.
1134 * @ida: the (initialized) ida.
1135 * @id: the id returned by ida_simple_get.
1137 void ida_simple_remove(struct ida *ida, unsigned int id)
1139 unsigned long flags;
1141 BUG_ON((int)id < 0);
1142 spin_lock_irqsave(&simple_ida_lock, flags);
1143 ida_remove(ida, id);
1144 spin_unlock_irqrestore(&simple_ida_lock, flags);
1146 EXPORT_SYMBOL(ida_simple_remove);
1149 * ida_init - initialize ida handle
1152 * This function is use to set up the handle (@ida) that you will pass
1153 * to the rest of the functions.
1155 void ida_init(struct ida *ida)
1157 memset(ida, 0, sizeof(struct ida));
1158 idr_init(&ida->idr);
1161 EXPORT_SYMBOL(ida_init);