10a835c4fSMatthew Wilcox #include <linux/bitmap.h> 2460488c5SMatthew Wilcox #include <linux/bug.h> 38bc3bcc9SPaul Gortmaker #include <linux/export.h> 41da177e4SLinus Torvalds #include <linux/idr.h> 50a835c4fSMatthew Wilcox #include <linux/slab.h> 688eca020SRusty Russell #include <linux/spinlock.h> 7b94078e6SMatthew Wilcox #include <linux/xarray.h> 81da177e4SLinus Torvalds 9e096f6a7SMatthew Wilcox /** 10e096f6a7SMatthew Wilcox * idr_alloc_u32() - Allocate an ID. 11e096f6a7SMatthew Wilcox * @idr: IDR handle. 12e096f6a7SMatthew Wilcox * @ptr: Pointer to be associated with the new ID. 13e096f6a7SMatthew Wilcox * @nextid: Pointer to an ID. 14e096f6a7SMatthew Wilcox * @max: The maximum ID to allocate (inclusive). 15e096f6a7SMatthew Wilcox * @gfp: Memory allocation flags. 16e096f6a7SMatthew Wilcox * 17e096f6a7SMatthew Wilcox * Allocates an unused ID in the range specified by @nextid and @max. 18e096f6a7SMatthew Wilcox * Note that @max is inclusive whereas the @end parameter to idr_alloc() 19460488c5SMatthew Wilcox * is exclusive. The new ID is assigned to @nextid before the pointer 20460488c5SMatthew Wilcox * is inserted into the IDR, so if @nextid points into the object pointed 21460488c5SMatthew Wilcox * to by @ptr, a concurrent lookup will not find an uninitialised ID. 22e096f6a7SMatthew Wilcox * 23e096f6a7SMatthew Wilcox * The caller should provide their own locking to ensure that two 24e096f6a7SMatthew Wilcox * concurrent modifications to the IDR are not possible. Read-only 25e096f6a7SMatthew Wilcox * accesses to the IDR may be done under the RCU read lock or may 26e096f6a7SMatthew Wilcox * exclude simultaneous writers. 27e096f6a7SMatthew Wilcox * 28e096f6a7SMatthew Wilcox * Return: 0 if an ID was allocated, -ENOMEM if memory allocation failed, 29e096f6a7SMatthew Wilcox * or -ENOSPC if no free IDs could be found. If an error occurred, 30e096f6a7SMatthew Wilcox * @nextid is unchanged. 31e096f6a7SMatthew Wilcox */ 32e096f6a7SMatthew Wilcox int idr_alloc_u32(struct idr *idr, void *ptr, u32 *nextid, 33e096f6a7SMatthew Wilcox unsigned long max, gfp_t gfp) 34e096f6a7SMatthew Wilcox { 350a835c4fSMatthew Wilcox struct radix_tree_iter iter; 36388f79fdSChris Mi void __rcu **slot; 374b0ad076SMatthew Wilcox unsigned int base = idr->idr_base; 384b0ad076SMatthew Wilcox unsigned int id = *nextid; 39d5c7409fSTejun Heo 40f8d5d0ccSMatthew Wilcox if (WARN_ON_ONCE(!(idr->idr_rt.xa_flags & ROOT_IS_IDR))) 41f8d5d0ccSMatthew Wilcox idr->idr_rt.xa_flags |= IDR_RT_MARKER; 42d5c7409fSTejun Heo 436ce711f2SMatthew Wilcox id = (id < base) ? 0 : id - base; 446ce711f2SMatthew Wilcox radix_tree_iter_init(&iter, id); 456ce711f2SMatthew Wilcox slot = idr_get_free(&idr->idr_rt, &iter, gfp, max - base); 460a835c4fSMatthew Wilcox if (IS_ERR(slot)) 470a835c4fSMatthew Wilcox return PTR_ERR(slot); 48d5c7409fSTejun Heo 496ce711f2SMatthew Wilcox *nextid = iter.index + base; 50460488c5SMatthew Wilcox /* there is a memory barrier inside radix_tree_iter_replace() */ 510a835c4fSMatthew Wilcox radix_tree_iter_replace(&idr->idr_rt, &iter, slot, ptr); 520a835c4fSMatthew Wilcox radix_tree_iter_tag_clear(&idr->idr_rt, &iter, IDR_FREE); 53388f79fdSChris Mi 54388f79fdSChris Mi return 0; 55d5c7409fSTejun Heo } 56460488c5SMatthew Wilcox EXPORT_SYMBOL_GPL(idr_alloc_u32); 57d5c7409fSTejun Heo 583e6628c4SJeff Layton /** 59460488c5SMatthew Wilcox * idr_alloc() - Allocate an ID. 60460488c5SMatthew Wilcox * @idr: IDR handle. 61460488c5SMatthew Wilcox * @ptr: Pointer to be associated with the new ID. 62460488c5SMatthew Wilcox * @start: The minimum ID (inclusive). 63460488c5SMatthew Wilcox * @end: The maximum ID (exclusive). 64460488c5SMatthew Wilcox * @gfp: Memory allocation flags. 653e6628c4SJeff Layton * 66460488c5SMatthew Wilcox * Allocates an unused ID in the range specified by @start and @end. If 67460488c5SMatthew Wilcox * @end is <= 0, it is treated as one larger than %INT_MAX. This allows 68460488c5SMatthew Wilcox * callers to use @start + N as @end as long as N is within integer range. 