11da177e4SLinus Torvalds /* 21da177e4SLinus Torvalds * 2002-10-18 written by Jim Houston jim.houston@ccur.com 31da177e4SLinus Torvalds * Copyright (C) 2002 by Concurrent Computer Corporation 41da177e4SLinus Torvalds * Distributed under the GNU GPL license version 2. 51da177e4SLinus Torvalds * 61da177e4SLinus Torvalds * Modified by George Anzinger to reuse immediately and to use 71da177e4SLinus Torvalds * find bit instructions. Also removed _irq on spinlocks. 81da177e4SLinus Torvalds * 93219b3b7SNadia Derbey * Modified by Nadia Derbey to make it RCU safe. 103219b3b7SNadia Derbey * 111da177e4SLinus Torvalds * Small id to pointer translation service. 121da177e4SLinus Torvalds * 131da177e4SLinus Torvalds * It uses a radix tree like structure as a sparse array indexed 141da177e4SLinus Torvalds * by the id to obtain the pointer. The bitmap makes allocating 151da177e4SLinus Torvalds * a new id quick. 161da177e4SLinus Torvalds * 171da177e4SLinus Torvalds * You call it to allocate an id (an int) an associate with that id a 181da177e4SLinus Torvalds * pointer or what ever, we treat it as a (void *). You can pass this 191da177e4SLinus Torvalds * id to a user for him to pass back at a later time. You then pass 201da177e4SLinus Torvalds * that id to this code and it returns your pointer. 211da177e4SLinus Torvalds 221da177e4SLinus Torvalds * You can release ids at any time. When all ids are released, most of 23125c4c70SFengguang Wu * the memory is returned (we keep MAX_IDR_FREE) in a local pool so we 241da177e4SLinus Torvalds * don't need to go to the memory "store" during an id allocate, just 251da177e4SLinus Torvalds * so you don't need to be too concerned about locking and conflicts 261da177e4SLinus Torvalds * with the slab allocator. 271da177e4SLinus Torvalds */ 281da177e4SLinus Torvalds 291da177e4SLinus Torvalds #ifndef TEST // to test in user space... 301da177e4SLinus Torvalds #include <linux/slab.h> 311da177e4SLinus Torvalds #include <linux/init.h> 328bc3bcc9SPaul Gortmaker #include <linux/export.h> 331da177e4SLinus Torvalds #endif 345806f07cSJeff Mahoney #include <linux/err.h> 351da177e4SLinus Torvalds #include <linux/string.h> 361da177e4SLinus Torvalds #include <linux/idr.h> 3788eca020SRusty Russell #include <linux/spinlock.h> 38d5c7409fSTejun Heo #include <linux/percpu.h> 39d5c7409fSTejun Heo #include <linux/hardirq.h> 401da177e4SLinus Torvalds 41e8c8d1bcSTejun Heo #define MAX_IDR_SHIFT (sizeof(int) * 8 - 1) 42e8c8d1bcSTejun Heo #define MAX_IDR_BIT (1U << MAX_IDR_SHIFT) 43e8c8d1bcSTejun Heo 44e8c8d1bcSTejun Heo /* Leave the possibility of an incomplete final layer */ 45e8c8d1bcSTejun Heo #define MAX_IDR_LEVEL ((MAX_IDR_SHIFT + IDR_BITS - 1) / IDR_BITS) 46e8c8d1bcSTejun Heo 47e8c8d1bcSTejun Heo /* Number of id_layer structs to leave in free list */ 48e8c8d1bcSTejun Heo #define MAX_IDR_FREE (MAX_IDR_LEVEL * 2) 49e8c8d1bcSTejun Heo 50e18b890bSChristoph Lameter static struct kmem_cache *idr_layer_cache; 51d5c7409fSTejun Heo static DEFINE_PER_CPU(struct idr_layer *, idr_preload_head); 52d5c7409fSTejun Heo static DEFINE_PER_CPU(int, idr_preload_cnt); 5388eca020SRusty Russell static DEFINE_SPINLOCK(simple_ida_lock); 541da177e4SLinus Torvalds 55326cf0f0STejun Heo /* the maximum ID which can be allocated given idr->layers */ 56326cf0f0STejun Heo static int idr_max(int layers) 57326cf0f0STejun Heo { 58326cf0f0STejun Heo int bits = min_t(int, layers * IDR_BITS, MAX_IDR_SHIFT); 59326cf0f0STejun Heo 60326cf0f0STejun Heo return (1 << bits) - 1; 61326cf0f0STejun Heo } 62326cf0f0STejun Heo 6354616283STejun Heo /* 6454616283STejun Heo * Prefix mask for an idr_layer at @layer. For layer 0, the prefix mask is 6554616283STejun Heo * all bits except for the lower IDR_BITS. For layer 1, 2 * IDR_BITS, and 6654616283STejun Heo * so on. 6754616283STejun Heo */ 6854616283STejun Heo static int idr_layer_prefix_mask(int layer) 6954616283STejun Heo { 7054616283STejun Heo return ~idr_max(layer + 1); 7154616283STejun Heo } 7254616283STejun Heo 734ae53789SNadia Derbey static struct idr_layer *get_from_free_list(struct idr *idp) 741da177e4SLinus Torvalds { 751da177e4SLinus Torvalds struct idr_layer *p; 76c259cc28SRoland Dreier unsigned long flags; 771da177e4SLinus Torvalds 78c259cc28SRoland Dreier spin_lock_irqsave(&idp->lock, flags); 791da177e4SLinus Torvalds if ((p = idp->id_free)) { 801da177e4SLinus Torvalds idp->id_free = p->ary[0]; 811da177e4SLinus Torvalds idp->id_free_cnt--; 821da177e4SLinus Torvalds p->ary[0] = NULL; 831da177e4SLinus Torvalds } 84c259cc28SRoland Dreier spin_unlock_irqrestore(&idp->lock, flags); 851da177e4SLinus Torvalds return(p); 861da177e4SLinus Torvalds } 871da177e4SLinus Torvalds 88d5c7409fSTejun Heo /** 89d5c7409fSTejun Heo * idr_layer_alloc - allocate a new idr_layer 90d5c7409fSTejun Heo * @gfp_mask: allocation mask 91d5c7409fSTejun Heo * @layer_idr: optional idr to allocate from 92d5c7409fSTejun Heo * 93d5c7409fSTejun Heo * If @layer_idr is %NULL, directly allocate one using @gfp_mask or fetch 94d5c7409fSTejun Heo * one from the per-cpu preload buffer. If @layer_idr is not %NULL, fetch 95d5c7409fSTejun Heo * an idr_layer from @idr->id_free. 96d5c7409fSTejun Heo * 97d5c7409fSTejun Heo * @layer_idr is to maintain backward compatibility with the old alloc 98d5c7409fSTejun Heo * interface - idr_pre_get() and idr_get_new*() - and will be removed 99d5c7409fSTejun Heo * together with per-pool preload buffer. 100d5c7409fSTejun Heo */ 101d5c7409fSTejun Heo static struct idr_layer *idr_layer_alloc(gfp_t gfp_mask, struct idr *layer_idr) 102d5c7409fSTejun Heo { 103d5c7409fSTejun Heo struct idr_layer *new; 104d5c7409fSTejun Heo 105d5c7409fSTejun Heo /* this is the old path, bypass to get_from_free_list() */ 106d5c7409fSTejun Heo if (layer_idr) 107d5c7409fSTejun Heo return get_from_free_list(layer_idr); 108d5c7409fSTejun Heo 109d5c7409fSTejun Heo /* try to allocate directly from kmem_cache */ 110d5c7409fSTejun Heo new = kmem_cache_zalloc(idr_layer_cache, gfp_mask); 111d5c7409fSTejun Heo if (new) 112d5c7409fSTejun Heo return new; 113d5c7409fSTejun Heo 114d5c7409fSTejun Heo /* 115d5c7409fSTejun Heo * Try to fetch one from the per-cpu preload buffer if in process 116d5c7409fSTejun Heo * context. See idr_preload() for details. 