diff options
Diffstat (limited to 'lib/idr.c')
| -rw-r--r-- | lib/idr.c | 644 |
1 files changed, 424 insertions, 220 deletions
diff --git a/lib/idr.c b/lib/idr.c index e15502e8b21..39158abebad 100644 --- a/lib/idr.c +++ b/lib/idr.c @@ -18,24 +18,51 @@ * pointer or what ever, we treat it as a (void *). You can pass this * id to a user for him to pass back at a later time. You then pass * that id to this code and it returns your pointer. - - * You can release ids at any time. When all ids are released, most of - * the memory is returned (we keep IDR_FREE_MAX) in a local pool so we - * don't need to go to the memory "store" during an id allocate, just - * so you don't need to be too concerned about locking and conflicts - * with the slab allocator. */ #ifndef TEST // to test in user space... #include <linux/slab.h> #include <linux/init.h> -#include <linux/module.h> +#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) { @@ -52,6 +79,62 @@ static struct idr_layer *get_from_free_list(struct idr *idp) 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; @@ -60,8 +143,10 @@ static void idr_layer_rcu_free(struct rcu_head *head) kmem_cache_free(idr_layer_cache, layer); } -static inline void free_layer(struct idr_layer *p) +static inline void free_layer(struct idr *idr, struct idr_layer *p) { + if (idr->hint == p) + RCU_INIT_POINTER(idr->hint, NULL); call_rcu(&p->rcu_head, idr_layer_rcu_free); } @@ -90,37 +175,24 @@ 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); + __set_bit(id & IDR_MASK, p->bitmap); /* * If this layer is full mark the bit in the layer above to * show that this part of the radix tree is full. This may * complete the layer above and require walking up the radix * tree. */ - while (p->bitmap == IDR_FULL) { + while (bitmap_full(p->bitmap, IDR_SIZE)) { if (!(p = pa[++l])) break; id = id >> IDR_BITS; - __set_bit((id & IDR_MASK), &p->bitmap); + __set_bit((id & IDR_MASK), p->bitmap); } } -/** - * idr_pre_get - reserve resources for idr allocation - * @idp: idr handle - * @gfp_mask: memory allocation flags - * - * This function should be called prior to calling the idr_get_new* functions. - * It preallocates enough memory to satisfy the worst possible allocation. The - * caller should pass in GFP_KERNEL if possible. This of course requires that - * no spinning locks be held. - * - * If the system is REALLY out of memory this function returns %0, - * otherwise %1. - */ -int idr_pre_get(struct idr *idp, gfp_t gfp_mask) +static int __idr_pre_get(struct idr *idp, gfp_t gfp_mask) { - while (idp->id_free_cnt < IDR_FREE_MAX) { + while (idp->id_free_cnt < MAX_IDR_FREE) { struct idr_layer *new; new = kmem_cache_zalloc(idr_layer_cache, gfp_mask); if (new == NULL) @@ -129,14 +201,29 @@ int idr_pre_get(struct idr *idp, gfp_t gfp_mask) } return 1; } -EXPORT_SYMBOL(idr_pre_get); -static int sub_alloc(struct idr *idp, int *starting_id, struct idr_layer **pa) +/** + * 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; - unsigned long bm; id = *starting_id; restart: @@ -148,8 +235,7 @@ static int sub_alloc(struct idr *idp, int *starting_id, struct idr_layer **pa) * We run around this while until we reach the leaf node... */ n = (id >> (IDR_BITS*l)) & IDR_MASK; - bm = ~p->bitmap; - m = find_next_bit(&bm, IDR_SIZE, n); + m = find_next_zero_bit(p->bitmap, IDR_SIZE, n); if (m == IDR_SIZE) { /* no space available go back to previous layer. */ l++; @@ -157,9 +243,9 @@ static int sub_alloc(struct idr *idp, int *starting_id, struct idr_layer **pa) 