69460488c5SMatthew Wilcox * 70460488c5SMatthew Wilcox * The caller should provide their own locking to ensure that two 71460488c5SMatthew Wilcox * concurrent modifications to the IDR are not possible. Read-only 72460488c5SMatthew Wilcox * accesses to the IDR may be done under the RCU read lock or may 73460488c5SMatthew Wilcox * exclude simultaneous writers. 74460488c5SMatthew Wilcox * 75460488c5SMatthew Wilcox * Return: The newly allocated ID, -ENOMEM if memory allocation failed, 76460488c5SMatthew Wilcox * or -ENOSPC if no free IDs could be found. 77460488c5SMatthew Wilcox */ 78460488c5SMatthew Wilcox int idr_alloc(struct idr *idr, void *ptr, int start, int end, gfp_t gfp) 79460488c5SMatthew Wilcox { 80460488c5SMatthew Wilcox u32 id = start; 81460488c5SMatthew Wilcox int ret; 82460488c5SMatthew Wilcox 83460488c5SMatthew Wilcox if (WARN_ON_ONCE(start < 0)) 84460488c5SMatthew Wilcox return -EINVAL; 85460488c5SMatthew Wilcox 86460488c5SMatthew Wilcox ret = idr_alloc_u32(idr, ptr, &id, end > 0 ? end - 1 : INT_MAX, gfp); 87460488c5SMatthew Wilcox if (ret) 88460488c5SMatthew Wilcox return ret; 89460488c5SMatthew Wilcox 90460488c5SMatthew Wilcox return id; 91460488c5SMatthew Wilcox } 92460488c5SMatthew Wilcox EXPORT_SYMBOL_GPL(idr_alloc); 93460488c5SMatthew Wilcox 94460488c5SMatthew Wilcox /** 95460488c5SMatthew Wilcox * idr_alloc_cyclic() - Allocate an ID cyclically. 96460488c5SMatthew Wilcox * @idr: IDR handle. 97460488c5SMatthew Wilcox * @ptr: Pointer to be associated with the new ID. 98460488c5SMatthew Wilcox * @start: The minimum ID (inclusive). 99460488c5SMatthew Wilcox * @end: The maximum ID (exclusive). 100460488c5SMatthew Wilcox * @gfp: Memory allocation flags. 101460488c5SMatthew Wilcox * 102460488c5SMatthew Wilcox * Allocates an unused ID in the range specified by @nextid and @end. If 103460488c5SMatthew Wilcox * @end is <= 0, it is treated as one larger than %INT_MAX. This allows 104460488c5SMatthew Wilcox * callers to use @start + N as @end as long as N is within integer range. 105460488c5SMatthew Wilcox * The search for an unused ID will start at the last ID allocated and will 106460488c5SMatthew Wilcox * wrap around to @start if no free IDs are found before reaching @end. 107460488c5SMatthew Wilcox * 108460488c5SMatthew Wilcox * The caller should provide their own locking to ensure that two 109460488c5SMatthew Wilcox * concurrent modifications to the IDR are not possible. Read-only 110460488c5SMatthew Wilcox * accesses to the IDR may be done under the RCU read lock or may 111460488c5SMatthew Wilcox * exclude simultaneous writers. 112460488c5SMatthew Wilcox * 113460488c5SMatthew Wilcox * Return: The newly allocated ID, -ENOMEM if memory allocation failed, 114460488c5SMatthew Wilcox * or -ENOSPC if no free IDs could be found. 1153e6628c4SJeff Layton */ 1160a835c4fSMatthew Wilcox int idr_alloc_cyclic(struct idr *idr, void *ptr, int start, int end, gfp_t gfp) 1173e6628c4SJeff Layton { 118460488c5SMatthew Wilcox u32 id = idr->idr_next; 119460488c5SMatthew Wilcox int err, max = end > 0 ? end - 1 : INT_MAX; 1203e6628c4SJeff Layton 121460488c5SMatthew Wilcox if ((int)id < start) 122460488c5SMatthew Wilcox id = start; 1233e6628c4SJeff Layton 124460488c5SMatthew Wilcox err = idr_alloc_u32(idr, ptr, &id, max, gfp); 125460488c5SMatthew Wilcox if ((err == -ENOSPC) && (id > start)) { 126460488c5SMatthew Wilcox id = start; 127460488c5SMatthew Wilcox err = idr_alloc_u32(idr, ptr, &id, max, gfp); 128460488c5SMatthew Wilcox } 129460488c5SMatthew Wilcox if (err) 130460488c5SMatthew Wilcox return err; 1310a835c4fSMatthew Wilcox 132460488c5SMatthew Wilcox idr->idr_next = id + 1; 1333e6628c4SJeff Layton return id; 1343e6628c4SJeff Layton } 1353e6628c4SJeff Layton EXPORT_SYMBOL(idr_alloc_cyclic); 1363e6628c4SJeff Layton 1375806f07cSJeff Mahoney /** 1386ce711f2SMatthew Wilcox * idr_remove() - Remove an ID from the IDR. 1396ce711f2SMatthew Wilcox * @idr: IDR handle. 