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![Manfred Spraul](/assets/img/avatar_default.png)
The last patch to lib/idr.c caused a bug if idr_get_new_above() was called on an empty idr. Usually, nodes stay on the same layer. New layers are added to the top of the tree. The exception is idr_get_new_above() on an empty tree: In this case, the new root node is first added on layer 0, then moved upwards. p->layer was not updated. As usual: You shall never rely on the source code comments, they will only mislead you. Signed-off-by: Manfred Spraul <manfred@colorfullife.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
892 lines
21 KiB
C
892 lines
21 KiB
C
/*
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* 2002-10-18 written by Jim Houston jim.houston@ccur.com
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* Copyright (C) 2002 by Concurrent Computer Corporation
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* Distributed under the GNU GPL license version 2.
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*
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* Modified by George Anzinger to reuse immediately and to use
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* find bit instructions. Also removed _irq on spinlocks.
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*
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* Modified by Nadia Derbey to make it RCU safe.
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*
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* Small id to pointer translation service.
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*
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* It uses a radix tree like structure as a sparse array indexed
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* by the id to obtain the pointer. The bitmap makes allocating
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* a new id quick.
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*
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* You call it to allocate an id (an int) an associate with that id a
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* pointer or what ever, we treat it as a (void *). You can pass this
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* id to a user for him to pass back at a later time. You then pass
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* that id to this code and it returns your pointer.
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* You can release ids at any time. When all ids are released, most of
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* the memory is returned (we keep IDR_FREE_MAX) in a local pool so we
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* don't need to go to the memory "store" during an id allocate, just
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* so you don't need to be too concerned about locking and conflicts
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* with the slab allocator.
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*/
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#ifndef TEST // to test in user space...
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#include <linux/slab.h>
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#include <linux/init.h>
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#include <linux/module.h>
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#endif
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#include <linux/err.h>
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#include <linux/string.h>
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#include <linux/idr.h>
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static struct kmem_cache *idr_layer_cache;
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static struct idr_layer *get_from_free_list(struct idr *idp)
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{
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struct idr_layer *p;
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unsigned long flags;
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spin_lock_irqsave(&idp->lock, flags);
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if ((p = idp->id_free)) {
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idp->id_free = p->ary[0];
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idp->id_free_cnt--;
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p->ary[0] = NULL;
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}
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spin_unlock_irqrestore(&idp->lock, flags);
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return(p);
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}
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static void idr_layer_rcu_free(struct rcu_head *head)
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{
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struct idr_layer *layer;
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layer = container_of(head, struct idr_layer, rcu_head);
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kmem_cache_free(idr_layer_cache, layer);
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}
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static inline void free_layer(struct idr_layer *p)
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{
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call_rcu(&p->rcu_head, idr_layer_rcu_free);
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}
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/* only called when idp->lock is held */
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static void __move_to_free_list(struct idr *idp, struct idr_layer *p)
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{
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p->ary[0] = idp->id_free;
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idp->id_free = p;
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idp->id_free_cnt++;
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}
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static void move_to_free_list(struct idr *idp, struct idr_layer *p)
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{
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unsigned long flags;
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/*
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* Depends on the return element being zeroed.
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*/
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spin_lock_irqsave(&idp->lock, flags);
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__move_to_free_list(idp, p);
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spin_unlock_irqrestore(&idp->lock, flags);
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}
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static void idr_mark_full(struct idr_layer **pa, int id)
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{
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struct idr_layer *p = pa[0];
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int l = 0;
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__set_bit(id & IDR_MASK, &p->bitmap);
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/*
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* If this layer is full mark the bit in the layer above to
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* show that this part of the radix tree is full. This may
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* complete the layer above and require walking up the radix
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* tree.
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*/
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while (p->bitmap == IDR_FULL) {
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if (!(p = pa[++l]))
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break;
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id = id >> IDR_BITS;
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__set_bit((id & IDR_MASK), &p->bitmap);
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}
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}
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/**
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* idr_pre_get - reserver resources for idr allocation
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* @idp: idr handle
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* @gfp_mask: memory allocation flags
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*
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* This function should be called prior to locking and calling the
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* idr_get_new* functions. It preallocates enough memory to satisfy
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* the worst possible allocation.
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*
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* If the system is REALLY out of memory this function returns 0,
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* otherwise 1.