117d5c7409fSTejun Heo */ 118d5c7409fSTejun Heo if (in_interrupt()) 119d5c7409fSTejun Heo return NULL; 120d5c7409fSTejun Heo 121d5c7409fSTejun Heo preempt_disable(); 122d5c7409fSTejun Heo new = __this_cpu_read(idr_preload_head); 123d5c7409fSTejun Heo if (new) { 124d5c7409fSTejun Heo __this_cpu_write(idr_preload_head, new->ary[0]); 125d5c7409fSTejun Heo __this_cpu_dec(idr_preload_cnt); 126d5c7409fSTejun Heo new->ary[0] = NULL; 127d5c7409fSTejun Heo } 128d5c7409fSTejun Heo preempt_enable(); 129d5c7409fSTejun Heo return new; 130d5c7409fSTejun Heo } 131d5c7409fSTejun Heo 132cf481c20SNadia Derbey static void idr_layer_rcu_free(struct rcu_head *head) 133cf481c20SNadia Derbey { 134cf481c20SNadia Derbey struct idr_layer *layer; 135cf481c20SNadia Derbey 136cf481c20SNadia Derbey layer = container_of(head, struct idr_layer, rcu_head); 137cf481c20SNadia Derbey kmem_cache_free(idr_layer_cache, layer); 138cf481c20SNadia Derbey } 139cf481c20SNadia Derbey 1400ffc2a9cSTejun Heo static inline void free_layer(struct idr *idr, struct idr_layer *p) 141cf481c20SNadia Derbey { 1420ffc2a9cSTejun Heo if (idr->hint && idr->hint == p) 1430ffc2a9cSTejun Heo RCU_INIT_POINTER(idr->hint, NULL); 144cf481c20SNadia Derbey call_rcu(&p->rcu_head, idr_layer_rcu_free); 145cf481c20SNadia Derbey } 146cf481c20SNadia Derbey 1471eec0056SSonny Rao /* only called when idp->lock is held */ 1484ae53789SNadia Derbey static void __move_to_free_list(struct idr *idp, struct idr_layer *p) 1491eec0056SSonny Rao { 1501eec0056SSonny Rao p->ary[0] = idp->id_free; 1511eec0056SSonny Rao idp->id_free = p; 1521eec0056SSonny Rao idp->id_free_cnt++; 1531eec0056SSonny Rao } 1541eec0056SSonny Rao 1554ae53789SNadia Derbey static void move_to_free_list(struct idr *idp, struct idr_layer *p) 1561da177e4SLinus Torvalds { 157c259cc28SRoland Dreier unsigned long flags; 158c259cc28SRoland Dreier 1591da177e4SLinus Torvalds /* 1601da177e4SLinus Torvalds * Depends on the return element being zeroed. 1611da177e4SLinus Torvalds */ 162c259cc28SRoland Dreier spin_lock_irqsave(&idp->lock, flags); 1634ae53789SNadia Derbey __move_to_free_list(idp, p); 164c259cc28SRoland Dreier spin_unlock_irqrestore(&idp->lock, flags); 1651da177e4SLinus Torvalds } 1661da177e4SLinus Torvalds 167e33ac8bdSTejun Heo static void idr_mark_full(struct idr_layer **pa, int id) 168e33ac8bdSTejun Heo { 169e33ac8bdSTejun Heo struct idr_layer *p = pa[0]; 170e33ac8bdSTejun Heo int l = 0; 171e33ac8bdSTejun Heo 1721d9b2e1eSTejun Heo __set_bit(id & IDR_MASK, p->bitmap); 173e33ac8bdSTejun Heo /* 174e33ac8bdSTejun Heo * If this layer is full mark the bit in the layer above to 175e33ac8bdSTejun Heo * show that this part of the radix tree is full. This may 176e33ac8bdSTejun Heo * complete the layer above and require walking up the radix 177e33ac8bdSTejun Heo * tree. 178e33ac8bdSTejun Heo */ 1791d9b2e1eSTejun Heo while (bitmap_full(p->bitmap, IDR_SIZE)) { 180e33ac8bdSTejun Heo if (!(p = pa[++l])) 181e33ac8bdSTejun Heo break; 182e33ac8bdSTejun Heo id = id >> IDR_BITS; 1831d9b2e1eSTejun Heo __set_bit((id & IDR_MASK), p->bitmap); 184e33ac8bdSTejun Heo } 185e33ac8bdSTejun Heo } 186e33ac8bdSTejun Heo 187c8615d37STejun Heo int __idr_pre_get(struct idr *idp, gfp_t gfp_mask) 1881da177e4SLinus Torvalds { 189125c4c70SFengguang Wu while (idp->id_free_cnt < MAX_IDR_FREE) { 1901da177e4SLinus Torvalds struct idr_layer *new; 1915b019e99SAndrew Morton new = kmem_cache_zalloc(idr_layer_cache, gfp_mask); 1921da177e4SLinus Torvalds if (new == NULL) 1931da177e4SLinus Torvalds return (0); 1944ae53789SNadia Derbey move_to_free_list(idp, new); 1951da177e4SLinus Torvalds } 1961da177e4SLinus Torvalds return 1; 1971da177e4SLinus Torvalds } 198c8615d37STejun Heo EXPORT_SYMBOL(__idr_pre_get); 1991da177e4SLinus Torvalds 20012d1b439STejun Heo /** 20112d1b439STejun Heo * sub_alloc - try to allocate an id without growing the tree depth 20212d1b439STejun Heo * @idp: idr handle 20312d1b439STejun Heo * @starting_id: id to start search at 20412d1b439STejun Heo * @pa: idr_layer[MAX_IDR_LEVEL] used as backtrack buffer 205d5c7409fSTejun Heo * @gfp_mask: allocation mask for idr_layer_alloc() 206d5c7409fSTejun Heo * @layer_idr: optional idr passed to idr_layer_alloc() 20712d1b439STejun Heo * 20812d1b439STejun Heo * Allocate an id in range [@starting_id, INT_MAX] from @idp without 20912d1b439STejun Heo * growing its depth. Returns 21012d1b439STejun Heo * 21112d1b439STejun Heo * the allocated id >= 0 if successful, 21212d1b439STejun Heo * -EAGAIN if the tree needs to grow for allocation to succeed, 21312d1b439STejun Heo * -ENOSPC if the id space is exhausted, 21412d1b439STejun Heo * -ENOMEM if more idr_layers need to be allocated. 21512d1b439STejun Heo */ 216d5c7409fSTejun Heo static int sub_alloc(struct idr *idp, int *starting_id, struct idr_layer **pa, 217d5c7409fSTejun Heo gfp_t gfp_mask, struct idr *layer_idr) 2181da177e4SLinus Torvalds { 2191da177e4SLinus Torvalds int n, m, sh; 2201da177e4SLinus Torvalds struct idr_layer *p, *new; 2217aae6dd8STejun Heo int l, id, oid; 2221da177e4SLinus Torvalds 2231da177e4SLinus Torvalds id = *starting_id; 2247aae6dd8STejun Heo restart: 2251da177e4SLinus Torvalds p = idp->top; 2261da177e4SLinus Torvalds l = idp->layers; 2271da177e4SLinus Torvalds pa[l--] = NULL; 2281da177e4SLinus Torvalds while (1) { 2291da177e4SLinus Torvalds /* 2301da177e4SLinus Torvalds * We run around this while until we reach the leaf node... 2311da177e4SLinus Torvalds */ 2321da177e4SLinus Torvalds n = (id >> (IDR_BITS*l)) & IDR_MASK; 2331d9b2e1eSTejun Heo m = find_next_zero_bit(p->bitmap, IDR_SIZE, n); 2341da177e4SLinus Torvalds if (m == IDR_SIZE) { 2351da177e4SLinus Torvalds /* no space available go back to previous layer. */ 2361da177e4SLinus Torvalds l++; 2377aae6dd8STejun Heo oid = id; 2381da177e4SLinus Torvalds id = (id | ((1 << (IDR_BITS * l)) - 1)) + 1; 2397aae6dd8STejun Heo 2407aae6dd8STejun Heo /* if already at the top layer, we need to grow */ 241d2e7276bSTejun Heo if (id >= 1 << (idp->layers * IDR_BITS)) { 2421da177e4SLinus Torvalds *starting_id = id; 24312d1b439STejun Heo return -EAGAIN; 2441da177e4SLinus Torvalds } 245d2e7276bSTejun Heo p = pa[l]; 246d2e7276bSTejun Heo BUG_ON(!p); 2477aae6dd8STejun Heo 2487aae6dd8STejun Heo /* If we need to go up one layer, continue the 2497aae6dd8STejun Heo * loop; otherwise, restart from the top. 2507aae6dd8STejun Heo */ 2517aae6dd8STejun Heo sh = IDR_BITS * (l + 1); 2527aae6dd8STejun Heo if (oid >> sh == id >> sh) 2531da177e4SLinus Torvalds continue; 2547aae6dd8STejun Heo else 2557aae6dd8STejun Heo goto restart; 2561da177e4SLinus Torvalds } 2571da177e4SLinus Torvalds if (m != n) { 2581da177e4SLinus Torvalds sh = IDR_BITS*l; 2591da177e4SLinus Torvalds id = ((id >> sh) ^ n ^ m) << sh; 2601da177e4SLinus Torvalds } 261125c4c70SFengguang Wu if ((id >= MAX_IDR_BIT) || (id < 0)) 26212d1b439STejun Heo return -ENOSPC; 2631da177e4SLinus Torvalds if (l == 0) 2641da177e4SLinus Torvalds break; 2651da177e4SLinus Torvalds /* 2661da177e4SLinus Torvalds * Create the layer below if it is missing. 