1406ce711f2SMatthew Wilcox * @id: Pointer ID. 1416ce711f2SMatthew Wilcox * 1426ce711f2SMatthew Wilcox * Removes this ID from the IDR. If the ID was not previously in the IDR, 1436ce711f2SMatthew Wilcox * this function returns %NULL. 1446ce711f2SMatthew Wilcox * 1456ce711f2SMatthew Wilcox * Since this function modifies the IDR, the caller should provide their 1466ce711f2SMatthew Wilcox * own locking to ensure that concurrent modification of the same IDR is 1476ce711f2SMatthew Wilcox * not possible. 1486ce711f2SMatthew Wilcox * 1496ce711f2SMatthew Wilcox * Return: The pointer formerly associated with this ID. 1506ce711f2SMatthew Wilcox */ 1516ce711f2SMatthew Wilcox void *idr_remove(struct idr *idr, unsigned long id) 1526ce711f2SMatthew Wilcox { 1536ce711f2SMatthew Wilcox return radix_tree_delete_item(&idr->idr_rt, id - idr->idr_base, NULL); 1546ce711f2SMatthew Wilcox } 1556ce711f2SMatthew Wilcox EXPORT_SYMBOL_GPL(idr_remove); 1566ce711f2SMatthew Wilcox 1576ce711f2SMatthew Wilcox /** 1586ce711f2SMatthew Wilcox * idr_find() - Return pointer for given ID. 1596ce711f2SMatthew Wilcox * @idr: IDR handle. 1606ce711f2SMatthew Wilcox * @id: Pointer ID. 1616ce711f2SMatthew Wilcox * 1626ce711f2SMatthew Wilcox * Looks up the pointer associated with this ID. A %NULL pointer may 1636ce711f2SMatthew Wilcox * indicate that @id is not allocated or that the %NULL pointer was 1646ce711f2SMatthew Wilcox * associated with this ID. 1656ce711f2SMatthew Wilcox * 1666ce711f2SMatthew Wilcox * This function can be called under rcu_read_lock(), given that the leaf 1676ce711f2SMatthew Wilcox * pointers lifetimes are correctly managed. 1686ce711f2SMatthew Wilcox * 1696ce711f2SMatthew Wilcox * Return: The pointer associated with this ID. 1706ce711f2SMatthew Wilcox */ 1716ce711f2SMatthew Wilcox void *idr_find(const struct idr *idr, unsigned long id) 1726ce711f2SMatthew Wilcox { 1736ce711f2SMatthew Wilcox return radix_tree_lookup(&idr->idr_rt, id - idr->idr_base); 1746ce711f2SMatthew Wilcox } 1756ce711f2SMatthew Wilcox EXPORT_SYMBOL_GPL(idr_find); 1766ce711f2SMatthew Wilcox 1776ce711f2SMatthew Wilcox /** 1787a457577SMatthew Wilcox * idr_for_each() - Iterate through all stored pointers. 1797a457577SMatthew Wilcox * @idr: IDR handle. 1807a457577SMatthew Wilcox * @fn: Function to be called for each pointer. 1817a457577SMatthew Wilcox * @data: Data passed to callback function. 18296d7fa42SKristian Hoegsberg * 1830a835c4fSMatthew Wilcox * The callback function will be called for each entry in @idr, passing 1847a457577SMatthew Wilcox * the ID, the entry and @data. 18596d7fa42SKristian Hoegsberg * 1860a835c4fSMatthew Wilcox * If @fn returns anything other than %0, the iteration stops and that 1870a835c4fSMatthew Wilcox * value is returned from this function. 18896d7fa42SKristian Hoegsberg * 1890a835c4fSMatthew Wilcox * idr_for_each() can be called concurrently with idr_alloc() and 1900a835c4fSMatthew Wilcox * idr_remove() if protected by RCU. Newly added entries may not be 1910a835c4fSMatthew Wilcox * seen and deleted entries may be seen, but adding and removing entries 1920a835c4fSMatthew Wilcox * will not cause other entries to be skipped, nor spurious ones to be seen. 19396d7fa42SKristian Hoegsberg */ 1940a835c4fSMatthew Wilcox int idr_for_each(const struct idr *idr, 19596d7fa42SKristian Hoegsberg int (*fn)(int id, void *p, void *data), void *data) 19696d7fa42SKristian Hoegsberg { 1970a835c4fSMatthew Wilcox struct radix_tree_iter iter; 1987e73eb0bSMatthew Wilcox void __rcu **slot; 1996ce711f2SMatthew Wilcox int base = idr->idr_base; 20096d7fa42SKristian Hoegsberg 2010a835c4fSMatthew Wilcox radix_tree_for_each_slot(slot, &idr->idr_rt, &iter, 0) { 20272fd6c7bSMatthew Wilcox int ret; 2034b0ad076SMatthew Wilcox unsigned long id = iter.index + base; 20472fd6c7bSMatthew Wilcox 2054b0ad076SMatthew Wilcox if (WARN_ON_ONCE(id > INT_MAX)) 20672fd6c7bSMatthew Wilcox break; 2074b0ad076SMatthew Wilcox ret = fn(id, rcu_dereference_raw(*slot), data); 2080a835c4fSMatthew Wilcox if (ret) 2090a835c4fSMatthew Wilcox return ret; 21096d7fa42SKristian Hoegsberg } 21196d7fa42SKristian Hoegsberg 2120a835c4fSMatthew Wilcox return 0; 21396d7fa42SKristian Hoegsberg } 21496d7fa42SKristian Hoegsberg EXPORT_SYMBOL(idr_for_each); 21596d7fa42SKristian Hoegsberg 21696d7fa42SKristian Hoegsberg /** 2177a457577SMatthew Wilcox * idr_get_next() - Find next populated entry. 