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*/
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int idr_pre_get(struct idr *idp, gfp_t gfp_mask)
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{
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while (idp->id_free_cnt < IDR_FREE_MAX) {
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struct idr_layer *new;
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new = kmem_cache_alloc(idr_layer_cache, gfp_mask);
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if (new == NULL)
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return (0);
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move_to_free_list(idp, new);
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}
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return 1;
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}
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EXPORT_SYMBOL(idr_pre_get);
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static int sub_alloc(struct idr *idp, int *starting_id, struct idr_layer **pa)
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{
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int n, m, sh;
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struct idr_layer *p, *new;
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int l, id, oid;
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unsigned long bm;
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id = *starting_id;
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restart:
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p = idp->top;
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l = idp->layers;
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pa[l--] = NULL;
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while (1) {
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/*
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* We run around this while until we reach the leaf node...
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*/
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n = (id >> (IDR_BITS*l)) & IDR_MASK;
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bm = ~p->bitmap;
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m = find_next_bit(&bm, IDR_SIZE, n);
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if (m == IDR_SIZE) {
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/* no space available go back to previous layer. */
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l++;
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oid = id;
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id = (id | ((1 << (IDR_BITS * l)) - 1)) + 1;
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/* if already at the top layer, we need to grow */
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if (!(p = pa[l])) {
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*starting_id = id;
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return IDR_NEED_TO_GROW;
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}
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/* If we need to go up one layer, continue the
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* loop; otherwise, restart from the top.
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*/
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sh = IDR_BITS * (l + 1);
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if (oid >> sh == id >> sh)
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continue;
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else
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goto restart;
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}
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if (m != n) {
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sh = IDR_BITS*l;
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id = ((id >> sh) ^ n ^ m) << sh;
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}
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if ((id >= MAX_ID_BIT) || (id < 0))
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return IDR_NOMORE_SPACE;
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if (l == 0)
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break;
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/*
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* Create the layer below if it is missing.
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*/
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if (!p->ary[m]) {
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new = get_from_free_list(idp);
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if (!new)
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return -1;
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new->layer = l-1;
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rcu_assign_pointer(p->ary[m], new);
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p->count++;
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}
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pa[l--] = p;
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p = p->ary[m];
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}
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pa[l] = p;
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return id;
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}
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static int idr_get_empty_slot(struct idr *idp, int starting_id,
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struct idr_layer **pa)
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{
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struct idr_layer *p, *new;
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int layers, v, id;
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unsigned long flags;
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id = starting_id;
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build_up:
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p = idp->top;
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layers = idp->layers;
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if (unlikely(!p)) {
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if (!(p = get_from_free_list(idp)))
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return -1;
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p->layer = 0;
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layers = 1;
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}
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/*
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* Add a new layer to the top of the tree if the requested
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* id is larger than the currently allocated space.
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*/
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while ((layers < (MAX_LEVEL - 1)) && (id >= (1 << (layers*IDR_BITS)))) {
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layers++;
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if (!p->count) {
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/* special case: if the tree is currently empty,
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* then we grow the tree by moving the top node
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* upwards.
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*/
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p->layer++;
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continue;
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}
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if (!(new = get_from_free_list(idp))) {
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/*
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* The allocation failed. If we built part of
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* the structure tear it down.
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*/
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spin_lock_irqsave(&idp->lock, flags);
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for (new = p; p && p != idp->top; new = p) {
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p = p->ary[0];
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new->ary[0] = NULL;
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new->bitmap = new->count = 0;
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__move_to_free_list(idp, new);
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}
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spin_unlock_irqrestore(&idp->lock, flags);
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return -1;
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}
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new->ary[0] = p;
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new->count = 1;
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new->layer = layers-1;
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if (p->bitmap == IDR_FULL)
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__set_bit(0, &new->bitmap);
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p = new;
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}
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rcu_assign_pointer(idp->top, p);
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idp->layers = layers;
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v = sub_alloc(idp, &id, pa);
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if (v == IDR_NEED_TO_GROW)
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goto build_up;
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return(v);
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}
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static int idr_get_new_above_int(struct idr *idp, void *ptr, int starting_id)
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{
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struct idr_layer *pa[MAX_LEVEL];
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int id;
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id = idr_get_empty_slot(idp, starting_id, pa);
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if (id >= 0) {
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/*
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* Successfully found an empty slot. Install the user
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* pointer and mark the slot full.