2671da177e4SLinus Torvalds */ 2681da177e4SLinus Torvalds if (!p->ary[m]) { 269d5c7409fSTejun Heo new = idr_layer_alloc(gfp_mask, layer_idr); 2704ae53789SNadia Derbey if (!new) 27112d1b439STejun Heo return -ENOMEM; 2726ff2d39bSManfred Spraul new->layer = l-1; 27354616283STejun Heo new->prefix = id & idr_layer_prefix_mask(new->layer); 2743219b3b7SNadia Derbey rcu_assign_pointer(p->ary[m], new); 2751da177e4SLinus Torvalds p->count++; 2761da177e4SLinus Torvalds } 2771da177e4SLinus Torvalds pa[l--] = p; 2781da177e4SLinus Torvalds p = p->ary[m]; 2791da177e4SLinus Torvalds } 280e33ac8bdSTejun Heo 281e33ac8bdSTejun Heo pa[l] = p; 282e33ac8bdSTejun Heo return id; 2831da177e4SLinus Torvalds } 2841da177e4SLinus Torvalds 285e33ac8bdSTejun Heo static int idr_get_empty_slot(struct idr *idp, int starting_id, 286d5c7409fSTejun Heo struct idr_layer **pa, gfp_t gfp_mask, 287d5c7409fSTejun Heo struct idr *layer_idr) 2881da177e4SLinus Torvalds { 2891da177e4SLinus Torvalds struct idr_layer *p, *new; 2901da177e4SLinus Torvalds int layers, v, id; 291c259cc28SRoland Dreier unsigned long flags; 2921da177e4SLinus Torvalds 2931da177e4SLinus Torvalds id = starting_id; 2941da177e4SLinus Torvalds build_up: 2951da177e4SLinus Torvalds p = idp->top; 2961da177e4SLinus Torvalds layers = idp->layers; 2971da177e4SLinus Torvalds if (unlikely(!p)) { 298d5c7409fSTejun Heo if (!(p = idr_layer_alloc(gfp_mask, layer_idr))) 29912d1b439STejun Heo return -ENOMEM; 3006ff2d39bSManfred Spraul p->layer = 0; 3011da177e4SLinus Torvalds layers = 1; 3021da177e4SLinus Torvalds } 3031da177e4SLinus Torvalds /* 3041da177e4SLinus Torvalds * Add a new layer to the top of the tree if the requested 3051da177e4SLinus Torvalds * id is larger than the currently allocated space. 3061da177e4SLinus Torvalds */ 307326cf0f0STejun Heo while (id > idr_max(layers)) { 3081da177e4SLinus Torvalds layers++; 309711a49a0SManfred Spraul if (!p->count) { 310711a49a0SManfred Spraul /* special case: if the tree is currently empty, 311711a49a0SManfred Spraul * then we grow the tree by moving the top node 312711a49a0SManfred Spraul * upwards. 313711a49a0SManfred Spraul */ 314711a49a0SManfred Spraul p->layer++; 31554616283STejun Heo WARN_ON_ONCE(p->prefix); 3161da177e4SLinus Torvalds continue; 317711a49a0SManfred Spraul } 318d5c7409fSTejun Heo if (!(new = idr_layer_alloc(gfp_mask, layer_idr))) { 3191da177e4SLinus Torvalds /* 3201da177e4SLinus Torvalds * The allocation failed. If we built part of 3211da177e4SLinus Torvalds * the structure tear it down. 3221da177e4SLinus Torvalds */ 323c259cc28SRoland Dreier spin_lock_irqsave(&idp->lock, flags); 3241da177e4SLinus Torvalds for (new = p; p && p != idp->top; new = p) { 3251da177e4SLinus Torvalds p = p->ary[0]; 3261da177e4SLinus Torvalds new->ary[0] = NULL; 3271d9b2e1eSTejun Heo new->count = 0; 3281d9b2e1eSTejun Heo bitmap_clear(new->bitmap, 0, IDR_SIZE); 3294ae53789SNadia Derbey __move_to_free_list(idp, new); 3301da177e4SLinus Torvalds } 331c259cc28SRoland Dreier spin_unlock_irqrestore(&idp->lock, flags); 33212d1b439STejun Heo return -ENOMEM; 3331da177e4SLinus Torvalds } 3341da177e4SLinus Torvalds new->ary[0] = p; 3351da177e4SLinus Torvalds new->count = 1; 3366ff2d39bSManfred Spraul new->layer = layers-1; 33754616283STejun Heo new->prefix = id & idr_layer_prefix_mask(new->layer); 3381d9b2e1eSTejun Heo if (bitmap_full(p->bitmap, IDR_SIZE)) 3391d9b2e1eSTejun Heo __set_bit(0, new->bitmap); 3401da177e4SLinus Torvalds p = new; 3411da177e4SLinus Torvalds } 3423219b3b7SNadia Derbey rcu_assign_pointer(idp->top, p); 3431da177e4SLinus Torvalds idp->layers = layers; 344d5c7409fSTejun Heo v = sub_alloc(idp, &id, pa, gfp_mask, layer_idr); 34512d1b439STejun Heo if (v == -EAGAIN) 3461da177e4SLinus Torvalds goto build_up; 3471da177e4SLinus Torvalds return(v); 3481da177e4SLinus Torvalds } 3491da177e4SLinus Torvalds 350e33ac8bdSTejun Heo /* 3513594eb28STejun Heo * @id and @pa are from a successful allocation from idr_get_empty_slot(). 3523594eb28STejun Heo * Install the user pointer @ptr and mark the slot full. 353e33ac8bdSTejun Heo */ 3540ffc2a9cSTejun Heo static void idr_fill_slot(struct idr *idr, void *ptr, int id, 3550ffc2a9cSTejun Heo struct idr_layer **pa) 3563594eb28STejun Heo { 3570ffc2a9cSTejun Heo /* update hint used for lookup, cleared from free_layer() */ 3580ffc2a9cSTejun Heo rcu_assign_pointer(idr->hint, pa[0]); 3590ffc2a9cSTejun Heo 3603594eb28STejun Heo rcu_assign_pointer(pa[0]->ary[id & IDR_MASK], (struct idr_layer *)ptr); 361e33ac8bdSTejun Heo pa[0]->count++; 362e33ac8bdSTejun Heo idr_mark_full(pa, id); 363e33ac8bdSTejun Heo } 364e33ac8bdSTejun Heo 365c8615d37STejun Heo int __idr_get_new_above(struct idr *idp, void *ptr, int starting_id, int *id) 3661da177e4SLinus Torvalds { 367326cf0f0STejun Heo struct idr_layer *pa[MAX_IDR_LEVEL + 1]; 3681da177e4SLinus Torvalds int rv; 369e15ae2ddSJesper Juhl 370d5c7409fSTejun Heo rv = idr_get_empty_slot(idp, starting_id, pa, 0, idp); 371944ca05cSNadia Derbey if (rv < 0) 37212d1b439STejun Heo return rv == -ENOMEM ? -EAGAIN : rv; 3733594eb28STejun Heo 3740ffc2a9cSTejun Heo idr_fill_slot(idp, ptr, rv, pa); 3751da177e4SLinus Torvalds *id = rv; 3761da177e4SLinus Torvalds return 0; 3771da177e4SLinus Torvalds } 378c8615d37STejun Heo EXPORT_SYMBOL(__idr_get_new_above); 3791da177e4SLinus Torvalds 380d5c7409fSTejun Heo /** 381d5c7409fSTejun Heo * idr_preload - preload for idr_alloc() 382d5c7409fSTejun Heo * @gfp_mask: allocation mask to use for preloading 383d5c7409fSTejun Heo * 384d5c7409fSTejun Heo * Preload per-cpu layer buffer for idr_alloc(). Can only be used from 385d5c7409fSTejun Heo * process context and each idr_preload() invocation should be matched with 386d5c7409fSTejun Heo * idr_preload_end(). Note that preemption is disabled while preloaded. 387d5c7409fSTejun Heo * 388d5c7409fSTejun Heo * The first idr_alloc() in the preloaded section can be treated as if it 389d5c7409fSTejun Heo * were invoked with @gfp_mask used for preloading. This allows using more 390d5c7409fSTejun Heo * permissive allocation masks for idrs protected by spinlocks. 391d5c7409fSTejun Heo * 392d5c7409fSTejun Heo * For example, if idr_alloc() below fails, the failure can be treated as 393d5c7409fSTejun Heo * if idr_alloc() were called with GFP_KERNEL rather than GFP_NOWAIT. 394d5c7409fSTejun Heo * 395d5c7409fSTejun Heo * idr_preload(GFP_KERNEL); 396d5c7409fSTejun Heo * spin_lock(lock); 397d5c7409fSTejun Heo * 398d5c7409fSTejun Heo * id = idr_alloc(idr, ptr, start, end, GFP_NOWAIT); 399d5c7409fSTejun Heo * 400d5c7409fSTejun Heo * spin_unlock(lock); 401d5c7409fSTejun Heo * idr_preload_end(); 402d5c7409fSTejun Heo * if (id < 0) 403d5c7409fSTejun Heo * error; 404d5c7409fSTejun Heo */ 405d5c7409fSTejun Heo void idr_preload(gfp_t gfp_mask) 406d5c7409fSTejun Heo { 407d5c7409fSTejun Heo /* 408d5c7409fSTejun Heo * Consuming preload buffer from non-process context breaks preload 409d5c7409fSTejun Heo * allocation guarantee. Disallow usage from those contexts. 