2187a457577SMatthew Wilcox * @idr: IDR handle. 2197a457577SMatthew Wilcox * @nextid: Pointer to an ID. 22038460b48SKAMEZAWA Hiroyuki * 2210a835c4fSMatthew Wilcox * Returns the next populated entry in the tree with an ID greater than 2220a835c4fSMatthew Wilcox * or equal to the value pointed to by @nextid. On exit, @nextid is updated 2230a835c4fSMatthew Wilcox * to the ID of the found value. To use in a loop, the value pointed to by 2240a835c4fSMatthew Wilcox * nextid must be incremented by the user. 22538460b48SKAMEZAWA Hiroyuki */ 2260a835c4fSMatthew Wilcox void *idr_get_next(struct idr *idr, int *nextid) 22738460b48SKAMEZAWA Hiroyuki { 2280a835c4fSMatthew Wilcox struct radix_tree_iter iter; 2297e73eb0bSMatthew Wilcox void __rcu **slot; 2304b0ad076SMatthew Wilcox unsigned long base = idr->idr_base; 2314b0ad076SMatthew Wilcox unsigned long id = *nextid; 23238460b48SKAMEZAWA Hiroyuki 2336ce711f2SMatthew Wilcox id = (id < base) ? 0 : id - base; 2346ce711f2SMatthew Wilcox slot = radix_tree_iter_find(&idr->idr_rt, &iter, id); 2350a835c4fSMatthew Wilcox if (!slot) 23638460b48SKAMEZAWA Hiroyuki return NULL; 2376ce711f2SMatthew Wilcox id = iter.index + base; 23838460b48SKAMEZAWA Hiroyuki 2396ce711f2SMatthew Wilcox if (WARN_ON_ONCE(id > INT_MAX)) 24072fd6c7bSMatthew Wilcox return NULL; 24172fd6c7bSMatthew Wilcox 2426ce711f2SMatthew Wilcox *nextid = id; 2430a835c4fSMatthew Wilcox return rcu_dereference_raw(*slot); 24438460b48SKAMEZAWA Hiroyuki } 2454d1ee80fSBen Hutchings EXPORT_SYMBOL(idr_get_next); 24638460b48SKAMEZAWA Hiroyuki 2477a457577SMatthew Wilcox /** 2487a457577SMatthew Wilcox * idr_get_next_ul() - Find next populated entry. 2497a457577SMatthew Wilcox * @idr: IDR handle. 2507a457577SMatthew Wilcox * @nextid: Pointer to an ID. 2517a457577SMatthew Wilcox * 2527a457577SMatthew Wilcox * Returns the next populated entry in the tree with an ID greater than 2537a457577SMatthew Wilcox * or equal to the value pointed to by @nextid. On exit, @nextid is updated 2547a457577SMatthew Wilcox * to the ID of the found value. To use in a loop, the value pointed to by 2557a457577SMatthew Wilcox * nextid must be incremented by the user. 2567a457577SMatthew Wilcox */ 2577a457577SMatthew Wilcox void *idr_get_next_ul(struct idr *idr, unsigned long *nextid) 258388f79fdSChris Mi { 259388f79fdSChris Mi struct radix_tree_iter iter; 260388f79fdSChris Mi void __rcu **slot; 2616ce711f2SMatthew Wilcox unsigned long base = idr->idr_base; 2626ce711f2SMatthew Wilcox unsigned long id = *nextid; 263388f79fdSChris Mi 2646ce711f2SMatthew Wilcox id = (id < base) ? 0 : id - base; 2656ce711f2SMatthew Wilcox slot = radix_tree_iter_find(&idr->idr_rt, &iter, id); 266388f79fdSChris Mi if (!slot) 267388f79fdSChris Mi return NULL; 268388f79fdSChris Mi 2696ce711f2SMatthew Wilcox *nextid = iter.index + base; 270388f79fdSChris Mi return rcu_dereference_raw(*slot); 271388f79fdSChris Mi } 2727a457577SMatthew Wilcox EXPORT_SYMBOL(idr_get_next_ul); 273388f79fdSChris Mi 27438460b48SKAMEZAWA Hiroyuki /** 275460488c5SMatthew Wilcox * idr_replace() - replace pointer for given ID. 276460488c5SMatthew Wilcox * @idr: IDR handle. 277460488c5SMatthew Wilcox * @ptr: New pointer to associate with the ID. 278460488c5SMatthew Wilcox * @id: ID to change. 2795806f07cSJeff Mahoney * 2800a835c4fSMatthew Wilcox * Replace the pointer registered with an ID and return the old value. 2810a835c4fSMatthew Wilcox * This function can be called under the RCU read lock concurrently with 2820a835c4fSMatthew Wilcox * idr_alloc() and idr_remove() (as long as the ID being removed is not 2830a835c4fSMatthew Wilcox * the one being replaced!). 2845806f07cSJeff Mahoney * 285a70e43a5SEric Biggers * Returns: the old value on success. %-ENOENT indicates that @id was not 286234a4624SMatthew Wilcox * found. %-EINVAL indicates that @ptr was not valid. 