/* * 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 MAX_IDR_FREE) 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/export.h> #endif #include <linux/err.h> #include <linux/string.h> #include <linux/idr.h> #include <linux/spinlock.h> #include <linux/percpu.h> #include <linux/hardirq.h> #define MAX_IDR_SHIFT (sizeof(int) * 8 - 1) #define MAX_IDR_BIT (1U << MAX_IDR_SHIFT) /* Leave the possibility of an incomplete final layer */ #define MAX_IDR_LEVEL ((MAX_IDR_SHIFT + IDR_BITS - 1) / IDR_BITS) /* Number of id_layer structs to leave in free list */ #define MAX_IDR_FREE (MAX_IDR_LEVEL * 2) static struct kmem_cache *idr_layer_cache; static DEFINE_PER_CPU(struct idr_layer *, idr_preload_head); static DEFINE_PER_CPU(int, idr_preload_cnt); static DEFINE_SPINLOCK(simple_ida_lock); /* the maximum ID which can be allocated given idr->layers */ static int idr_max(int layers) { int bits = min_t(int, layers * IDR_BITS, MAX_IDR_SHIFT); return (1 << bits) - 1; } /* * Prefix mask for an idr_layer at @layer. For layer 0, the prefix mask is * all bits except for the lower IDR_BITS. For layer 1, 2 * IDR_BITS, and * so on. */ static int idr_layer_prefix_mask(int layer) { return ~idr_max(layer + 1); } 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); } /** * idr_layer_alloc - allocate a new idr_layer * @gfp_mask: allocation mask * @layer_idr: optional idr to allocate from * * If @layer_idr is %NULL, directly allocate one using @gfp_mask or fetch * one from the per-cpu preload buffer. If @layer_idr is not %NULL, fetch * an idr_layer from @idr->id_free. * * @layer_idr is to maintain backward compatibility with the old alloc * interface - idr_pre_get() and idr_get_new*() - and will be removed * together with per-pool preload buffer. */ static struct idr_layer *idr_layer_alloc(gfp_t gfp_mask, struct idr *layer_idr) { struct idr_layer *new; /* this is the old path, bypass to get_from_free_list() */ if (layer_idr) return get_from_free_list(layer_idr); /* * Try to allocate directly from kmem_cache. We want to try this * before preload buffer; otherwise, non-preloading idr_alloc() * users will end up taking advantage of preloading ones. As the * following is allowed to fail for preloaded cases, suppress * warning this time. */ new = kmem_cache_zalloc(idr_layer_cache, gfp_mask | __GFP_NOWARN); if (new) return new; /* * Try to fetch one from the per-cpu preload buffer if in process * context. See idr_preload() for details. */ if (!in_interrupt()) { preempt_disable(); new = __this_cpu_read(idr_preload_head); if (new) { __this_cpu_write(idr_preload_head, new->ary[0]); __this_cpu_dec(idr_preload_cnt); new->ary[0] = NULL; } preempt_enable(); if (new) return new; } /* * Both failed. Try kmem_cache again w/o adding __GFP_NOWARN so * that memory allocation failure warning is printed as intended. */ return kmem_cache_zalloc(idr_layer_cache, gfp_mask); } 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 *idr, struct idr_layer *p) { if (idr->hint && idr->hint == p) RCU_INIT_POINTER(idr->hint, NULL); 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 (bitmap_full(p->bitmap, IDR_SIZE)) { if (!(p = pa[++l])) break; id = id >> IDR_BITS; __set_bit((id & IDR_MASK), p->bitmap); } } int __idr_pre_get(struct idr *idp, gfp_t gfp_mask) { while (idp->id_free_cnt < MAX_IDR_FREE) { 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); /** * sub_alloc - try to allocate an id without growing the tree depth * @idp: idr handle * @starting_id: id to start search at * @pa: idr_layer[MAX_IDR_LEVEL] used as backtrack buffer * @gfp_mask: allocation mask for idr_layer_alloc() * @layer_idr: optional idr passed to idr_layer_alloc() * * Allocate an id in range [@starting_id, INT_MAX] from @idp without * growing its depth. Returns * * the allocated id >= 0 if successful, * -EAGAIN if the tree needs to grow for allocation to succeed, * -ENOSPC if the id space is exhausted, * -ENOMEM if more idr_layers need to be allocated. */ static int sub_alloc(struct idr *idp, int *starting_id, struct idr_layer **pa, gfp_t gfp_mask, struct idr *layer_idr) { int n, m, sh; struct idr_layer *p, *new; int l, id, oid; 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; m = find_next_zero_bit(p->bitmap, 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 (id >= 1 << (idp->layers * IDR_BITS)) { *starting_id = id; return -EAGAIN; } p = pa[l]; BUG_ON(!p); /* 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_IDR_BIT) || (id < 0)) return -ENOSPC; if (l == 0) break; /* * Create the layer below if it is missing. */ if (!p->ary[m]) { new = idr_layer_alloc(gfp_mask, layer_idr); if (!new) return -ENOMEM; new->layer = l-1; new->prefix = id & idr_layer_prefix_mask(new->layer); 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, gfp_t gfp_mask, struct idr *layer_idr) { 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 = idr_layer_alloc(gfp_mask, layer_idr))) return -ENOMEM; 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 (id > idr_max(layers)) { 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++; WARN_ON_ONCE(p->prefix); continue; } if (!(new = idr_layer_alloc(gfp_mask, layer_idr))) { /* * 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->count = 0; bitmap_clear(new->bitmap, 0, IDR_SIZE); __move_to_free_list(idp, new); } spin_unlock_irqrestore(&idp->lock, flags); return -ENOMEM; } new->ary[0] = p; new->count = 1; new->layer = layers-1; new->prefix = id & idr_layer_prefix_mask(new->layer); if (bitmap_full(p->bitmap, IDR_SIZE)) __set_bit(0, new->bitmap); p = new; } rcu_assign_pointer(idp->top, p); idp->layers = layers; v = sub_alloc(idp, &id, pa, gfp_mask, layer_idr); if (v == -EAGAIN) goto build_up; return(v); } /* * @id and @pa are from a successful allocation from idr_get_empty_slot(). * Install the user pointer @ptr and mark the slot full. */ static void idr_fill_slot(struct idr *idr, void *ptr, int id, struct idr_layer **pa) { /* update hint used for lookup, cleared from free_layer() */ rcu_assign_pointer(idr->hint, pa[0]); rcu_assign_pointer(pa[0]->ary[id & IDR_MASK], (struct idr_layer *)ptr); pa[0]->count++; idr_mark_full(pa, id); } int __idr_get_new_above(struct idr *idp, void *ptr, int starting_id, int *id) { struct idr_layer *pa[MAX_IDR_LEVEL + 1]; int rv; rv = idr_get_empty_slot(idp, starting_id, pa, 0, idp); if (rv < 0) return rv == -ENOMEM ? -EAGAIN : rv; idr_fill_slot(idp, ptr, rv, pa); *id = rv; return 0; } EXPORT_SYMBOL(__idr_get_new_above); /** * idr_preload - preload for idr_alloc() * @gfp_mask: allocation mask to use for preloading * * Preload per-cpu layer buffer for idr_alloc(). Can only be used from * process context and each idr_preload() invocation should be matched with * idr_preload_end(). Note that preemption is disabled while preloaded. * * The first idr_alloc() in the preloaded section can be treated as if it * were invoked with @gfp_mask used for preloading. This allows using more * permissive allocation masks for idrs protected by spinlocks. * * For example, if idr_alloc() below fails, the failure can be treated as * if idr_alloc() were called with GFP_KERNEL rather than GFP_NOWAIT. * * idr_preload(GFP_KERNEL); * spin_lock(lock); * * id = idr_alloc(idr, ptr, start, end, GFP_NOWAIT); * * spin_unlock(lock); * idr_preload_end(); * if (id < 0) * error; */ void idr_preload(gfp_t gfp_mask) { /* * Consuming preload buffer from non-process context breaks preload * allocation guarantee. Disallow usage from those contexts. */ WARN_ON_ONCE(in_interrupt()); might_sleep_if(gfp_mask & __GFP_WAIT); preempt_disable(); /* * idr_alloc() is likely to succeed w/o full idr_layer buffer and * return value from idr_alloc() needs to be checked for failure * anyway. Silently give up if allocation fails. The caller can * treat failures from idr_alloc() as if idr_alloc() were called * with @gfp_mask which should be enough. */ while (__this_cpu_read(idr_preload_cnt) < MAX_IDR_FREE) { struct idr_layer *new; preempt_enable(); new = kmem_cache_zalloc(idr_layer_cache, gfp_mask); preempt_disable(); if (!new) break; /* link the new one to per-cpu preload list */ new->ary[0] = __this_cpu_read(idr_preload_head); __this_cpu_write(idr_preload_head, new); __this_cpu_inc(idr_preload_cnt); } } EXPORT_SYMBOL(idr_preload); /** * idr_alloc - allocate new idr entry * @idr: the (initialized) idr * @ptr: pointer to be associated with the new id * @start: the