410d5c7409fSTejun Heo */ 411d5c7409fSTejun Heo WARN_ON_ONCE(in_interrupt()); 412d5c7409fSTejun Heo might_sleep_if(gfp_mask & __GFP_WAIT); 413d5c7409fSTejun Heo 414d5c7409fSTejun Heo preempt_disable(); 415d5c7409fSTejun Heo 416d5c7409fSTejun Heo /* 417d5c7409fSTejun Heo * idr_alloc() is likely to succeed w/o full idr_layer buffer and 418d5c7409fSTejun Heo * return value from idr_alloc() needs to be checked for failure 419d5c7409fSTejun Heo * anyway. Silently give up if allocation fails. The caller can 420d5c7409fSTejun Heo * treat failures from idr_alloc() as if idr_alloc() were called 421d5c7409fSTejun Heo * with @gfp_mask which should be enough. 422d5c7409fSTejun Heo */ 423d5c7409fSTejun Heo while (__this_cpu_read(idr_preload_cnt) < MAX_IDR_FREE) { 424d5c7409fSTejun Heo struct idr_layer *new; 425d5c7409fSTejun Heo 426d5c7409fSTejun Heo preempt_enable(); 427d5c7409fSTejun Heo new = kmem_cache_zalloc(idr_layer_cache, gfp_mask); 428d5c7409fSTejun Heo preempt_disable(); 429d5c7409fSTejun Heo if (!new) 430d5c7409fSTejun Heo break; 431d5c7409fSTejun Heo 432d5c7409fSTejun Heo /* link the new one to per-cpu preload list */ 433d5c7409fSTejun Heo new->ary[0] = __this_cpu_read(idr_preload_head); 434d5c7409fSTejun Heo __this_cpu_write(idr_preload_head, new); 435d5c7409fSTejun Heo __this_cpu_inc(idr_preload_cnt); 436d5c7409fSTejun Heo } 437d5c7409fSTejun Heo } 438d5c7409fSTejun Heo EXPORT_SYMBOL(idr_preload); 439d5c7409fSTejun Heo 440d5c7409fSTejun Heo /** 441d5c7409fSTejun Heo * idr_alloc - allocate new idr entry 442d5c7409fSTejun Heo * @idr: the (initialized) idr 443d5c7409fSTejun Heo * @ptr: pointer to be associated with the new id 444d5c7409fSTejun Heo * @start: the minimum id (inclusive) 445d5c7409fSTejun Heo * @end: the maximum id (exclusive, <= 0 for max) 446d5c7409fSTejun Heo * @gfp_mask: memory allocation flags 447d5c7409fSTejun Heo * 448d5c7409fSTejun Heo * Allocate an id in [start, end) and associate it with @ptr. If no ID is 449d5c7409fSTejun Heo * available in the specified range, returns -ENOSPC. On memory allocation 450d5c7409fSTejun Heo * failure, returns -ENOMEM. 451d5c7409fSTejun Heo * 452d5c7409fSTejun Heo * Note that @end is treated as max when <= 0. This is to always allow 453d5c7409fSTejun Heo * using @start + N as @end as long as N is inside integer range. 454d5c7409fSTejun Heo * 455d5c7409fSTejun Heo * The user is responsible for exclusively synchronizing all operations 456d5c7409fSTejun Heo * which may modify @idr. However, read-only accesses such as idr_find() 457d5c7409fSTejun Heo * or iteration can be performed under RCU read lock provided the user 458d5c7409fSTejun Heo * destroys @ptr in RCU-safe way after removal from idr. 459d5c7409fSTejun Heo */ 460d5c7409fSTejun Heo int idr_alloc(struct idr *idr, void *ptr, int start, int end, gfp_t gfp_mask) 461d5c7409fSTejun Heo { 462d5c7409fSTejun Heo int max = end > 0 ? end - 1 : INT_MAX; /* inclusive upper limit */ 463326cf0f0STejun Heo struct idr_layer *pa[MAX_IDR_LEVEL + 1]; 464d5c7409fSTejun Heo int id; 465d5c7409fSTejun Heo 466d5c7409fSTejun Heo might_sleep_if(gfp_mask & __GFP_WAIT); 467d5c7409fSTejun Heo 468d5c7409fSTejun Heo /* sanity checks */ 469d5c7409fSTejun Heo if (WARN_ON_ONCE(start < 0)) 470d5c7409fSTejun Heo return -EINVAL; 471d5c7409fSTejun Heo if (unlikely(max < start)) 472d5c7409fSTejun Heo return -ENOSPC; 473d5c7409fSTejun Heo 474d5c7409fSTejun Heo /* allocate id */ 475d5c7409fSTejun Heo id = idr_get_empty_slot(idr, start, pa, gfp_mask, NULL); 476d5c7409fSTejun Heo if (unlikely(id < 0)) 477d5c7409fSTejun Heo return id; 478d5c7409fSTejun Heo if (unlikely(id > max)) 479d5c7409fSTejun Heo return -ENOSPC; 480d5c7409fSTejun Heo 4810ffc2a9cSTejun Heo idr_fill_slot(idr, ptr, id, pa); 482d5c7409fSTejun Heo return id; 483d5c7409fSTejun Heo } 484d5c7409fSTejun Heo EXPORT_SYMBOL_GPL(idr_alloc); 485d5c7409fSTejun Heo 4861da177e4SLinus Torvalds static void idr_remove_warning(int id) 4871da177e4SLinus Torvalds { 488f098ad65SNadia Derbey printk(KERN_WARNING 489f098ad65SNadia Derbey "idr_remove called for id=%d which is not allocated.\n", id); 4901da177e4SLinus Torvalds dump_stack(); 4911da177e4SLinus Torvalds } 4921da177e4SLinus Torvalds 4931da177e4SLinus Torvalds static void sub_remove(struct idr *idp, int shift, int id) 4941da177e4SLinus Torvalds { 4951da177e4SLinus Torvalds struct idr_layer *p = idp->top; 496326cf0f0STejun Heo struct idr_layer **pa[MAX_IDR_LEVEL + 1]; 4971da177e4SLinus Torvalds struct idr_layer ***paa = &pa[0]; 498cf481c20SNadia Derbey struct idr_layer *to_free; 4991da177e4SLinus Torvalds int n; 5001da177e4SLinus Torvalds 5011da177e4SLinus Torvalds *paa = NULL; 5021da177e4SLinus Torvalds *++paa = &idp->top; 5031da177e4SLinus Torvalds 5041da177e4SLinus Torvalds while ((shift > 0) && p) { 5051da177e4SLinus Torvalds n = (id >> shift) & IDR_MASK; 5061d9b2e1eSTejun Heo __clear_bit(n, p->bitmap); 5071da177e4SLinus Torvalds *++paa = &p->ary[n]; 5081da177e4SLinus Torvalds p = p->ary[n]; 5091da177e4SLinus Torvalds shift -= IDR_BITS; 5101da177e4SLinus Torvalds } 5111da177e4SLinus Torvalds n = id & IDR_MASK; 5121d9b2e1eSTejun Heo if (likely(p != NULL && test_bit(n, p->bitmap))) { 5131d9b2e1eSTejun Heo __clear_bit(n, p->bitmap); 514cf481c20SNadia Derbey rcu_assign_pointer(p->ary[n], NULL); 515cf481c20SNadia Derbey to_free = NULL; 5161da177e4SLinus Torvalds while(*paa && ! --((**paa)->count)){ 517cf481c20SNadia Derbey if (to_free) 5180ffc2a9cSTejun Heo free_layer(idp, to_free); 519cf481c20SNadia Derbey to_free = **paa; 5201da177e4SLinus Torvalds **paa-- = NULL; 5211da177e4SLinus Torvalds } 5221da177e4SLinus Torvalds if (!*paa) 5231da177e4SLinus Torvalds idp->layers = 0; 524cf481c20SNadia Derbey if (to_free) 5250ffc2a9cSTejun Heo free_layer(idp, to_free); 526e15ae2ddSJesper Juhl } else 5271da177e4SLinus Torvalds idr_remove_warning(id); 5281da177e4SLinus Torvalds } 5291da177e4SLinus Torvalds 5301da177e4SLinus Torvalds /** 53156083ab1SRandy Dunlap * idr_remove - remove the given id and free its slot 53272fd4a35SRobert P. J. Day * @idp: idr handle 53372fd4a35SRobert P. J. Day * @id: unique key 5341da177e4SLinus Torvalds */ 5351da177e4SLinus Torvalds void idr_remove(struct idr *idp, int id) 5361da177e4SLinus Torvalds { 5371da177e4SLinus Torvalds struct idr_layer *p; 538cf481c20SNadia Derbey struct idr_layer *to_free; 5391da177e4SLinus Torvalds 5402e1c9b28STejun Heo if (id < 0) 541e8c8d1bcSTejun Heo return; 5421da177e4SLinus Torvalds 5431da177e4SLinus Torvalds sub_remove(idp, (idp->layers - 1) * IDR_BITS, id); 544e15ae2ddSJesper Juhl if (idp->top && idp->top->count == 1 && (idp->layers > 1) && 545cf481c20SNadia Derbey idp->top->ary[0]) { 546cf481c20SNadia Derbey /* 547cf481c20SNadia Derbey * Single child at leftmost slot: we can shrink the tree. 548cf481c20SNadia Derbey * This level is not needed anymore since when layers are 549cf481c20SNadia Derbey * inserted, they are inserted at the top of the existing 550cf481c20SNadia Derbey * tree. 551cf481c20SNadia Derbey */ 552cf481c20SNadia Derbey to_free = idp->top; 5531da177e4SLinus Torvalds p = idp->top->ary[0]; 554cf481c20SNadia Derbey rcu_assign_pointer(idp->top, p); 5551da177e4SLinus Torvalds --idp->layers; 5561d9b2e1eSTejun Heo to_free->count = 0; 5571d9b2e1eSTejun Heo bitmap_clear(to_free->bitmap, 0, IDR_SIZE); 5580ffc2a9cSTejun Heo free_layer(idp, to_free); 5591da177e4SLinus Torvalds } 560125c4c70SFengguang Wu while (idp->id_free_cnt >= MAX_IDR_FREE) { 5614ae53789SNadia Derbey p = get_from_free_list(idp); 562cf481c20SNadia Derbey /* 563cf481c20SNadia Derbey * Note: we don't call the rcu callback here, since the only 564cf481c20SNadia Derbey * layers that fall into the freelist are those that have been 565cf481c20SNadia Derbey * preallocated. 