2875806f07cSJeff Mahoney */ 288234a4624SMatthew Wilcox void *idr_replace(struct idr *idr, void *ptr, unsigned long id) 289388f79fdSChris Mi { 2900a835c4fSMatthew Wilcox struct radix_tree_node *node; 2917e73eb0bSMatthew Wilcox void __rcu **slot = NULL; 2920a835c4fSMatthew Wilcox void *entry; 2935806f07cSJeff Mahoney 2946ce711f2SMatthew Wilcox id -= idr->idr_base; 295e8c8d1bcSTejun Heo 2960a835c4fSMatthew Wilcox entry = __radix_tree_lookup(&idr->idr_rt, id, &node, &slot); 2970a835c4fSMatthew Wilcox if (!slot || radix_tree_tag_get(&idr->idr_rt, id, IDR_FREE)) 298b93804b2SLai Jiangshan return ERR_PTR(-ENOENT); 2996ff2d39bSManfred Spraul 3001cf56f9dSMatthew Wilcox __radix_tree_replace(&idr->idr_rt, node, slot, ptr); 3015806f07cSJeff Mahoney 3020a835c4fSMatthew Wilcox return entry; 3035806f07cSJeff Mahoney } 304234a4624SMatthew Wilcox EXPORT_SYMBOL(idr_replace); 3055806f07cSJeff Mahoney 30656083ab1SRandy Dunlap /** 30756083ab1SRandy Dunlap * DOC: IDA description 30872dba584STejun Heo * 3090a835c4fSMatthew Wilcox * The IDA is an ID allocator which does not provide the ability to 3100a835c4fSMatthew Wilcox * associate an ID with a pointer. As such, it only needs to store one 3110a835c4fSMatthew Wilcox * bit per ID, and so is more space efficient than an IDR. To use an IDA, 3120a835c4fSMatthew Wilcox * define it using DEFINE_IDA() (or embed a &struct ida in a data structure, 3130a835c4fSMatthew Wilcox * then initialise it using ida_init()). To allocate a new ID, call 3145ade60ddSMatthew Wilcox * ida_alloc(), ida_alloc_min(), ida_alloc_max() or ida_alloc_range(). 3155ade60ddSMatthew Wilcox * To free an ID, call ida_free(). 31672dba584STejun Heo * 317b03f8e43SMatthew Wilcox * ida_destroy() can be used to dispose of an IDA without needing to 318b03f8e43SMatthew Wilcox * free the individual IDs in it. You can use ida_is_empty() to find 319b03f8e43SMatthew Wilcox * out whether the IDA has any IDs currently allocated. 3200a835c4fSMatthew Wilcox * 321f32f004cSMatthew Wilcox * The IDA handles its own locking. It is safe to call any of the IDA 322f32f004cSMatthew Wilcox * functions without synchronisation in your code. 323f32f004cSMatthew Wilcox * 3240a835c4fSMatthew Wilcox * IDs are currently limited to the range [0-INT_MAX]. If this is an awkward 3250a835c4fSMatthew Wilcox * limitation, it should be quite straightforward to raise the maximum. 32672dba584STejun Heo */ 32772dba584STejun Heo 328d37cacc5SMatthew Wilcox /* 329d37cacc5SMatthew Wilcox * Developer's notes: 330d37cacc5SMatthew Wilcox * 331f32f004cSMatthew Wilcox * The IDA uses the functionality provided by the XArray to store bitmaps in 332f32f004cSMatthew Wilcox * each entry. The XA_FREE_MARK is only cleared when all bits in the bitmap 333f32f004cSMatthew Wilcox * have been set. 334d37cacc5SMatthew Wilcox * 335f32f004cSMatthew Wilcox * I considered telling the XArray that each slot is an order-10 node 336f32f004cSMatthew Wilcox * and indexing by bit number, but the XArray can't allow a single multi-index 337f32f004cSMatthew Wilcox * entry in the head, which would significantly increase memory consumption 338f32f004cSMatthew Wilcox * for the IDA. So instead we divide the index by the number of bits in the 339f32f004cSMatthew Wilcox * leaf bitmap before doing a radix tree lookup. 340d37cacc5SMatthew Wilcox * 341d37cacc5SMatthew Wilcox * As an optimisation, if there are only a few low bits set in any given 3423159f943SMatthew Wilcox * leaf, instead of allocating a 128-byte bitmap, we store the bits 343f32f004cSMatthew Wilcox * as a value entry. Value entries never have the XA_FREE_MARK cleared 344f32f004cSMatthew Wilcox * because we can always convert them into a bitmap entry. 345d37cacc5SMatthew Wilcox * 346f32f004cSMatthew Wilcox * It would be possible to optimise further; once we've run out of a 347f32f004cSMatthew Wilcox * single 128-byte bitmap, we currently switch to a 576-byte node, put 348f32f004cSMatthew Wilcox * the 128-byte bitmap in the first entry and then start allocating extra 349f32f004cSMatthew Wilcox * 128-byte entries. We could instead use the 512 bytes of the node's 350f32f004cSMatthew Wilcox * data as a bitmap before moving to that scheme. I do not believe this 351f32f004cSMatthew Wilcox * is a worthwhile optimisation; Rasmus Villemoes surveyed the current 352f32f004cSMatthew Wilcox * users of the IDA and almost none of them use more than 1024 entries. 