/* * 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) idrLines 1–500 of 1161. Load more
/* * 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