566cf481c20SNadia Derbey */ 5671da177e4SLinus Torvalds kmem_cache_free(idr_layer_cache, p); 5681da177e4SLinus Torvalds } 569af8e2a4cSNadia Derbey return; 5701da177e4SLinus Torvalds } 5711da177e4SLinus Torvalds EXPORT_SYMBOL(idr_remove); 5721da177e4SLinus Torvalds 573fe6e24ecSTejun Heo void __idr_remove_all(struct idr *idp) 57423936cc0SKristian Hoegsberg { 5756ace06dcSOleg Nesterov int n, id, max; 5762dcb22b3SImre Deak int bt_mask; 57723936cc0SKristian Hoegsberg struct idr_layer *p; 578326cf0f0STejun Heo struct idr_layer *pa[MAX_IDR_LEVEL + 1]; 57923936cc0SKristian Hoegsberg struct idr_layer **paa = &pa[0]; 58023936cc0SKristian Hoegsberg 58123936cc0SKristian Hoegsberg n = idp->layers * IDR_BITS; 58223936cc0SKristian Hoegsberg p = idp->top; 5831b23336aSPaul E. McKenney rcu_assign_pointer(idp->top, NULL); 584326cf0f0STejun Heo max = idr_max(idp->layers); 58523936cc0SKristian Hoegsberg 58623936cc0SKristian Hoegsberg id = 0; 587326cf0f0STejun Heo while (id >= 0 && id <= max) { 58823936cc0SKristian Hoegsberg while (n > IDR_BITS && p) { 58923936cc0SKristian Hoegsberg n -= IDR_BITS; 59023936cc0SKristian Hoegsberg *paa++ = p; 59123936cc0SKristian Hoegsberg p = p->ary[(id >> n) & IDR_MASK]; 59223936cc0SKristian Hoegsberg } 59323936cc0SKristian Hoegsberg 5942dcb22b3SImre Deak bt_mask = id; 59523936cc0SKristian Hoegsberg id += 1 << n; 5962dcb22b3SImre Deak /* Get the highest bit that the above add changed from 0->1. */ 5972dcb22b3SImre Deak while (n < fls(id ^ bt_mask)) { 598cf481c20SNadia Derbey if (p) 5990ffc2a9cSTejun Heo free_layer(idp, p); 60023936cc0SKristian Hoegsberg n += IDR_BITS; 60123936cc0SKristian Hoegsberg p = *--paa; 60223936cc0SKristian Hoegsberg } 60323936cc0SKristian Hoegsberg } 60423936cc0SKristian Hoegsberg idp->layers = 0; 60523936cc0SKristian Hoegsberg } 606fe6e24ecSTejun Heo EXPORT_SYMBOL(__idr_remove_all); 60723936cc0SKristian Hoegsberg 60823936cc0SKristian Hoegsberg /** 6098d3b3591SAndrew Morton * idr_destroy - release all cached layers within an idr tree 610ea24ea85SNaohiro Aota * @idp: idr handle 6119bb26bc1STejun Heo * 6129bb26bc1STejun Heo * Free all id mappings and all idp_layers. After this function, @idp is 6139bb26bc1STejun Heo * completely unused and can be freed / recycled. The caller is 6149bb26bc1STejun Heo * responsible for ensuring that no one else accesses @idp during or after 6159bb26bc1STejun Heo * idr_destroy(). 6169bb26bc1STejun Heo * 6179bb26bc1STejun Heo * A typical clean-up sequence for objects stored in an idr tree will use 6189bb26bc1STejun Heo * idr_for_each() to free all objects, if necessay, then idr_destroy() to 6199bb26bc1STejun Heo * free up the id mappings and cached idr_layers. 6208d3b3591SAndrew Morton */ 6218d3b3591SAndrew Morton void idr_destroy(struct idr *idp) 6228d3b3591SAndrew Morton { 623fe6e24ecSTejun Heo __idr_remove_all(idp); 6249bb26bc1STejun Heo 6258d3b3591SAndrew Morton while (idp->id_free_cnt) { 6264ae53789SNadia Derbey struct idr_layer *p = get_from_free_list(idp); 6278d3b3591SAndrew Morton kmem_cache_free(idr_layer_cache, p); 6288d3b3591SAndrew Morton } 6298d3b3591SAndrew Morton } 6308d3b3591SAndrew Morton EXPORT_SYMBOL(idr_destroy); 6318d3b3591SAndrew Morton 6320ffc2a9cSTejun Heo void *idr_find_slowpath(struct idr *idp, int id) 6331da177e4SLinus Torvalds { 6341da177e4SLinus Torvalds int n; 6351da177e4SLinus Torvalds struct idr_layer *p; 6361da177e4SLinus Torvalds 6372e1c9b28STejun Heo if (id < 0) 638e8c8d1bcSTejun Heo return NULL; 639e8c8d1bcSTejun Heo 64096be753aSPaul E. McKenney p = rcu_dereference_raw(idp->top); 6416ff2d39bSManfred Spraul if (!p) 6426ff2d39bSManfred Spraul return NULL; 6436ff2d39bSManfred Spraul n = (p->layer+1) * IDR_BITS; 6441da177e4SLinus Torvalds 645326cf0f0STejun Heo if (id > idr_max(p->layer + 1)) 6461da177e4SLinus Torvalds return NULL; 6476ff2d39bSManfred Spraul BUG_ON(n == 0); 6481da177e4SLinus Torvalds 6491da177e4SLinus Torvalds while (n > 0 && p) { 6501da177e4SLinus Torvalds n -= IDR_BITS; 6516ff2d39bSManfred Spraul BUG_ON(n != p->layer*IDR_BITS); 65296be753aSPaul E. McKenney p = rcu_dereference_raw(p->ary[(id >> n) & IDR_MASK]); 6531da177e4SLinus Torvalds } 6541da177e4SLinus Torvalds return((void *)p); 6551da177e4SLinus Torvalds } 6560ffc2a9cSTejun Heo EXPORT_SYMBOL(idr_find_slowpath); 6571da177e4SLinus Torvalds 6585806f07cSJeff Mahoney /** 65996d7fa42SKristian Hoegsberg * idr_for_each - iterate through all stored pointers 66096d7fa42SKristian Hoegsberg * @idp: idr handle 66196d7fa42SKristian Hoegsberg * @fn: function to be called for each pointer 66296d7fa42SKristian Hoegsberg * @data: data passed back to callback function 66396d7fa42SKristian Hoegsberg * 66496d7fa42SKristian Hoegsberg * Iterate over the pointers registered with the given idr. The 66596d7fa42SKristian Hoegsberg * callback function will be called for each pointer currently 66696d7fa42SKristian Hoegsberg * registered, passing the id, the pointer and the data pointer passed 66796d7fa42SKristian Hoegsberg * to this function. It is not safe to modify the idr tree while in 66896d7fa42SKristian Hoegsberg * the callback, so functions such as idr_get_new and idr_remove are 66996d7fa42SKristian Hoegsberg * not allowed. 67096d7fa42SKristian Hoegsberg * 67196d7fa42SKristian Hoegsberg * We check the return of @fn each time. If it returns anything other 67256083ab1SRandy Dunlap * than %0, we break out and return that value. 67396d7fa42SKristian Hoegsberg * 67496d7fa42SKristian Hoegsberg * The caller must serialize idr_for_each() vs idr_get_new() and idr_remove(). 