353f32f004cSMatthew Wilcox * Those that do use more than the 8192 IDs that the 512 bytes would 354f32f004cSMatthew Wilcox * provide. 355d37cacc5SMatthew Wilcox * 356f32f004cSMatthew Wilcox * The IDA always uses a lock to alloc/free. If we add a 'test_bit' 357d37cacc5SMatthew Wilcox * equivalent, it will still need locking. Going to RCU lookup would require 358d37cacc5SMatthew Wilcox * using RCU to free bitmaps, and that's not trivial without embedding an 359d37cacc5SMatthew Wilcox * RCU head in the bitmap, which adds a 2-pointer overhead to each 128-byte 360d37cacc5SMatthew Wilcox * bitmap, which is excessive. 361d37cacc5SMatthew Wilcox */ 362d37cacc5SMatthew Wilcox 36372dba584STejun Heo /** 3645ade60ddSMatthew Wilcox * ida_alloc_range() - Allocate an unused ID. 3655ade60ddSMatthew Wilcox * @ida: IDA handle. 3665ade60ddSMatthew Wilcox * @min: Lowest ID to allocate. 3675ade60ddSMatthew Wilcox * @max: Highest ID to allocate. 3685ade60ddSMatthew Wilcox * @gfp: Memory allocation flags. 36988eca020SRusty Russell * 3705ade60ddSMatthew Wilcox * Allocate an ID between @min and @max, inclusive. The allocated ID will 3715ade60ddSMatthew Wilcox * not exceed %INT_MAX, even if @max is larger. 37288eca020SRusty Russell * 3735ade60ddSMatthew Wilcox * Context: Any context. 3745ade60ddSMatthew Wilcox * Return: The allocated ID, or %-ENOMEM if memory could not be allocated, 3755ade60ddSMatthew Wilcox * or %-ENOSPC if there are no free IDs. 37688eca020SRusty Russell */ 3775ade60ddSMatthew Wilcox int ida_alloc_range(struct ida *ida, unsigned int min, unsigned int max, 3785ade60ddSMatthew Wilcox gfp_t gfp) 37988eca020SRusty Russell { 380f32f004cSMatthew Wilcox XA_STATE(xas, &ida->xa, min / IDA_BITMAP_BITS); 381f32f004cSMatthew Wilcox unsigned bit = min % IDA_BITMAP_BITS; 38246cbc1d3STejun Heo unsigned long flags; 383f32f004cSMatthew Wilcox struct ida_bitmap *bitmap, *alloc = NULL; 38488eca020SRusty Russell 3855ade60ddSMatthew Wilcox if ((int)min < 0) 3865ade60ddSMatthew Wilcox return -ENOSPC; 38788eca020SRusty Russell 3885ade60ddSMatthew Wilcox if ((int)max < 0) 3895ade60ddSMatthew Wilcox max = INT_MAX; 39088eca020SRusty Russell 391f32f004cSMatthew Wilcox retry: 392f32f004cSMatthew Wilcox xas_lock_irqsave(&xas, flags); 393f32f004cSMatthew Wilcox next: 394f32f004cSMatthew Wilcox bitmap = xas_find_marked(&xas, max / IDA_BITMAP_BITS, XA_FREE_MARK); 395f32f004cSMatthew Wilcox if (xas.xa_index > min / IDA_BITMAP_BITS) 396f32f004cSMatthew Wilcox bit = 0; 397f32f004cSMatthew Wilcox if (xas.xa_index * IDA_BITMAP_BITS + bit > max) 398f32f004cSMatthew Wilcox goto nospc; 39988eca020SRusty Russell 400f32f004cSMatthew Wilcox if (xa_is_value(bitmap)) { 401f32f004cSMatthew Wilcox unsigned long tmp = xa_to_value(bitmap); 402f32f004cSMatthew Wilcox 403f32f004cSMatthew Wilcox if (bit < BITS_PER_XA_VALUE) { 404f32f004cSMatthew Wilcox bit = find_next_zero_bit(&tmp, BITS_PER_XA_VALUE, bit); 405f32f004cSMatthew Wilcox if (xas.xa_index * IDA_BITMAP_BITS + bit > max) 406f32f004cSMatthew Wilcox goto nospc; 407f32f004cSMatthew Wilcox if (bit < BITS_PER_XA_VALUE) { 408f32f004cSMatthew Wilcox tmp |= 1UL << bit; 409f32f004cSMatthew Wilcox xas_store(&xas, xa_mk_value(tmp)); 410f32f004cSMatthew Wilcox goto out; 411f32f004cSMatthew Wilcox } 412f32f004cSMatthew Wilcox } 413f32f004cSMatthew Wilcox bitmap = alloc; 414f32f004cSMatthew Wilcox if (!bitmap) 415f32f004cSMatthew Wilcox bitmap = kzalloc(sizeof(*bitmap), GFP_NOWAIT); 416f32f004cSMatthew Wilcox if (!bitmap) 417f32f004cSMatthew Wilcox goto alloc; 418f32f004cSMatthew Wilcox bitmap->bitmap[0] = tmp; 419f32f004cSMatthew Wilcox xas_store(&xas, bitmap); 420f32f004cSMatthew Wilcox if (xas_error(&xas)) { 421f32f004cSMatthew Wilcox bitmap->bitmap[0] = 0; 422f32f004cSMatthew Wilcox goto out; 423f32f004cSMatthew Wilcox } 424f32f004cSMatthew Wilcox } 425f32f004cSMatthew Wilcox 426f32f004cSMatthew Wilcox if (bitmap) { 427f32f004cSMatthew Wilcox bit = find_next_zero_bit(bitmap->bitmap, IDA_BITMAP_BITS, bit); 428f32f004cSMatthew Wilcox if (xas.xa_index * IDA_BITMAP_BITS + bit > max) 429f32f004cSMatthew Wilcox goto nospc; 430f32f004cSMatthew Wilcox if (bit == IDA_BITMAP_BITS) 431f32f004cSMatthew Wilcox goto next; 432f32f004cSMatthew Wilcox 433f32f004cSMatthew Wilcox __set_bit(bit, bitmap->bitmap); 434f32f004cSMatthew Wilcox if (bitmap_full(bitmap->bitmap, IDA_BITMAP_BITS)) 435f32f004cSMatthew Wilcox xas_clear_mark(&xas, XA_FREE_MARK); 436f32f004cSMatthew Wilcox } else { 437f32f004cSMatthew Wilcox if (bit < BITS_PER_XA_VALUE) { 438f32f004cSMatthew Wilcox bitmap = xa_mk_value(1UL << bit); 439f32f004cSMatthew Wilcox } else { 440f32f004cSMatthew Wilcox bitmap = alloc; 441f32f004cSMatthew Wilcox if (!bitmap) 442f32f004cSMatthew Wilcox bitmap = kzalloc(sizeof(*bitmap), GFP_NOWAIT); 443f32f004cSMatthew Wilcox if (!bitmap) 444f32f004cSMatthew Wilcox goto alloc; 445f32f004cSMatthew Wilcox __set_bit(bit, bitmap->bitmap); 446f32f004cSMatthew Wilcox } 447f32f004cSMatthew Wilcox xas_store(&xas, bitmap); 448f32f004cSMatthew Wilcox } 449f32f004cSMatthew Wilcox out: 450f32f004cSMatthew Wilcox xas_unlock_irqrestore(&xas, flags); 451f32f004cSMatthew Wilcox if (xas_nomem(&xas, gfp)) { 452f32f004cSMatthew Wilcox xas.xa_index = min / IDA_BITMAP_BITS; 453f32f004cSMatthew Wilcox bit = min % IDA_BITMAP_BITS; 454f32f004cSMatthew Wilcox goto retry; 455f32f004cSMatthew Wilcox } 456f32f004cSMatthew Wilcox if (bitmap != alloc) 457f32f004cSMatthew Wilcox kfree(alloc); 458f32f004cSMatthew Wilcox if (xas_error(&xas)) 459f32f004cSMatthew Wilcox return xas_error(&xas); 460f32f004cSMatthew Wilcox return xas.xa_index * IDA_BITMAP_BITS + bit; 461f32f004cSMatthew Wilcox alloc: 462f32f004cSMatthew Wilcox xas_unlock_irqrestore(&xas, flags); 463f32f004cSMatthew Wilcox alloc = kzalloc(sizeof(*bitmap), gfp); 464f32f004cSMatthew Wilcox if (!alloc) 4655ade60ddSMatthew Wilcox return -ENOMEM; 466f32f004cSMatthew Wilcox xas_set(&xas, min / IDA_BITMAP_BITS); 467f32f004cSMatthew Wilcox bit = min % IDA_BITMAP_BITS; 468f32f004cSMatthew Wilcox goto retry; 469f32f004cSMatthew Wilcox nospc: 470f32f004cSMatthew Wilcox xas_unlock_irqrestore(&xas, flags); 471f32f004cSMatthew Wilcox return -ENOSPC; 47288eca020SRusty Russell } 4735ade60ddSMatthew Wilcox EXPORT_SYMBOL(ida_alloc_range); 47488eca020SRusty Russell 47588eca020SRusty Russell /** 4765ade60ddSMatthew Wilcox * ida_free() - Release an allocated ID. 4775ade60ddSMatthew Wilcox * @ida: IDA handle. 4785ade60ddSMatthew Wilcox * @id: Previously allocated ID. 479a2ef9471SDaniel Vetter * 4805ade60ddSMatthew Wilcox * Context: Any context. 48188eca020SRusty Russell */ 4825ade60ddSMatthew Wilcox void ida_free(struct ida *ida, unsigned int id) 48388eca020SRusty Russell { 484f32f004cSMatthew Wilcox XA_STATE(xas, &ida->xa, id / IDA_BITMAP_BITS); 485f32f004cSMatthew Wilcox unsigned bit = id % IDA_BITMAP_BITS; 486f32f004cSMatthew Wilcox struct ida_bitmap *bitmap; 48746cbc1d3STejun Heo unsigned long flags; 48846cbc1d3STejun Heo 48988eca020SRusty Russell BUG_ON((int)id < 0); 490f32f004cSMatthew Wilcox 491f32f004cSMatthew Wilcox xas_lock_irqsave(&xas, flags); 492f32f004cSMatthew Wilcox bitmap = xas_load(&xas); 493f32f004cSMatthew Wilcox 494f32f004cSMatthew Wilcox if (xa_is_value(bitmap)) { 495f32f004cSMatthew Wilcox unsigned long v = xa_to_value(bitmap); 496f32f004cSMatthew Wilcox if (bit >= BITS_PER_XA_VALUE) 497f32f004cSMatthew Wilcox goto err; 498f32f004cSMatthew Wilcox if (!(v & (1UL << bit))) 499f32f004cSMatthew Wilcox goto err; 500f32f004cSMatthew Wilcox v &= ~(1UL << bit); 501f32f004cSMatthew Wilcox if (!v) 502f32f004cSMatthew Wilcox goto delete; 503f32f004cSMatthew Wilcox xas_store(&xas, xa_mk_value(v)); 504f32f004cSMatthew Wilcox } else { 505f32f004cSMatthew Wilcox if (!test_bit(bit, bitmap->bitmap)) 506f32f004cSMatthew Wilcox goto err; 507f32f004cSMatthew Wilcox __clear_bit(bit, bitmap->bitmap); 508f32f004cSMatthew Wilcox xas_set_mark(&xas, XA_FREE_MARK); 509f32f004cSMatthew Wilcox if (bitmap_empty(bitmap->bitmap, IDA_BITMAP_BITS)) { 510f32f004cSMatthew Wilcox kfree(bitmap); 511f32f004cSMatthew Wilcox delete: 512f32f004cSMatthew Wilcox xas_store(&xas, NULL); 513f32f004cSMatthew Wilcox } 514f32f004cSMatthew Wilcox } 515f32f004cSMatthew Wilcox xas_unlock_irqrestore(&xas, flags); 516f32f004cSMatthew Wilcox return; 517f32f004cSMatthew Wilcox err: 518f32f004cSMatthew Wilcox xas_unlock_irqrestore(&xas, flags); 519f32f004cSMatthew Wilcox WARN(1, "ida_free called for id=%d which is not allocated.