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*/
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rcu_assign_pointer(pa[0]->ary[id & IDR_MASK],
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(struct idr_layer *)ptr);
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pa[0]->count++;
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idr_mark_full(pa, id);
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}
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return id;
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}
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/**
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* idr_get_new_above - allocate new idr entry above or equal to a start id
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* @idp: idr handle
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* @ptr: pointer you want associated with the ide
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* @start_id: id to start search at
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* @id: pointer to the allocated handle
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*
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* This is the allocate id function. It should be called with any
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* required locks.
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*
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* If memory is required, it will return -EAGAIN, you should unlock
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* and go back to the idr_pre_get() call. If the idr is full, it will
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* return -ENOSPC.
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*
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* @id returns a value in the range 0 ... 0x7fffffff
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*/
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int idr_get_new_above(struct idr *idp, void *ptr, int starting_id, int *id)
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{
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int rv;
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rv = idr_get_new_above_int(idp, ptr, starting_id);
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/*
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* This is a cheap hack until the IDR code can be fixed to
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* return proper error values.
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*/
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if (rv < 0)
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return _idr_rc_to_errno(rv);
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*id = rv;
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return 0;
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}
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EXPORT_SYMBOL(idr_get_new_above);
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/**
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* idr_get_new - allocate new idr entry
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* @idp: idr handle
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* @ptr: pointer you want associated with the ide
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* @id: pointer to the allocated handle
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*
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* This is the allocate id function. It should be called with any
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* required locks.
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*
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* If memory is required, it will return -EAGAIN, you should unlock
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* and go back to the idr_pre_get() call. If the idr is full, it will
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* return -ENOSPC.
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*
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* @id returns a value in the range 0 ... 0x7fffffff
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*/
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int idr_get_new(struct idr *idp, void *ptr, int *id)
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{
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int rv;
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rv = idr_get_new_above_int(idp, ptr, 0);
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/*
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* This is a cheap hack until the IDR code can be fixed to
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* return proper error values.
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*/
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if (rv < 0)
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return _idr_rc_to_errno(rv);
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*id = rv;
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return 0;
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}
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EXPORT_SYMBOL(idr_get_new);
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static void idr_remove_warning(int id)
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{
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printk(KERN_WARNING
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"idr_remove called for id=%d which is not allocated.\n", id);
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dump_stack();
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}
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static void sub_remove(struct idr *idp, int shift, int id)
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{
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struct idr_layer *p = idp->top;
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struct idr_layer **pa[MAX_LEVEL];
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struct idr_layer ***paa = &pa[0];
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struct idr_layer *to_free;
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int n;
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*paa = NULL;
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*++paa = &idp->top;
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while ((shift > 0) && p) {
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n = (id >> shift) & IDR_MASK;
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__clear_bit(n, &p->bitmap);
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*++paa = &p->ary[n];
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p = p->ary[n];
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shift -= IDR_BITS;
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}
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n = id & IDR_MASK;
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if (likely(p != NULL && test_bit(n, &p->bitmap))){
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__clear_bit(n, &p->bitmap);
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rcu_assign_pointer(p->ary[n], NULL);
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to_free = NULL;
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while(*paa && ! --((**paa)->count)){
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if (to_free)
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free_layer(to_free);
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to_free = **paa;
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**paa-- = NULL;
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}
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if (!*paa)
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idp->layers = 0;
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if (to_free)
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free_layer(to_free);
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} else
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idr_remove_warning(id);
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}
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/**
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* idr_remove - remove the given id and free it's slot
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* @idp: idr handle
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* @id: unique key
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*/
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void idr_remove(struct idr *idp, int id)
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{
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struct idr_layer *p;
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struct idr_layer *to_free;
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/* Mask off upper bits we don't use for the search. */
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id &= MAX_ID_MASK;
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sub_remove(idp, (idp->layers - 1) * IDR_BITS, id);
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if (idp->top && idp->top->count == 1 && (idp->layers > 1) &&
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idp->top->ary[0]) {
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/*
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* Single child at leftmost slot: we can shrink the tree.
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* This level is not needed anymore since when layers are
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* inserted, they are inserted at the top of the existing
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* tree.