67596d7fa42SKristian Hoegsberg */ 67696d7fa42SKristian Hoegsberg int idr_for_each(struct idr *idp, 67796d7fa42SKristian Hoegsberg int (*fn)(int id, void *p, void *data), void *data) 67896d7fa42SKristian Hoegsberg { 67996d7fa42SKristian Hoegsberg int n, id, max, error = 0; 68096d7fa42SKristian Hoegsberg struct idr_layer *p; 681326cf0f0STejun Heo struct idr_layer *pa[MAX_IDR_LEVEL + 1]; 68296d7fa42SKristian Hoegsberg struct idr_layer **paa = &pa[0]; 68396d7fa42SKristian Hoegsberg 68496d7fa42SKristian Hoegsberg n = idp->layers * IDR_BITS; 68596be753aSPaul E. McKenney p = rcu_dereference_raw(idp->top); 686326cf0f0STejun Heo max = idr_max(idp->layers); 68796d7fa42SKristian Hoegsberg 68896d7fa42SKristian Hoegsberg id = 0; 689326cf0f0STejun Heo while (id >= 0 && id <= max) { 69096d7fa42SKristian Hoegsberg while (n > 0 && p) { 69196d7fa42SKristian Hoegsberg n -= IDR_BITS; 69296d7fa42SKristian Hoegsberg *paa++ = p; 69396be753aSPaul E. McKenney p = rcu_dereference_raw(p->ary[(id >> n) & IDR_MASK]); 69496d7fa42SKristian Hoegsberg } 69596d7fa42SKristian Hoegsberg 69696d7fa42SKristian Hoegsberg if (p) { 69796d7fa42SKristian Hoegsberg error = fn(id, (void *)p, data); 69896d7fa42SKristian Hoegsberg if (error) 69996d7fa42SKristian Hoegsberg break; 70096d7fa42SKristian Hoegsberg } 70196d7fa42SKristian Hoegsberg 70296d7fa42SKristian Hoegsberg id += 1 << n; 70396d7fa42SKristian Hoegsberg while (n < fls(id)) { 70496d7fa42SKristian Hoegsberg n += IDR_BITS; 70596d7fa42SKristian Hoegsberg p = *--paa; 70696d7fa42SKristian Hoegsberg } 70796d7fa42SKristian Hoegsberg } 70896d7fa42SKristian Hoegsberg 70996d7fa42SKristian Hoegsberg return error; 71096d7fa42SKristian Hoegsberg } 71196d7fa42SKristian Hoegsberg EXPORT_SYMBOL(idr_for_each); 71296d7fa42SKristian Hoegsberg 71396d7fa42SKristian Hoegsberg /** 71438460b48SKAMEZAWA Hiroyuki * idr_get_next - lookup next object of id to given id. 71538460b48SKAMEZAWA Hiroyuki * @idp: idr handle 716ea24ea85SNaohiro Aota * @nextidp: pointer to lookup key 71738460b48SKAMEZAWA Hiroyuki * 71838460b48SKAMEZAWA Hiroyuki * Returns pointer to registered object with id, which is next number to 7191458ce16SNaohiro Aota * given id. After being looked up, *@nextidp will be updated for the next 7201458ce16SNaohiro Aota * iteration. 7219f7de827SHugh Dickins * 7229f7de827SHugh Dickins * This function can be called under rcu_read_lock(), given that the leaf 7239f7de827SHugh Dickins * pointers lifetimes are correctly managed. 72438460b48SKAMEZAWA Hiroyuki */ 72538460b48SKAMEZAWA Hiroyuki void *idr_get_next(struct idr *idp, int *nextidp) 72638460b48SKAMEZAWA Hiroyuki { 727326cf0f0STejun Heo struct idr_layer *p, *pa[MAX_IDR_LEVEL + 1]; 72838460b48SKAMEZAWA Hiroyuki struct idr_layer **paa = &pa[0]; 72938460b48SKAMEZAWA Hiroyuki int id = *nextidp; 73038460b48SKAMEZAWA Hiroyuki int n, max; 73138460b48SKAMEZAWA Hiroyuki 73238460b48SKAMEZAWA Hiroyuki /* find first ent */ 73394bfa3b6SPaul E. McKenney p = rcu_dereference_raw(idp->top); 73438460b48SKAMEZAWA Hiroyuki if (!p) 73538460b48SKAMEZAWA Hiroyuki return NULL; 7369f7de827SHugh Dickins n = (p->layer + 1) * IDR_BITS; 737326cf0f0STejun Heo max = idr_max(p->layer + 1); 73838460b48SKAMEZAWA Hiroyuki 739326cf0f0STejun Heo while (id >= 0 && id <= max) { 74038460b48SKAMEZAWA Hiroyuki while (n > 0 && p) { 74138460b48SKAMEZAWA Hiroyuki n -= IDR_BITS; 74238460b48SKAMEZAWA Hiroyuki *paa++ = p; 74394bfa3b6SPaul E. McKenney p = rcu_dereference_raw(p->ary[(id >> n) & IDR_MASK]); 74438460b48SKAMEZAWA Hiroyuki } 74538460b48SKAMEZAWA Hiroyuki 74638460b48SKAMEZAWA Hiroyuki if (p) { 74738460b48SKAMEZAWA Hiroyuki *nextidp = id; 74838460b48SKAMEZAWA Hiroyuki return p; 74938460b48SKAMEZAWA Hiroyuki } 75038460b48SKAMEZAWA Hiroyuki 7516cdae741STejun Heo /* 7526cdae741STejun Heo * Proceed to the next layer at the current level. Unlike 7536cdae741STejun Heo * idr_for_each(), @id isn't guaranteed to be aligned to 7546cdae741STejun Heo * layer boundary at this point and adding 1 << n may 7556cdae741STejun Heo * incorrectly skip IDs. Make sure we jump to the 7566cdae741STejun Heo * beginning of the next layer using round_up(). 7576cdae741STejun Heo */ 7586cdae741STejun Heo id = round_up(id + 1, 1 << n); 75938460b48SKAMEZAWA Hiroyuki while (n < fls(id)) { 76038460b48SKAMEZAWA Hiroyuki n += IDR_BITS; 76138460b48SKAMEZAWA Hiroyuki p = *--paa; 76238460b48SKAMEZAWA Hiroyuki } 76338460b48SKAMEZAWA Hiroyuki } 76438460b48SKAMEZAWA Hiroyuki return NULL; 76538460b48SKAMEZAWA Hiroyuki } 7664d1ee80fSBen Hutchings EXPORT_SYMBOL(idr_get_next); 76738460b48SKAMEZAWA Hiroyuki 76838460b48SKAMEZAWA Hiroyuki 76938460b48SKAMEZAWA Hiroyuki /** 7705806f07cSJeff Mahoney * idr_replace - replace pointer for given id 7715806f07cSJeff Mahoney * @idp: idr handle 7725806f07cSJeff Mahoney * @ptr: pointer you want associated with the id 7735806f07cSJeff Mahoney * @id: lookup key 7745806f07cSJeff Mahoney * 7755806f07cSJeff Mahoney * Replace the pointer registered with an id and return the old value. 77656083ab1SRandy Dunlap * A %-ENOENT return indicates that @id was not found. 77756083ab1SRandy Dunlap * A %-EINVAL return indicates that @id was not within valid constraints. 7785806f07cSJeff Mahoney * 779cf481c20SNadia Derbey * The caller must serialize with writers. 7805806f07cSJeff Mahoney */ 7815806f07cSJeff Mahoney void *idr_replace(struct idr *idp, void *ptr, int id) 7825806f07cSJeff Mahoney { 7835806f07cSJeff Mahoney int n; 7845806f07cSJeff Mahoney struct idr_layer *p, *old_p; 7855806f07cSJeff Mahoney 7862e1c9b28STejun Heo if (id < 0) 787e8c8d1bcSTejun Heo return ERR_PTR(-EINVAL); 788e8c8d1bcSTejun Heo 7895806f07cSJeff Mahoney p = idp->top; 7906ff2d39bSManfred Spraul if (!p) 7916ff2d39bSManfred Spraul return ERR_PTR(-EINVAL); 7926ff2d39bSManfred Spraul 7936ff2d39bSManfred Spraul n = (p->layer+1) * IDR_BITS; 7945806f07cSJeff Mahoney 7955806f07cSJeff Mahoney if (id >= (1 << n)) 7965806f07cSJeff Mahoney return ERR_PTR(-EINVAL); 7975806f07cSJeff Mahoney 7985806f07cSJeff Mahoney n -= IDR_BITS; 7995806f07cSJeff Mahoney while ((n > 0) && p) { 8005806f07cSJeff Mahoney p = p->ary[(id >> n) & IDR_MASK]; 8015806f07cSJeff Mahoney n -= IDR_BITS; 8025806f07cSJeff Mahoney } 8035806f07cSJeff Mahoney 8045806f07cSJeff Mahoney n = id & IDR_MASK; 8051d9b2e1eSTejun Heo if (unlikely(p == NULL || !test_bit(n, p->bitmap))) 8065806f07cSJeff Mahoney return ERR_PTR(-ENOENT); 8075806f07cSJeff Mahoney 8085806f07cSJeff Mahoney old_p = p->ary[n]; 809cf481c20SNadia Derbey rcu_assign_pointer(p->ary[n], ptr); 8105806f07cSJeff Mahoney 8115806f07cSJeff Mahoney return old_p; 8125806f07cSJeff Mahoney } 8135806f07cSJeff Mahoney EXPORT_SYMBOL(idr_replace); 8145806f07cSJeff Mahoney 815199f0ca5SAkinobu Mita void __init idr_init_cache(void) 8161da177e4SLinus Torvalds { 8171da177e4SLinus Torvalds idr_layer_cache = kmem_cache_create("idr_layer_cache", 8185b019e99SAndrew Morton sizeof(struct idr_layer), 0, SLAB_PANIC, NULL); 8191da177e4SLinus Torvalds } 8201da177e4SLinus Torvalds 8211da177e4SLinus Torvalds /** 8221da177e4SLinus Torvalds * idr_init - initialize idr handle 8231da177e4SLinus Torvalds * @idp: idr handle 8241da177e4SLinus Torvalds * 8251da177e4SLinus Torvalds * This function is use to set up the handle (@idp) that you will pass 8261da177e4SLinus Torvalds * to the rest of the functions. 