minimum id (inclusive) * @end: the maximum id (exclusive, <= 0 for max) * @gfp_mask: memory allocation flags * * Allocate an id in [start, end) and associate it with @ptr. If no ID is * available in the specified range, returns -ENOSPC. On memory allocation * failure, returns -ENOMEM. * * Note that @end is treated as max when <= 0. This is to always allow * using @start + N as @end as long as N is inside integer range. * * The user is responsible for exclusively synchronizing all operations * which may modify @idr. However, read-only accesses such as idr_find() * or iteration can be performed under RCU read lock provided the user * destroys @ptr in RCU-safe way after removal from idr. */ int idr_alloc(struct idr *idr, void *ptr, int start, int end, gfp_t gfp_mask) { int max = end > 0 ? end - 1 : INT_MAX; /* inclusive upper limit */ struct idr_layer *pa[MAX_IDR_LEVEL + 1]; int id; might_sleep_if(gfp_mask & __GFP_WAIT); /* sanity checks */ if (WARN_ON_ONCE(start < 0)) return -EINVAL; if (unlikely(max < start)) return -ENOSPC; /* allocate id */ id = idr_get_empty_slot(idr, start, pa, gfp_mask, NULL); if (unlikely(id < 0)) return id; if (unlikely(id > max)) return -ENOSPC; idr_fill_slot(idr, ptr, id, pa); return id; } EXPORT_SYMBOL_GPL(idr_alloc); /** * idr_alloc_cyclic - allocate new idr entry in a cyclical fashion * @idr: the (initialized) idr * @ptr: pointer to be associated with the new id * @start: the minimum id (inclusive) * @end: the maximum id (exclusive, <= 0 for max) * @gfp_mask: memory allocation flags * * Essentially the same as idr_alloc, but prefers to allocate progressively * higher ids if it can. If the "cur" counter wraps, then it will start again * at the "start" end of the range and allocate one that has already been used. */ int idr_alloc_cyclic(struct idr *idr, void *ptr, int start, int end, gfp_t gfp_mask) { int id; id = idr_alloc(idr, ptr, max(start, idr->cur), end, gfp_mask); if (id == -ENOSPC) id = idr_alloc(idr, ptr, start, end, gfp_mask); if (likely(id >= 0)) idr->cur = id + 1; return id; } EXPORT_SYMBOL(idr_alloc_cyclic); 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_IDR_LEVEL + 1]; 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(idp, to_free); to_free = **paa; **paa-- = NULL; } if (!*paa) idp->layers = 0; if (to_free) free_layer(idp, to_free); } else idr_remove_warning(id); } /** * idr_remove - remove the given id and free its slot * @idp: idr handle * @id: unique key */ void idr_remove(struct idr *idp, int id) { struct idr_layer *p; struct idr_layer *to_free; if (id < 0) return; 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->count = 0; bitmap_clear(to_free->bitmap, 0, IDR_SIZE); free_layer(idp, to_free); } while (idp->id_free_cnt >= MAX_IDR_FREE) { 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); void __idr_remove_all(struct idr *idp) { int n, id, max; int bt_mask; struct idr_layer *p; struct idr_layer *pa[MAX_IDR_LEVEL + 1]; struct idr_layer **paa = &pa[0]; n = idp->layers * IDR_BITS; p = idp->top; rcu_assign_pointer(idp->top, NULL); max = idr_max(idp->layers); id = 0; while (id >= 0 && id <= max) { while (n > IDR_BITS && p) { n -= IDR_BITS; *paa++ = p; p = p->ary[(id >> n) & IDR_MASK]; } bt_mask = id; id += 1 << n; /* Get the highest bit that the above add changed from 0->1. */ while (n < fls(id ^ bt_mask)) { if (p) free_layer(idp, p); n += IDR_BITS; p = *--paa; } } idp->layers = 0; } EXPORT_SYMBOL(__idr_remove_all); /** * idr_destroy - release all cached layers within an idr tree * @idp: idr handle * * Free all id mappings and all idp_layers. After this function, @idp is * completely unused and can be freed / recycled. The caller is * responsible for ensuring that no one else accesses @idp during or after * idr_destroy(). * * 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_destroy() to * free up the id mappings and cached idr_layers. */ void idr_destroy(struct idr *idp) { __idr_remove_all(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); void *idr_find_slowpath(struct idr *idp, int id) { int n; struct idr_layer *p; if (id < 0) return NULL; p = rcu_dereference_raw(idp->top); if (!p) return NULL; n = (p->layer+1) * IDR_BITS; if (id > idr_max(p->layer + 1)) return NULL; BUG_ON(n == 0); while (n > 0 && p) { n -= IDR_BITS; BUG_ON(n != p->layer*IDR_BITS); p = rcu_dereference_raw(p->ary[(id >> n) & IDR_MASK]); } return((void *)p); } EXPORT_SYMBOL(idr_find_slowpath); /** * 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_IDR_LEVEL + 1]; struct idr_layer **paa = &pa[0]; n = idp->layers * IDR_BITS; p = rcu_dereference_raw(idp->top); max = idr_max(idp->layers); id = 0; while (id >= 0 && id <= max) { while (n > 0 && p) { n -= IDR_BITS; *paa++ = p; p = rcu_dereference_raw(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_get_next - lookup next object of id to given id. * @idp: idr handle * @nextidp: pointer to lookup key * * Returns pointer to registered object with id, which is next number to * given id. After being looked up, *@nextidp will be updated for the next * iteration. * * This function can be called under rcu_read_lock(), given that the leaf * pointers lifetimes are correctly managed. */ void *idr_get_next(struct idr *idp, int *nextidp) { struct idr_layer *p, *pa[MAX_IDR_LEVEL + 1]; struct idr_layer **paa = &pa[0]; int id = *nextidp; int n, max; /* find first ent */ p = rcu_dereference_raw(idp->top); if (!p) return NULL; n = (p->layer + 1) * IDR_BITS; max = idr_max(p->layer + 1); while (id >= 0 && id <= max) { while (n > 0 && p) { n -= IDR_BITS; *paa++ = p; p = rcu_dereference_raw(p->ary[(id >> n) & IDR_MASK]); } if (p) { *nextidp = id; return p; } /* * Proceed to the next layer at the current level. Unlike * idr_for_each(), @id isn't guaranteed to be aligned to * layer boundary at this point and adding 1 << n may * incorrectly skip IDs. Make sure we jump to the * beginning of the next layer using round_up(). */ id = round_up(id + 1, 1 << n); while (n < fls(id)) { n += IDR_BITS; p = *--paa; } } return NULL; } EXPORT_SYMBOL(idr_get_next); /** * 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; if (id < 0) return ERR_PTR(-EINVAL); p = idp->top; if (!p) return ERR_PTR(-EINVAL); n = (p->layer+1) * IDR_BITS; 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); /** * DOC: IDA description * 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 * @starting_id: id to start search at * @p_id: pointer to the allocated handle * * Allocate new ID above or equal to @starting_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 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_IDR_LEVEL + 1]; 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, 0, &ida->idr); if (t < 0) return t == -ENOMEM ? -EAGAIN : t; if (t * IDA_BITMAP_BITS >= MAX_IDR_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_IDR_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_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_simple_get - get a new id. * @ida: the (initialized) ida. * @start: the minimum id (inclusive, < 0x8000000) * @end: the maximum id (exclusive, < 0x8000000 or 0) * @gfp_mask: memory allocation flags * * Allocates an id in the range start <= id < end, or returns -ENOSPC. * On memory allocation failure, returns -ENOMEM. * * Use ida_simple_remove() to get rid of an id. */ int ida_simple_get(struct ida *ida, unsigned int start, unsigned int end, gfp_t gfp_mask) { int ret, id; unsigned int max; unsigned long flags; BUG_ON((int)start < 0); BUG_ON((int)end < 0); if (end == 0) max = 0x80000000; else { BUG_ON(end < start); max = end - 1; } again: if (!ida_pre_get(ida, gfp_mask)) return -ENOMEM; spin_lock_irqsave(&simple_ida_lock, flags); ret = ida_get_new_above(ida, start, &id); if (!ret) { if (id > max) { ida_remove(ida, id); ret = -ENOSPC; } else { ret = id; } } spin_unlock_irqrestore(&simple_ida_lock, flags); if (unlikely(ret == -EAGAIN)) goto again; return ret; } EXPORT_SYMBOL(ida_simple_get); /** * ida_simple_remove - remove an allocated id. * @ida: the (initialized) ida. * @id: the id returned by ida_simple_get. */ void ida_simple_remove(struct ida *ida, unsigned int id) { unsigned long flags; BUG_ON((int)id < 0); spin_lock_irqsave(&simple_ida_lock, flags); ida_remove(ida, id); spin_unlock_irqrestore(&simple_ida_lock, flags); } EXPORT_SYMBOL(ida_simple_remove); /** * 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);