\n", id); 52088eca020SRusty Russell } 5215ade60ddSMatthew Wilcox EXPORT_SYMBOL(ida_free); 522f32f004cSMatthew Wilcox 523f32f004cSMatthew Wilcox /** 524f32f004cSMatthew Wilcox * ida_destroy() - Free all IDs. 525f32f004cSMatthew Wilcox * @ida: IDA handle. 526f32f004cSMatthew Wilcox * 527f32f004cSMatthew Wilcox * Calling this function frees all IDs and releases all resources used 528f32f004cSMatthew Wilcox * by an IDA. When this call returns, the IDA is empty and can be reused 529f32f004cSMatthew Wilcox * or freed. If the IDA is already empty, there is no need to call this 530f32f004cSMatthew Wilcox * function. 531f32f004cSMatthew Wilcox * 532f32f004cSMatthew Wilcox * Context: Any context. 533f32f004cSMatthew Wilcox */ 534f32f004cSMatthew Wilcox void ida_destroy(struct ida *ida) 535f32f004cSMatthew Wilcox { 536f32f004cSMatthew Wilcox XA_STATE(xas, &ida->xa, 0); 537f32f004cSMatthew Wilcox struct ida_bitmap *bitmap; 538f32f004cSMatthew Wilcox unsigned long flags; 539f32f004cSMatthew Wilcox 540f32f004cSMatthew Wilcox xas_lock_irqsave(&xas, flags); 541f32f004cSMatthew Wilcox xas_for_each(&xas, bitmap, ULONG_MAX) { 542f32f004cSMatthew Wilcox if (!xa_is_value(bitmap)) 543f32f004cSMatthew Wilcox kfree(bitmap); 544f32f004cSMatthew Wilcox xas_store(&xas, NULL); 545f32f004cSMatthew Wilcox } 546f32f004cSMatthew Wilcox xas_unlock_irqrestore(&xas, flags); 547f32f004cSMatthew Wilcox } 548f32f004cSMatthew Wilcox EXPORT_SYMBOL(ida_destroy); 549f32f004cSMatthew Wilcox 550f32f004cSMatthew Wilcox #ifndef __KERNEL__ 551f32f004cSMatthew Wilcox extern void xa_dump_index(unsigned long index, unsigned int shift); 552f32f004cSMatthew Wilcox #define IDA_CHUNK_SHIFT ilog2(IDA_BITMAP_BITS) 553f32f004cSMatthew Wilcox 554f32f004cSMatthew Wilcox static void ida_dump_entry(void *entry, unsigned long index) 555f32f004cSMatthew Wilcox { 556f32f004cSMatthew Wilcox unsigned long i; 557f32f004cSMatthew Wilcox 558f32f004cSMatthew Wilcox if (!entry) 559f32f004cSMatthew Wilcox return; 560f32f004cSMatthew Wilcox 561f32f004cSMatthew Wilcox if (xa_is_node(entry)) { 562f32f004cSMatthew Wilcox struct xa_node *node = xa_to_node(entry); 563f32f004cSMatthew Wilcox unsigned int shift = node->shift + IDA_CHUNK_SHIFT + 564f32f004cSMatthew Wilcox XA_CHUNK_SHIFT; 565f32f004cSMatthew Wilcox 566f32f004cSMatthew Wilcox xa_dump_index(index * IDA_BITMAP_BITS, shift); 567f32f004cSMatthew Wilcox xa_dump_node(node); 568f32f004cSMatthew Wilcox for (i = 0; i < XA_CHUNK_SIZE; i++) 569f32f004cSMatthew Wilcox ida_dump_entry(node->slots[i], 570f32f004cSMatthew Wilcox index | (i << node->shift)); 571f32f004cSMatthew Wilcox } else if (xa_is_value(entry)) { 572f32f004cSMatthew Wilcox xa_dump_index(index * IDA_BITMAP_BITS, ilog2(BITS_PER_LONG)); 573f32f004cSMatthew Wilcox pr_cont("value: data %lx [%px]\n", xa_to_value(entry), entry); 574f32f004cSMatthew Wilcox } else { 575f32f004cSMatthew Wilcox struct ida_bitmap *bitmap = entry; 576f32f004cSMatthew Wilcox 577f32f004cSMatthew Wilcox xa_dump_index(index * IDA_BITMAP_BITS, IDA_CHUNK_SHIFT); 578f32f004cSMatthew Wilcox pr_cont("bitmap: %p data", bitmap); 579f32f004cSMatthew Wilcox for (i = 0; i < IDA_BITMAP_LONGS; i++) 580f32f004cSMatthew Wilcox pr_cont(" %lx", bitmap->bitmap[i]); 581f32f004cSMatthew Wilcox pr_cont("\n"); 582f32f004cSMatthew Wilcox } 583f32f004cSMatthew Wilcox } 584f32f004cSMatthew Wilcox 585f32f004cSMatthew Wilcox static void ida_dump(struct ida *ida) 586f32f004cSMatthew Wilcox { 587f32f004cSMatthew Wilcox struct xarray *xa = &ida->xa; 588f32f004cSMatthew Wilcox pr_debug("ida: %p node %p free %d\n", ida, xa->xa_head, 589f32f004cSMatthew Wilcox xa->xa_flags >> ROOT_TAG_SHIFT); 590f32f004cSMatthew Wilcox ida_dump_entry(xa->xa_head, 0); 591f32f004cSMatthew Wilcox } 592f32f004cSMatthew Wilcox #endif 593