/* * 2002-10-18 written by Jim Houston jim.houston@ccur.com * Copyright (C) 2002 by Concurrent Computer Corporation * Distributed under the GNU GPL license version 2. * * Modified by George Anzinger to reuse immediately and to use * find bit instructions. Also removed _irq on spinlocks. * * Modified by Nadia Derbey to make it RCU safe. * * Small id to pointer translation service. * * It uses a radix tree like structure as a sparse array indexed * by the id to obtain the pointer. The bitmap makes allocating * a new id quick. * * You call it to allocate an id (an int) an associate with that id a * pointer or what ever, we treat it as a (void *). You can pass this * id to a user for him to pass back at a later time. You then pass * that id to this code and it returns your pointer. * You can release ids at any time. When all ids are released, most of * the memory is returned (we keep IDR_FREE_MAX) in a local pool so we * don't need to go to the memory "store" during an id allocate, just * so you don't need to be too concerned about locking and conflicts * with the slab allocator. */ #ifndef TEST // to test in user space... #include <linux/slab.h> #include <linux/init.h> #include <linux/module.h> #endif #include <linux/err.h> #include <linux/string.h> #include <linux/idr.h> static struct kmem_cache *idr_layer_cache; static struct idr_layer *get_from_free_list(struct idr *idp) { struct idr_layer *p; unsigned long flags; spin_lock_irqsave(&idp->lock, flags); if ((p = idp->id_free)) { idp->id_free = p->ary[0]; idp->id_free_cnt--; p->ary[0] = NULL; } spin_unlock_irqrestore(&idp->lock, flags); return(p); } static void idr_layer_rcu_free(struct rcu_head *head) { struct idr_layer *layer; layer = container_of(head, struct idr_layer, rcu_head); kmem_cache_free(idr_layer_cache, layer); } static inline void free_layer(struct idr_layer *p) { call_rcu(&p->rcu_head, idr_layer_rcu_free); } /* only called when idp->lock is held */ static void __move_to_free_list(struct idr *idp, struct idr_layer *p) { p->ary[0] = idp->id_free; idp->id_free = p; idp->id_free_cnt++; } static void move_to_free_list(struct idr *idp, struct idr_layer *p) { unsigned long flags; /* * Depends on the return element being zeroed. */ spin_lock_irqsave(&idp->lock, flags); __move_to_free_list(idp, p); spin_unlock_irqrestore(&idp->lock, flags); } static void idr_mark_full(struct idr_layer **pa, int id) { struct idr_layer *p = pa[0]; int l = 0; __set_bit(id & IDR_MASK, &p->bitmap); /* * If this layer is full mark the bit in the layer above to * show that this part of the radix tree is full. This may * complete the layer above and require walking up the radix * tree. */ while (p->bitmap == IDR_FULL) { if (!(p = pa[++l])) break; id = id >> IDR_BITS; __set_bit((id & IDR_MASK), &p->bitmap); } } /** * idr_pre_get - reserver resources for idr allocation * @idp: idr handle * @gfp_mask: memory allocation flags * * This function should be called prior to locking and calling the * idr_get_new* functions. 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 idr_pre_get(struct idr *idp, gfp_t gfp_mask) { while (idp->id_free_cnt < IDR_FREE_MAX) { struct idr_layer *new; new = kmem_cache_zalloc(idr_layer_cache, gfp_mask); if (new == NULL) return (0); move_to_free_list(idp, new); } return 1; } EXPORT_SYMBOL(idr_pre_get); static int sub_alloc(struct idr *idp, int *starting_id, struct idr_layer **pa) { int n, m, sh; struct idr_layer *p, *new; int l, id, oid; unsigned long bm; id = *starting_id; restart: p = idp->top; l = idp->layers; pa[l--] = NULL; while (1) { /* * We run around this while until we reach the leaf node... */ n = (id >> (IDR_BITS*l)) & IDR_MASK; bm = ~p->bitmap; m = find_next_bit(&bm, IDR_SIZE, n); if (m == IDR_SIZE) { /* no space available go back to previous layer. */ l++; oid = id; id = (id | ((1 << (IDR_BITS * l)) - 1)) + 1; /* if already at the top layer, we need to grow */ if (!