8271da177e4SLinus Torvalds */ 8281da177e4SLinus Torvalds void idr_init(struct idr *idp) 8291da177e4SLinus Torvalds { 8301da177e4SLinus Torvalds memset(idp, 0, sizeof(struct idr)); 8311da177e4SLinus Torvalds spin_lock_init(&idp->lock); 8321da177e4SLinus Torvalds } 8331da177e4SLinus Torvalds EXPORT_SYMBOL(idr_init); 83472dba584STejun Heo 83572dba584STejun Heo 83656083ab1SRandy Dunlap /** 83756083ab1SRandy Dunlap * DOC: IDA description 83872dba584STejun Heo * IDA - IDR based ID allocator 83972dba584STejun Heo * 84056083ab1SRandy Dunlap * This is id allocator without id -> pointer translation. Memory 84172dba584STejun Heo * usage is much lower than full blown idr because each id only 84272dba584STejun Heo * occupies a bit. ida uses a custom leaf node which contains 84372dba584STejun Heo * IDA_BITMAP_BITS slots. 84472dba584STejun Heo * 84572dba584STejun Heo * 2007-04-25 written by Tejun Heo <htejun@gmail.com> 84672dba584STejun Heo */ 84772dba584STejun Heo 84872dba584STejun Heo static void free_bitmap(struct ida *ida, struct ida_bitmap *bitmap) 84972dba584STejun Heo { 85072dba584STejun Heo unsigned long flags; 85172dba584STejun Heo 85272dba584STejun Heo if (!ida->free_bitmap) { 85372dba584STejun Heo spin_lock_irqsave(&ida->idr.lock, flags); 85472dba584STejun Heo if (!ida->free_bitmap) { 85572dba584STejun Heo ida->free_bitmap = bitmap; 85672dba584STejun Heo bitmap = NULL; 85772dba584STejun Heo } 85872dba584STejun Heo spin_unlock_irqrestore(&ida->idr.lock, flags); 85972dba584STejun Heo } 86072dba584STejun Heo 86172dba584STejun Heo kfree(bitmap); 86272dba584STejun Heo } 86372dba584STejun Heo 86472dba584STejun Heo /** 86572dba584STejun Heo * ida_pre_get - reserve resources for ida allocation 86672dba584STejun Heo * @ida: ida handle 86772dba584STejun Heo * @gfp_mask: memory allocation flag 86872dba584STejun Heo * 86972dba584STejun Heo * This function should be called prior to locking and calling the 87072dba584STejun Heo * following function. It preallocates enough memory to satisfy the 87172dba584STejun Heo * worst possible allocation. 87272dba584STejun Heo * 87356083ab1SRandy Dunlap * If the system is REALLY out of memory this function returns %0, 87456083ab1SRandy Dunlap * otherwise %1. 87572dba584STejun Heo */ 87672dba584STejun Heo int ida_pre_get(struct ida *ida, gfp_t gfp_mask) 87772dba584STejun Heo { 87872dba584STejun Heo /* allocate idr_layers */ 879c8615d37STejun Heo if (!__idr_pre_get(&ida->idr, gfp_mask)) 88072dba584STejun Heo return 0; 88172dba584STejun Heo 88272dba584STejun Heo /* allocate free_bitmap */ 88372dba584STejun Heo if (!ida->free_bitmap) { 88472dba584STejun Heo struct ida_bitmap *bitmap; 88572dba584STejun Heo 88672dba584STejun Heo bitmap = kmalloc(sizeof(struct ida_bitmap), gfp_mask); 88772dba584STejun Heo if (!bitmap) 88872dba584STejun Heo return 0; 88972dba584STejun Heo 89072dba584STejun Heo free_bitmap(ida, bitmap); 89172dba584STejun Heo } 89272dba584STejun Heo 89372dba584STejun Heo return 1; 89472dba584STejun Heo } 89572dba584STejun Heo EXPORT_SYMBOL(ida_pre_get); 89672dba584STejun Heo 89772dba584STejun Heo /** 89872dba584STejun Heo * ida_get_new_above - allocate new ID above or equal to a start id 89972dba584STejun Heo * @ida: ida handle 900ea24ea85SNaohiro Aota * @starting_id: id to start search at 90172dba584STejun Heo * @p_id: pointer to the allocated handle 90272dba584STejun Heo * 903e3816c54SWang Sheng-Hui * Allocate new ID above or equal to @starting_id. It should be called 904e3816c54SWang Sheng-Hui * with any required locks. 90572dba584STejun Heo * 90656083ab1SRandy Dunlap * If memory is required, it will return %-EAGAIN, you should unlock 90772dba584STejun Heo * and go back to the ida_pre_get() call. If the ida is full, it will 90856083ab1SRandy Dunlap * return %-ENOSPC. 90972dba584STejun Heo * 91056083ab1SRandy Dunlap * @p_id returns a value in the range @starting_id ... %0x7fffffff. 91172dba584STejun Heo */ 91272dba584STejun Heo int ida_get_new_above(struct ida *ida, int starting_id, int *p_id) 91372dba584STejun Heo { 914326cf0f0STejun Heo struct idr_layer *pa[MAX_IDR_LEVEL + 1]; 91572dba584STejun Heo struct ida_bitmap *bitmap; 91672dba584STejun Heo unsigned long flags; 91772dba584STejun Heo int idr_id = starting_id / IDA_BITMAP_BITS; 91872dba584STejun Heo int offset = starting_id % IDA_BITMAP_BITS; 91972dba584STejun Heo int t, id; 92072dba584STejun Heo 92172dba584STejun Heo restart: 92272dba584STejun Heo /* get vacant slot */ 923d5c7409fSTejun Heo t = idr_get_empty_slot(&ida->idr, idr_id, pa, 0, &ida->idr); 924944ca05cSNadia Derbey if (t < 0) 92512d1b439STejun Heo return t == -ENOMEM ? -EAGAIN : t; 92672dba584STejun Heo 927125c4c70SFengguang Wu if (t * IDA_BITMAP_BITS >= MAX_IDR_BIT) 92872dba584STejun Heo return -ENOSPC; 92972dba584STejun Heo 93072dba584STejun Heo if (t != idr_id) 93172dba584STejun Heo offset = 0; 93272dba584STejun Heo idr_id = t; 93372dba584STejun Heo 93472dba584STejun Heo /* if bitmap isn't there, create a new one */ 93572dba584STejun Heo bitmap = (void *)pa[0]->ary[idr_id & IDR_MASK]; 93672dba584STejun Heo if (!bitmap) { 93772dba584STejun Heo spin_lock_irqsave(&ida->idr.lock, flags); 93872dba584STejun Heo bitmap = ida->free_bitmap; 93972dba584STejun Heo ida->free_bitmap = NULL; 94072dba584STejun Heo spin_unlock_irqrestore(&ida->idr.lock, flags); 94172dba584STejun Heo 94272dba584STejun Heo if (!bitmap) 94372dba584STejun Heo return -EAGAIN; 94472dba584STejun Heo 94572dba584STejun Heo memset(bitmap, 0, sizeof(struct ida_bitmap)); 9463219b3b7SNadia Derbey rcu_assign_pointer(pa[0]->ary[idr_id & IDR_MASK], 9473219b3b7SNadia Derbey (void *)bitmap); 94872dba584STejun Heo pa[0]->count++; 94972dba584STejun Heo } 95072dba584STejun Heo 95172dba584STejun Heo /* lookup for empty slot */ 95272dba584STejun Heo t = find_next_zero_bit(bitmap->bitmap, IDA_BITMAP_BITS, offset); 95372dba584STejun Heo if (t == IDA_BITMAP_BITS) { 95472dba584STejun Heo /* no empty slot after offset, continue to the next chunk */ 95572dba584STejun Heo idr_id++; 95672dba584STejun Heo offset = 0; 95772dba584STejun Heo goto restart; 95872dba584STejun Heo } 95972dba584STejun Heo 96072dba584STejun Heo id = idr_id * IDA_BITMAP_BITS + t; 961125c4c70SFengguang Wu if (id >= MAX_IDR_BIT) 96272dba584STejun Heo return -ENOSPC; 96372dba584STejun Heo 96472dba584STejun Heo __set_bit(t, bitmap->bitmap); 96572dba584STejun Heo if (++bitmap->nr_busy == IDA_BITMAP_BITS) 96672dba584STejun Heo idr_mark_full(pa, idr_id); 96772dba584STejun Heo 96872dba584STejun Heo *p_id = id; 96972dba584STejun Heo 97072dba584STejun Heo /* Each leaf node can handle nearly a thousand slots and the 97172dba584STejun Heo * whole idea of ida is to have small memory foot print. 97272dba584STejun Heo * Throw away extra resources one by one after each successful 97372dba584STejun Heo * allocation. 