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*/
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to_free = idp->top;
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p = idp->top->ary[0];
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rcu_assign_pointer(idp->top, p);
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--idp->layers;
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to_free->bitmap = to_free->count = 0;
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free_layer(to_free);
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}
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while (idp->id_free_cnt >= IDR_FREE_MAX) {
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p = get_from_free_list(idp);
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/*
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* Note: we don't call the rcu callback here, since the only
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* layers that fall into the freelist are those that have been
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* preallocated.
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*/
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kmem_cache_free(idr_layer_cache, p);
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}
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return;
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}
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EXPORT_SYMBOL(idr_remove);
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/**
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* idr_remove_all - remove all ids from the given idr tree
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* @idp: idr handle
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*
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* idr_destroy() only frees up unused, cached idp_layers, but this
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* function will remove all id mappings and leave all idp_layers
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* unused.
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*
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* A typical clean-up sequence for objects stored in an idr tree, will
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* use idr_for_each() to free all objects, if necessay, then
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* idr_remove_all() to remove all ids, and idr_destroy() to free
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* up the cached idr_layers.
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*/
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void idr_remove_all(struct idr *idp)
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{
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int n, id, max;
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struct idr_layer *p;
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struct idr_layer *pa[MAX_LEVEL];
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struct idr_layer **paa = &pa[0];
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n = idp->layers * IDR_BITS;
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p = idp->top;
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max = 1 << n;
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id = 0;
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while (id < max) {
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while (n > IDR_BITS && p) {
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n -= IDR_BITS;
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*paa++ = p;
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p = p->ary[(id >> n) & IDR_MASK];
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}
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id += 1 << n;
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while (n < fls(id)) {
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if (p)
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free_layer(p);
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n += IDR_BITS;
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p = *--paa;
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}
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}
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rcu_assign_pointer(idp->top, NULL);
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idp->layers = 0;
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}
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EXPORT_SYMBOL(idr_remove_all);
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/**
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* idr_destroy - release all cached layers within an idr tree
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* idp: idr handle
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*/
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void idr_destroy(struct idr *idp)
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{
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while (idp->id_free_cnt) {
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struct idr_layer *p = get_from_free_list(idp);
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kmem_cache_free(idr_layer_cache, p);
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}
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}
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EXPORT_SYMBOL(idr_destroy);
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/**
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* idr_find - return pointer for given id
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* @idp: idr handle
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* @id: lookup key
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*
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* Return the pointer given the id it has been registered with. A %NULL
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* return indicates that @id is not valid or you passed %NULL in
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* idr_get_new().
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*
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* This function can be called under rcu_read_lock(), given that the leaf
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* pointers lifetimes are correctly managed.
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*/
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void *idr_find(struct idr *idp, int id)
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{
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int n;
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struct idr_layer *p;
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p = rcu_dereference(idp->top);
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if (!p)
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return NULL;
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n = (p->layer+1) * IDR_BITS;
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|
|
/* Mask off upper bits we don't use for the search. */
|
|
id &= MAX_ID_MASK;
|
|
|
|
if (id >= (1 << n))
|
|
return NULL;
|
|
BUG_ON(n == 0);
|
|
|
|
while (n > 0 && p) {
|
|
n -= IDR_BITS;
|
|
BUG_ON(n != p->layer*IDR_BITS);
|
|
p = rcu_dereference(p->ary[(id >> n) & IDR_MASK]);
|
|
}
|
|
return((void *)p);
|
|
}
|
|
EXPORT_SYMBOL(idr_find);
|
|
|
|
/**
|
|
* idr_for_each - iterate through all stored pointers
|
|
* @idp: idr handle
|
|
* @fn: function to be called for each pointer
|
|
* @data: data passed back to callback function
|
|
*
|
|
* Iterate over the pointers registered with the given idr. The
|
|
* callback function will be called for each pointer currently
|
|
* registered, passing the id, the pointer and the data pointer passed
|
|
* to this function. It is not safe to modify the idr tree while in
|
|
* the callback, so functions such as idr_get_new and idr_remove are
|
|
* not allowed.
|
|
*
|
|
* We check the return of @fn each time. If it returns anything other
|
|
* than 0, we break out and return that value.
|
|
*
|
|
* The caller must serialize idr_for_each() vs idr_get_new() and idr_remove().