(p = pa[l])) { *starting_id = id; return IDR_NEED_TO_GROW; } /* If we need to go up one layer, continue the * loop; otherwise, restart from the top. */ sh = IDR_BITS * (l + 1); if (oid >> sh == id >> sh) continue; else goto restart; } if (m != n) { sh = IDR_BITS*l; id = ((id >> sh) ^ n ^ m) << sh; } if ((id >= MAX_ID_BIT) || (id < 0)) return IDR_NOMORE_SPACE; if (l == 0) break; /* * Create the layer below if it is missing. */ if (!p->ary[m]) { new = get_from_free_list(idp); if (!new) return -1; new->layer = l-1; rcu_assign_pointer(p->ary[m], new); p->count++; } pa[l--] = p; p = p->ary[m]; } pa[l] = p; return id; } static int idr_get_empty_slot(struct idr *idp, int starting_id, struct idr_layer **pa) { struct idr_layer *p, *new; int layers, v, id; unsigned long flags; id = starting_id; build_up: p = idp->top; layers = idp->layers; if (unlikely(!p)) { if (!(p = get_from_free_list(idp))) return -1; p->layer = 0; layers = 1; } /* * Add a new layer to the top of the tree if the requested * id is larger than the currently allocated space. */ while ((layers < (MAX_LEVEL - 1)) && (id >= (1 << (layers*IDR_BITS)))) { layers++; if (!p->count) { /* special case: if the tree is currently empty, * then we grow the tree by moving the top node * upwards. */ p->layer++; continue; } if (!(new = get_from_free_list(idp))) { /* * The allocation failed. If we built part of * the structure tear it down. */ spin_lock_irqsave(&idp->lock, flags); for (new = p; p && p != idp->top; new = p) { p = p->ary[0]; new->ary[0] = NULL; new->bitmap = new->count = 0; __move_to_free_list(idp, new); } spin_unlock_irqrestore(&idp->lock, flags); return -1; } new->ary[0] = p; new->count = 1; new->layer = layers-1; if (p->bitmap == IDR_FULL) __set_bit(0, &new->bitmap); p = new; } rcu_assign_pointer(idp->top, p); idp->layers = layers; v = sub_alloc(idp, &id, pa); if (v == IDR_NEED_TO_GROW) goto build_up; return(v); } static int idr_get_new_above_int(struct idr *idp, void *ptr, int starting_id) { struct idr_layer *pa[MAX_LEVEL]; int id; id = idr_get_empty_slot(idp, starting_id, pa); if (id >= 0) { /* * Successfully found an empty slot. Install the user * pointer and mark the slot full. */ rcu_assign_pointer(pa[0]->ary[id & IDR_MASK], (struct idr_layer *)ptr); pa[0]->count++; idr_mark_full(pa, id); } return id; } /** * idr_get_new_above - allocate new idr entry above or equal to a start id * @idp: idr handle * @ptr: pointer you want associated with the ide * @start_id: id to start search at * @id: pointer to the allocated handle * * This is the allocate id function. 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 @starting_id ... 0x7fffffff */ int idr_get_new_above(struct idr *idp, void *ptr, int starting_id, int *id) { int rv; rv = idr_get_new_above_int(idp, ptr, starting_id); /* * This is a cheap hack until the IDR code can be fixed to * return proper error values. */ if (rv < 0) return _idr_rc_to_errno(rv); *id = rv; return 0; } EXPORT_SYMBOL(idr_get_new_above); /** * idr_get_new - allocate new idr entry * @idp: idr handle * @ptr: pointer you want associated with the ide * @id: pointer to the allocated handle * * This is the allocate id function. 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 idr_get_new(struct idr *idp, void *ptr, int *id) { int rv; rv = idr_get_new_above_int(idp, ptr, 0); /* * This is a cheap hack until the IDR code can be fixed to * return proper error values. */ if (rv < 0) return _idr_rc_to_errno(rv); *id = rv; return 0; } EXPORT_SYMBOL(idr_get_new); static void idr_remove_warning(int id) { printk(KERN_WARNING "idr_remove called for id=%d which is not allocated.