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)) { + if (id > idr_max(idp->layers)) { *starting_id = id; - return IDR_NEED_TO_GROW; + return -EAGAIN; } p = pa[l]; BUG_ON(!p); @@ -177,18 +263,19 @@ static int sub_alloc(struct idr *idp, int *starting_id, struct idr_layer **pa) sh = IDR_BITS*l; id = ((id >> sh) ^ n ^ m) << sh; } - if ((id >= MAX_ID_BIT) || (id < 0)) - return IDR_NOMORE_SPACE; + 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 = get_from_free_list(idp); + new = idr_layer_alloc(gfp_mask, layer_idr); if (!new) - return -1; + return -ENOMEM; new->layer = l-1; + new->prefix = id & idr_layer_prefix_mask(new->layer); rcu_assign_pointer(p->ary[m], new); p->count++; } @@ -201,7 +288,8 @@ static int sub_alloc(struct idr *idp, int *starting_id, struct idr_layer **pa) } static int idr_get_empty_slot(struct idr *idp, int starting_id, - struct idr_layer **pa) + struct idr_layer **pa, gfp_t gfp_mask, + struct idr *layer_idr) { struct idr_layer *p, *new; int layers, v, id; @@ -212,8 +300,8 @@ build_up: p = idp->top; layers = idp->layers; if (unlikely(!p)) { - if (!(p = get_from_free_list(idp))) - return -1; + if (!(p = idr_layer_alloc(gfp_mask, layer_idr))) + return -ENOMEM; p->layer = 0; layers = 1; } @@ -221,7 +309,7 @@ build_up: * Add a new layer to the top of the tree if the requested * id is larger than the currently allocated space. */ - while ((layers < (MAX_LEVEL - 1)) && (id >= (1 << (layers*IDR_BITS)))) { + while (id > idr_max(layers)) { layers++; if (!p->count) { /* special case: if the tree is currently empty, @@ -229,9 +317,10 @@ build_up: * upwards. */ p->layer++; + WARN_ON_ONCE(p->prefix); continue; } - if (!(new = get_from_free_list(idp))) { + if (!(new = idr_layer_alloc(gfp_mask, layer_idr))) { /* * The allocation failed. If we built part of * the structure tear it down. @@ -240,122 +329,187 @@ build_up: for (new = p; p && p != idp->top; new = p) { p = p->ary[0]; new->ary[0] = NULL; - new->bitmap = new->count = 0; + new->count = 0; + bitmap_clear(new->bitmap, 0, IDR_SIZE); __move_to_free_list(idp, new); } spin_unlock_irqrestore(&idp->lock, flags); - return -1; + return -ENOMEM; } new->ary[0] = p; new->count = 1; new->layer = layers-1; - if (p->bitmap == IDR_FULL) - __set_bit(0, &new->bitmap); + 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); - if (v == IDR_NEED_TO_GROW) + v = sub_alloc(idp, &id, pa, gfp_mask, layer_idr); + if (v == -EAGAIN) goto build_up; return(v); } -static int idr_get_new_above_int(struct idr *idp, void *ptr, int starting_id) +/* + * @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) { - struct idr_layer *pa[MAX_LEVEL]; - int id; + /* update hint used for lookup, cleared from free_layer() */ + rcu_assign_pointer(idr->hint, pa[0]); - id = idr_get_empty_slot(idp, starting_id, pa); - if (id >= 0) { - /* - * Successfully found an empty slot. Install the user - * pointer and mark the slot full. - */ - rcu_assign_pointer(pa[0]->ary[id & IDR_MASK], - (struct idr_layer *)ptr); - pa[0]->count++; - idr_mark_full(pa, id); - } - - return id; + rcu_assign_pointer(pa[0]->ary[id & IDR_MASK], (struct idr_layer *)ptr); + pa[0]->count++; + idr_mark_full(pa, id); } + /** - * idr_get_new_above - allocate new idr entry above or equal to a start id - * @idp: idr handle - * @ptr: pointer you want associated with the id - * @starting_id: id to start search at - * @id: pointer to the allocated handle + * 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. * - * This is the allocate id function. It should be called with any - * required locks. + * 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. * - * If allocation from IDR's private freelist fails, idr_get_new_above() will - * return %-EAGAIN. The caller should retry the idr_pre_get() call to refill - * IDR's preallocation and then retry the idr_get_new_above() call. + * 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. * - * If the idr is full idr_get_new_above() will return %-ENOSPC. + * idr_preload(GFP_KERNEL); + * spin_lock(lock); * - * @id returns a value in the range @starting_id ... %0x7fffffff + * id = idr_alloc(idr, ptr, start, end, GFP_NOWAIT); + * + * spin_unlock(lock); + * idr_preload_end(); + * if (id < 0) + * error; */ -int idr_get_new_above(struct idr *idp, void *ptr, int starting_id, int *id) +void idr_preload(gfp_t gfp_mask) { - int rv; + /* + * 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(); - rv = idr_get_new_above_int(idp, ptr, starting_id); /* - * This is a cheap hack until the IDR code can be fixed to - * return proper error values. + * 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. */ - if (rv < 0) - return _idr_rc_to_errno(rv); - *id = rv; - return 0; + 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_get_new_above); +EXPORT_SYMBOL(idr_preload); /** - * idr_get_new - allocate new idr entry - * @idp: idr handle - * @ptr: pointer you want associated with the id - * @id: pointer to the allocated handle + * 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 * - * If allocation from IDR's private freelist fails, idr_get_new_above() will - * return %-EAGAIN. The caller should retry the idr_pre_get() call to refill - * IDR's preallocation and then retry the idr_get_new_above() call. + * 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. * - * If the idr is full idr_get_new_above() will return %-ENOSPC. + * 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. * - * @id returns a value in the range %0 ... %0x7fffffff + * 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_get_new(struct idr *idp, void *ptr, int *id) +int idr_alloc(struct idr *idr, void *ptr, int start, int end, gfp_t gfp_mask) { - int rv; + int max = end > 0 ? end - 1 : INT_MAX; /* inclusive upper limit */ + struct idr_layer *pa[MAX_IDR_LEVEL + 1]; + int id; - rv = idr_get_new_above_int(idp, ptr, 0); - /* - * This is a cheap hack until the IDR code can be fixed to - * return proper error values. - */ - if (rv < 0) - return _idr_rc_to_errno(rv); - *id = rv; - return 0; + might_sleep_if(gfp_mask & __GFP_WAIT); + + /* sanity checks */ + if (WARN_ON_ONCE(start < 0)) + return -EINVAL; + if (unlikely(max < start)) + return -ENOSPC; + + /* allocate id */ + id = idr_get_empty_slot(idr, start, pa, gfp_mask, NULL); + if (unlikely(id < 0)) + return id; + if (unlikely(id > max)) + return -ENOSPC; + + idr_fill_slot(idr, ptr, id, pa); + return id; +} +EXPORT_SYMBOL_GPL(idr_alloc); + +/** + * idr_alloc_cyclic - allocate new idr entry in a cyclical fashion + * @idr: the (initialized) idr + * @ptr: pointer to be associated with the new id + * @start: the minimum id (inclusive) + * @end: the maximum id (exclusive, <= 0 for max) + * @gfp_mask: memory allocation flags + * + * Essentially the same as idr_alloc, but prefers to allocate progressively + * higher ids if it can. If the "cur" counter wraps, then it will start again + * at the "start" end of the range and allocate one that has already been used. + */ +int idr_alloc_cyclic(struct idr *idr, void *ptr, int start, int end, + gfp_t gfp_mask) +{ + int id; + + id = idr_alloc(idr, ptr, max(start, idr->cur), end, gfp_mask); + if (id == -ENOSPC) + id = idr_alloc(idr, ptr, start, end, gfp_mask); + + if (likely(id >= 0)) + idr->cur = id + 1; + return id; } -EXPORT_SYMBOL(idr_get_new); +EXPORT_SYMBOL(idr_alloc_cyclic); static void idr_remove_warning(int id) { - printk(KERN_WARNING - "idr_remove called for id=%d which is not allocated.