|
|
*/
|
|
int idr_for_each(struct idr *idp,
|
|
int (*fn)(int id, void *p, void *data), void *data)
|
|
{
|
|
int n, id, max, error = 0;
|
|
struct idr_layer *p;
|
|
struct idr_layer *pa[MAX_LEVEL];
|
|
struct idr_layer **paa = &pa[0];
|
|
|
|
n = idp->layers * IDR_BITS;
|
|
p = rcu_dereference(idp->top);
|
|
max = 1 << n;
|
|
|
|
id = 0;
|
|
while (id < max) {
|
|
while (n > 0 && p) {
|
|
n -= IDR_BITS;
|
|
*paa++ = p;
|
|
p = rcu_dereference(p->ary[(id >> n) & IDR_MASK]);
|
|
}
|
|
|
|
if (p) {
|
|
error = fn(id, (void *)p, data);
|
|
if (error)
|
|
break;
|
|
}
|
|
|
|
id += 1 << n;
|
|
while (n < fls(id)) {
|
|
n += IDR_BITS;
|
|
p = *--paa;
|
|
}
|
|
}
|
|
|
|
return error;
|
|
}
|
|
EXPORT_SYMBOL(idr_for_each);
|
|
|
|
/**
|
|
* idr_replace - replace pointer for given id
|
|
* @idp: idr handle
|
|
* @ptr: pointer you want associated with the id
|
|
* @id: lookup key
|
|
*
|
|
* Replace the pointer registered with an id and return the old value.
|
|
* A -ENOENT return indicates that @id was not found.
|
|
* A -EINVAL return indicates that @id was not within valid constraints.
|
|
*
|
|
* The caller must serialize with writers.
|
|
*/
|
|
void *idr_replace(struct idr *idp, void *ptr, int id)
|
|
{
|
|
int n;
|
|
struct idr_layer *p, *old_p;
|
|
|
|
p = idp->top;
|
|
if (!p)
|
|
return ERR_PTR(-EINVAL);
|
|
|
|
n = (p->layer+1) * IDR_BITS;
|
|
|
|
id &= MAX_ID_MASK;
|
|
|
|
if (id >= (1 << n))
|
|
return ERR_PTR(-EINVAL);
|
|
|
|
n -= IDR_BITS;
|
|
while ((n > 0) && p) {
|
|
p = p->ary[(id >> n) & IDR_MASK];
|
|
n -= IDR_BITS;
|
|
}
|
|
|
|
n = id & IDR_MASK;
|
|
if (unlikely(p == NULL || !test_bit(n, &p->bitmap)))
|
|
return ERR_PTR(-ENOENT);
|
|
|
|
old_p = p->ary[n];
|
|
rcu_assign_pointer(p->ary[n], ptr);
|
|
|
|
return old_p;
|
|
}
|
|
EXPORT_SYMBOL(idr_replace);
|
|
|
|
static void idr_cache_ctor(void *idr_layer)
|
|
{
|
|
memset(idr_layer, 0, sizeof(struct idr_layer));
|
|
}
|
|
|
|
void __init idr_init_cache(void)
|
|
{
|
|
idr_layer_cache = kmem_cache_create("idr_layer_cache",
|
|
sizeof(struct idr_layer), 0, SLAB_PANIC,
|
|
idr_cache_ctor);
|
|
}
|
|
|
|
/**
|
|
* idr_init - initialize idr handle
|
|
* @idp: idr handle
|
|
*
|
|
* This function is use to set up the handle (@idp) that you will pass
|
|
* to the rest of the functions.
|
|
*/
|
|
void idr_init(struct idr *idp)
|
|
{
|
|
memset(idp, 0, sizeof(struct idr));
|
|
spin_lock_init(&idp->lock);
|
|
}
|
|
EXPORT_SYMBOL(idr_init);
|
|
|
|
|
|
/*
|
|
* IDA - IDR based ID allocator
|
|
*
|
|
* this is id allocator without id -> pointer translation. Memory
|
|
* usage is much lower than full blown idr because each id only
|
|
* occupies a bit. ida uses a custom leaf node which contains
|
|
* IDA_BITMAP_BITS slots.