97472dba584STejun Heo */ 97572dba584STejun Heo if (ida->idr.id_free_cnt || ida->free_bitmap) { 9764ae53789SNadia Derbey struct idr_layer *p = get_from_free_list(&ida->idr); 97772dba584STejun Heo if (p) 97872dba584STejun Heo kmem_cache_free(idr_layer_cache, p); 97972dba584STejun Heo } 98072dba584STejun Heo 98172dba584STejun Heo return 0; 98272dba584STejun Heo } 98372dba584STejun Heo EXPORT_SYMBOL(ida_get_new_above); 98472dba584STejun Heo 98572dba584STejun Heo /** 98672dba584STejun Heo * ida_remove - remove the given ID 98772dba584STejun Heo * @ida: ida handle 98872dba584STejun Heo * @id: ID to free 98972dba584STejun Heo */ 99072dba584STejun Heo void ida_remove(struct ida *ida, int id) 99172dba584STejun Heo { 99272dba584STejun Heo struct idr_layer *p = ida->idr.top; 99372dba584STejun Heo int shift = (ida->idr.layers - 1) * IDR_BITS; 99472dba584STejun Heo int idr_id = id / IDA_BITMAP_BITS; 99572dba584STejun Heo int offset = id % IDA_BITMAP_BITS; 99672dba584STejun Heo int n; 99772dba584STejun Heo struct ida_bitmap *bitmap; 99872dba584STejun Heo 99972dba584STejun Heo /* clear full bits while looking up the leaf idr_layer */ 100072dba584STejun Heo while ((shift > 0) && p) { 100172dba584STejun Heo n = (idr_id >> shift) & IDR_MASK; 10021d9b2e1eSTejun Heo __clear_bit(n, p->bitmap); 100372dba584STejun Heo p = p->ary[n]; 100472dba584STejun Heo shift -= IDR_BITS; 100572dba584STejun Heo } 100672dba584STejun Heo 100772dba584STejun Heo if (p == NULL) 100872dba584STejun Heo goto err; 100972dba584STejun Heo 101072dba584STejun Heo n = idr_id & IDR_MASK; 10111d9b2e1eSTejun Heo __clear_bit(n, p->bitmap); 101272dba584STejun Heo 101372dba584STejun Heo bitmap = (void *)p->ary[n]; 101472dba584STejun Heo if (!test_bit(offset, bitmap->bitmap)) 101572dba584STejun Heo goto err; 101672dba584STejun Heo 101772dba584STejun Heo /* update bitmap and remove it if empty */ 101872dba584STejun Heo __clear_bit(offset, bitmap->bitmap); 101972dba584STejun Heo if (--bitmap->nr_busy == 0) { 10201d9b2e1eSTejun Heo __set_bit(n, p->bitmap); /* to please idr_remove() */ 102172dba584STejun Heo idr_remove(&ida->idr, idr_id); 102272dba584STejun Heo free_bitmap(ida, bitmap); 102372dba584STejun Heo } 102472dba584STejun Heo 102572dba584STejun Heo return; 102672dba584STejun Heo 102772dba584STejun Heo err: 102872dba584STejun Heo printk(KERN_WARNING 102972dba584STejun Heo "ida_remove called for id=%d which is not allocated.\n", id); 103072dba584STejun Heo } 103172dba584STejun Heo EXPORT_SYMBOL(ida_remove); 103272dba584STejun Heo 103372dba584STejun Heo /** 103472dba584STejun Heo * ida_destroy - release all cached layers within an ida tree 1035ea24ea85SNaohiro Aota * @ida: ida handle 103672dba584STejun Heo */ 103772dba584STejun Heo void ida_destroy(struct ida *ida) 103872dba584STejun Heo { 103972dba584STejun Heo idr_destroy(&ida->idr); 104072dba584STejun Heo kfree(ida->free_bitmap); 104172dba584STejun Heo } 104272dba584STejun Heo EXPORT_SYMBOL(ida_destroy); 104372dba584STejun Heo 104472dba584STejun Heo /** 104588eca020SRusty Russell * ida_simple_get - get a new id. 104688eca020SRusty Russell * @ida: the (initialized) ida. 104788eca020SRusty Russell * @start: the minimum id (inclusive, < 0x8000000) 104888eca020SRusty Russell * @end: the maximum id (exclusive, < 0x8000000 or 0) 104988eca020SRusty Russell * @gfp_mask: memory allocation flags 105088eca020SRusty Russell * 105188eca020SRusty Russell * Allocates an id in the range start <= id < end, or returns -ENOSPC. 105288eca020SRusty Russell * On memory allocation failure, returns -ENOMEM. 105388eca020SRusty Russell * 105488eca020SRusty Russell * Use ida_simple_remove() to get rid of an id. 105588eca020SRusty Russell */ 105688eca020SRusty Russell int ida_simple_get(struct ida *ida, unsigned int start, unsigned int end, 105788eca020SRusty Russell gfp_t gfp_mask) 105888eca020SRusty Russell { 105988eca020SRusty Russell int ret, id; 106088eca020SRusty Russell unsigned int max; 106146cbc1d3STejun Heo unsigned long flags; 106288eca020SRusty Russell 106388eca020SRusty Russell BUG_ON((int)start < 0); 106488eca020SRusty Russell BUG_ON((int)end < 0); 106588eca020SRusty Russell 106688eca020SRusty Russell if (end == 0) 106788eca020SRusty Russell max = 0x80000000; 106888eca020SRusty Russell else { 106988eca020SRusty Russell BUG_ON(end < start); 107088eca020SRusty Russell max = end - 1; 107188eca020SRusty Russell } 107288eca020SRusty Russell 107388eca020SRusty Russell again: 107488eca020SRusty Russell if (!ida_pre_get(ida, gfp_mask)) 107588eca020SRusty Russell return -ENOMEM; 107688eca020SRusty Russell 107746cbc1d3STejun Heo spin_lock_irqsave(&simple_ida_lock, flags); 107888eca020SRusty Russell ret = ida_get_new_above(ida, start, &id); 107988eca020SRusty Russell if (!ret) { 108088eca020SRusty Russell if (id > max) { 108188eca020SRusty Russell ida_remove(ida, id); 108288eca020SRusty Russell ret = -ENOSPC; 108388eca020SRusty Russell } else { 108488eca020SRusty Russell ret = id; 108588eca020SRusty Russell } 108688eca020SRusty Russell } 108746cbc1d3STejun Heo spin_unlock_irqrestore(&simple_ida_lock, flags); 108888eca020SRusty Russell 108988eca020SRusty Russell if (unlikely(ret == -EAGAIN)) 109088eca020SRusty Russell goto again; 109188eca020SRusty Russell 109288eca020SRusty Russell return ret; 109388eca020SRusty Russell } 109488eca020SRusty Russell EXPORT_SYMBOL(ida_simple_get); 109588eca020SRusty Russell 109688eca020SRusty Russell /** 109788eca020SRusty Russell * ida_simple_remove - remove an allocated id. 109888eca020SRusty Russell * @ida: the (initialized) ida. 109988eca020SRusty Russell * @id: the id returned by ida_simple_get. 110088eca020SRusty Russell */ 110188eca020SRusty Russell void ida_simple_remove(struct ida *ida, unsigned int id) 110288eca020SRusty Russell { 110346cbc1d3STejun Heo unsigned long flags; 110446cbc1d3STejun Heo 110588eca020SRusty Russell BUG_ON((int)id < 0); 110646cbc1d3STejun Heo spin_lock_irqsave(&simple_ida_lock, flags); 110788eca020SRusty Russell ida_remove(ida, id); 110846cbc1d3STejun Heo spin_unlock_irqrestore(&simple_ida_lock, flags); 110988eca020SRusty Russell } 111088eca020SRusty Russell EXPORT_SYMBOL(ida_simple_remove); 111188eca020SRusty Russell 111288eca020SRusty Russell /** 111372dba584STejun Heo * ida_init - initialize ida handle 111472dba584STejun Heo * @ida: ida handle 111572dba584STejun Heo * 111672dba584STejun Heo * This function is use to set up the handle (@ida) that you will pass 111772dba584STejun Heo * to the rest of the functions. 111872dba584STejun Heo */ 111972dba584STejun Heo void ida_init(struct ida *ida) 112072dba584STejun Heo { 112172dba584STejun Heo memset(ida, 0, sizeof(struct ida)); 112272dba584STejun Heo idr_init(&ida->idr); 112372dba584STejun Heo 112472dba584STejun Heo } 112572dba584STejun Heo EXPORT_SYMBOL(ida_init); 1126