\n", id); dump_stack(); } static void sub_remove(struct idr *idp, int shift, int id) { struct idr_layer *p = idp->top; struct idr_layer **pa[MAX_LEVEL]; struct idr_layer ***paa = &pa[0]; struct idr_layer *to_free; int n; *paa = NULL; *++paa = &idp->top; while ((shift > 0) && p) { n = (id >> shift) & IDR_MASK; __clear_bit(n, &p->bitmap); *++paa = &p->ary[n]; p = p->ary[n]; shift -= IDR_BITS; } n = id & IDR_MASK; if (likely(p != NULL && test_bit(n, &p->bitmap))){ __clear_bit(n, &p->bitmap); rcu_assign_pointer(p->ary[n], NULL); to_free = NULL; while(*paa && ! --((**paa)->count)){ if (to_free) free_layer(to_free); to_free = **paa; **paa-- = NULL; } if (!*paa) idp->layers = 0; if (to_free) free_layer(to_free); } else idr_remove_warning(id); } /** * idr_remove - remove the given id and free it's slot * @idp: idr handle * @id: unique key */ void idr_remove(struct idr *idp, int id) { struct idr_layer *p; struct idr_layer *to_free; /* Mask off upper bits we don't use for the search. */ id &= MAX_ID_MASK; sub_remove(idp, (idp->layers - 1) * IDR_BITS, id); if (idp->top && idp->top->count == 1 && (idp->layers > 1) && idp->top->ary[0]) { /* * Single child at leftmost slot: we can shrink the tree. * This level is not needed anymore since when layers are * inserted, they are inserted at the top of the existing * tree. */ to_free = idp->top; p = idp->top->ary[0]; rcu_assign_pointer(idp->top, p); --idp->layers; to_free->bitmap = to_free->count = 0; free_layer(to_free); } while (idp->id_free_cnt >= IDR_FREE_MAX) { p = get_from_free_list(idp); /* * Note: we don't call the rcu callback here, since the only * layers that fall into the freelist are those that have been * preallocated. */ kmem_cache_free(idr_layer_cache, p); } return; } EXPORT_SYMBOL(idr_remove); /** * idr_remove_all - remove all ids from the given idr tree * @idp: idr handle * * idr_destroy() only frees up unused, cached idp_layers, but this * function will remove all id mappings and leave all idp_layers * unused. * * A typical clean-up sequence for objects stored in an idr tree, will * use idr_for_each() to free all objects, if necessay, then * idr_remove_all() to remove all ids, and idr_destroy() to free * up the cached idr_layers. */ void idr_remove_all(struct idr *idp) { int n, id, max; struct idr_layer *p; struct idr_layer *pa[MAX_LEVEL]; struct idr_layer **paa = &pa[0]; n = idp->layers * IDR_BITS; p = idp->top; max = 1 << n; id = 0; while (id < max) { while (n > IDR_BITS && p) { n -= IDR_BITS; *paa++ = p; p = p->ary[(id >> n) & IDR_MASK]; } id += 1 << n; while (n < fls(id)) { if (p) free_layer(p); n += IDR_BITS; p = *--paa; } } rcu_assign_pointer(idp->top, NULL); idp->layers = 0; } EXPORT_SYMBOL(idr_remove_all); /** * idr_destroy - release all cached layers within an idr tree * idp: idr handle */ void idr_destroy(struct idr *idp) { while (idp->id_free_cnt) { struct idr_layer *p = get_from_free_list(idp); kmem_cache_free(idr_layer_cache, p); } } EXPORT_SYMBOL(idr_destroy); /** * idr_find - return pointer for given id * @idp: idr handle * @id: lookup key * * Return the pointer given the id it has been registered with. A %NULL * return indicates that @id is not valid or you passed %NULL in * idr_get_new(). * * This function can be called under rcu_read_lock(), given that the leaf * pointers lifetimes are correctly managed. */ void *idr_find(struct idr *idp, int id) { int n; struct idr_layer *p; p = rcu_dereference(idp->top); if (!p) return NULL; n = (p->layer+1) * IDR_BITS; /* 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); void __init idr_init_cache(void) { idr_layer_cache = kmem_cache_create("idr_layer_cache", sizeof(struct idr_layer), 0, SLAB_PANIC, NULL); } /** * 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 @starting_id ... 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);