|
|
*
|
|
* 2007-04-25 written by Tejun Heo <htejun@gmail.com>
|
|
*/
|
|
|
|
static void free_bitmap(struct ida *ida, struct ida_bitmap *bitmap)
|
|
{
|
|
unsigned long flags;
|
|
|
|
if (!ida->free_bitmap) {
|
|
spin_lock_irqsave(&ida->idr.lock, flags);
|
|
if (!ida->free_bitmap) {
|
|
ida->free_bitmap = bitmap;
|
|
bitmap = NULL;
|
|
}
|
|
spin_unlock_irqrestore(&ida->idr.lock, flags);
|
|
}
|
|
|
|
kfree(bitmap);
|
|
}
|
|
|
|
/**
|
|
* ida_pre_get - reserve resources for ida allocation
|
|
* @ida: ida handle
|
|
* @gfp_mask: memory allocation flag
|
|
*
|
|
* This function should be called prior to locking and calling the
|
|
* following function. It preallocates enough memory to satisfy the
|
|
* worst possible allocation.
|
|
*
|
|
* If the system is REALLY out of memory this function returns 0,
|
|
* otherwise 1.
|
|
*/
|
|
int ida_pre_get(struct ida *ida, gfp_t gfp_mask)
|
|
{
|
|
/* allocate idr_layers */
|
|
if (!idr_pre_get(&ida->idr, gfp_mask))
|
|
return 0;
|
|
|
|
/* allocate free_bitmap */
|
|
if (!ida->free_bitmap) {
|
|
struct ida_bitmap *bitmap;
|
|
|
|
bitmap = kmalloc(sizeof(struct ida_bitmap), gfp_mask);
|
|
if (!bitmap)
|
|
return 0;
|
|
|
|
free_bitmap(ida, bitmap);
|
|
}
|
|
|
|
return 1;
|
|
}
|
|
EXPORT_SYMBOL(ida_pre_get);
|
|
|
|
/**
|
|
* ida_get_new_above - allocate new ID above or equal to a start id
|
|
* @ida: ida handle
|
|
* @staring_id: id to start search at
|
|
* @p_id: pointer to the allocated handle
|
|
*
|
|
* Allocate new ID above or equal to @ida. It should be called with
|
|
* any required locks.
|
|
*
|
|
* If memory is required, it will return -EAGAIN, you should unlock
|
|
* and go back to the ida_pre_get() call. If the ida is full, it will
|
|
* return -ENOSPC.
|
|
*
|
|
* @p_id returns a value in the range 0 ... 0x7fffffff.
|
|
*/
|
|
int ida_get_new_above(struct ida *ida, int starting_id, int *p_id)
|
|
{
|
|
struct idr_layer *pa[MAX_LEVEL];
|
|
struct ida_bitmap *bitmap;
|
|
unsigned long flags;
|
|
int idr_id = starting_id / IDA_BITMAP_BITS;
|
|
int offset = starting_id % IDA_BITMAP_BITS;
|
|
int t, id;
|
|
|
|
restart:
|
|
/* get vacant slot */
|
|
t = idr_get_empty_slot(&ida->idr, idr_id, pa);
|
|
if (t < 0)
|
|
return _idr_rc_to_errno(t);
|
|
|
|
if (t * IDA_BITMAP_BITS >= MAX_ID_BIT)
|
|
return -ENOSPC;
|
|
|
|
if (t != idr_id)
|
|
offset = 0;
|
|
idr_id = t;
|
|
|
|
/* if bitmap isn't there, create a new one */
|
|
bitmap = (void *)pa[0]->ary[idr_id & IDR_MASK];
|
|
if (!bitmap) {
|
|
spin_lock_irqsave(&ida->idr.lock, flags);
|
|
bitmap = ida->free_bitmap;
|
|
ida->free_bitmap = NULL;
|
|
spin_unlock_irqrestore(&ida->idr.lock, flags);
|
|
|
|
if (!bitmap)
|
|
return -EAGAIN;
|
|
|
|
memset(bitmap, 0, sizeof(struct ida_bitmap));
|
|
rcu_assign_pointer(pa[0]->ary[idr_id & IDR_MASK],
|
|
(void *)bitmap);
|
|
pa[0]->count++;
|
|
}
|
|
|
|
/* lookup for empty slot */
|
|
t = find_next_zero_bit(bitmap->bitmap, IDA_BITMAP_BITS, offset);
|
|
if (t == IDA_BITMAP_BITS) {
|
|
/* no empty slot after offset, continue to the next chunk */
|
|
idr_id++;
|
|
offset = 0;
|
|
goto restart;
|
|
}
|
|
|
|
id = idr_id * IDA_BITMAP_BITS + t;
|
|
if (id >= MAX_ID_BIT)
|
|
return -ENOSPC;
|
|
|
|
__set_bit(t, bitmap->bitmap);
|
|
if (++bitmap->nr_busy == IDA_BITMAP_BITS)
|
|
idr_mark_full(pa, idr_id);
|
|
|
|
*p_id = id;
|
|
|
|
/* Each leaf node can handle nearly a thousand slots and the
|
|
* whole idea of ida is to have small memory foot print.
|
|
* Throw away extra resources one by one after each successful
|
|
* allocation.
|
|
*/
|
|
if (ida->idr.id_free_cnt || ida->free_bitmap) {
|
|
struct idr_layer *p = get_from_free_list(&ida->idr);
|
|
if (p)
|
|
kmem_cache_free(idr_layer_cache, p);
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(ida_get_new_above);
|
|
|
|
/**
|
|
* ida_get_new - allocate new ID
|
|
* @ida: idr handle
|
|
* @p_id: pointer to the allocated handle
|
|
*
|
|
* Allocate new ID. It should be called with any required locks.
|
|
*
|
|
* If memory is required, it will return -EAGAIN, you should unlock
|
|
* and go back to the idr_pre_get() call. If the idr is full, it will
|
|
* return -ENOSPC.
|
|
*
|
|
* @id returns a value in the range 0 ... 0x7fffffff.
|
|
*/
|
|
int ida_get_new(struct ida *ida, int *p_id)
|
|
{
|
|
return ida_get_new_above(ida, 0, p_id);
|
|
}
|
|
EXPORT_SYMBOL(ida_get_new);
|
|
|
|
/**
|
|
* ida_remove - remove the given ID
|
|
* @ida: ida handle
|
|
* @id: ID to free
|
|
*/
|
|
void ida_remove(struct ida *ida, int id)
|
|
{
|
|
struct idr_layer *p = ida->idr.top;
|
|
int shift = (ida->idr.layers - 1) * IDR_BITS;
|
|
int idr_id = id / IDA_BITMAP_BITS;
|
|
int offset = id % IDA_BITMAP_BITS;
|
|
int n;
|
|
struct ida_bitmap *bitmap;
|
|
|
|
/* clear full bits while looking up the leaf idr_layer */
|
|
while ((shift > 0) && p) {
|
|
n = (idr_id >> shift) & IDR_MASK;
|
|
__clear_bit(n, &p->bitmap);
|
|
p = p->ary[n];
|
|
shift -= IDR_BITS;
|
|
}
|
|
|
|
if (p == NULL)
|
|
goto err;
|
|
|
|
n = idr_id & IDR_MASK;
|
|
__clear_bit(n, &p->bitmap);
|
|
|
|
bitmap = (void *)p->ary[n];
|
|
if (!test_bit(offset, bitmap->bitmap))
|
|
goto err;
|
|
|
|
/* update bitmap and remove it if empty */
|
|
__clear_bit(offset, bitmap->bitmap);
|
|
if (--bitmap->nr_busy == 0) {
|
|
__set_bit(n, &p->bitmap); /* to please idr_remove() */
|
|
idr_remove(&ida->idr, idr_id);
|
|
free_bitmap(ida, bitmap);
|
|
}
|
|
|
|
return;
|
|
|
|
err:
|
|
printk(KERN_WARNING
|
|
"ida_remove called for id=%d which is not allocated.\n", id);
|
|
}
|
|
EXPORT_SYMBOL(ida_remove);
|
|
|
|
/**
|
|
* ida_destroy - release all cached layers within an ida tree
|
|
* ida: ida handle
|
|
*/
|
|
void ida_destroy(struct ida *ida)
|
|
{
|
|
idr_destroy(&ida->idr);
|
|
kfree(ida->free_bitmap);
|
|
}
|
|
EXPORT_SYMBOL(ida_destroy);
|
|
|
|
/**
|
|
* ida_init - initialize ida handle
|
|
* @ida: ida handle
|
|
*
|
|
* This function is use to set up the handle (@ida) that you will pass
|
|
* to the rest of the functions.
|
|
*/
|
|
void ida_init(struct ida *ida)
|
|
{
|
|
memset(ida, 0, sizeof(struct ida));
|
|
idr_init(&ida->idr);
|
|
|
|
}
|
|
EXPORT_SYMBOL(ida_init);
|