\n", id); - dump_stack(); + WARN(1, "idr_remove called for id=%d which is not allocated.\n", id); } static void sub_remove(struct idr *idp, int shift, int id) { struct idr_layer *p = idp->top; - struct idr_layer **pa[MAX_LEVEL]; + struct idr_layer **pa[MAX_IDR_LEVEL + 1]; struct idr_layer ***paa = &pa[0]; struct idr_layer *to_free; int n; @@ -365,26 +519,26 @@ static void sub_remove(struct idr *idp, int shift, int id) while ((shift > 0) && p) { n = (id >> shift) & IDR_MASK; - __clear_bit(n, &p->bitmap); + __clear_bit(n, p->bitmap); *++paa = &p->ary[n]; p = p->ary[n]; shift -= IDR_BITS; } n = id & IDR_MASK; - if (likely(p != NULL && test_bit(n, &p->bitmap))){ - __clear_bit(n, &p->bitmap); - rcu_assign_pointer(p->ary[n], NULL); + if (likely(p != NULL && test_bit(n, p->bitmap))) { + __clear_bit(n, p->bitmap); + RCU_INIT_POINTER(p->ary[n], NULL); to_free = NULL; while(*paa && ! --((**paa)->count)){ if (to_free) - free_layer(to_free); + free_layer(idp, to_free); to_free = **paa; **paa-- = NULL; } if (!*paa) idp->layers = 0; if (to_free) - free_layer(to_free); + free_layer(idp, to_free); } else idr_remove_warning(id); } @@ -399,8 +553,13 @@ void idr_remove(struct idr *idp, int id) struct idr_layer *p; struct idr_layer *to_free; - /* Mask off upper bits we don't use for the search. */ - id &= MAX_ID_MASK; + if (id < 0) + return; + + if (id > idr_max(idp->layers)) { + idr_remove_warning(id); + return; + } sub_remove(idp, (idp->layers - 1) * IDR_BITS, id); if (idp->top && idp->top->count == 1 && (idp->layers > 1) && @@ -415,50 +574,28 @@ void idr_remove(struct idr *idp, int id) p = idp->top->ary[0]; rcu_assign_pointer(idp->top, p); --idp->layers; - to_free->bitmap = to_free->count = 0; - free_layer(to_free); + to_free->count = 0; + bitmap_clear(to_free->bitmap, 0, IDR_SIZE); + free_layer(idp, to_free); } - while (idp->id_free_cnt >= IDR_FREE_MAX) { - p = get_from_free_list(idp); - /* - * Note: we don't call the rcu callback here, since the only - * layers that fall into the freelist are those that have been - * preallocated. - */ - kmem_cache_free(idr_layer_cache, p); - } - return; } EXPORT_SYMBOL(idr_remove); -/** - * idr_remove_all - remove all ids from the given idr tree - * @idp: idr handle - * - * idr_destroy() only frees up unused, cached idp_layers, but this - * function will remove all id mappings and leave all idp_layers - * unused. - * - * A typical clean-up sequence for objects stored in an idr tree will - * use idr_for_each() to free all objects, if necessay, then - * idr_remove_all() to remove all ids, and idr_destroy() to free - * up the cached idr_layers. - */ -void idr_remove_all(struct idr *idp) +static void __idr_remove_all(struct idr *idp) { int n, id, max; int bt_mask; struct idr_layer *p; - struct idr_layer *pa[MAX_LEVEL]; + struct idr_layer *pa[MAX_IDR_LEVEL + 1]; struct idr_layer **paa = &pa[0]; n = idp->layers * IDR_BITS; p = idp->top; - rcu_assign_pointer(idp->top, NULL); - max = 1 << n; + RCU_INIT_POINTER(idp->top, NULL); + max = idr_max(idp->layers); id = 0; - while (id < max) { + while (id >= 0 && id <= max) { while (n > IDR_BITS && p) { n -= IDR_BITS; *paa++ = p; @@ -470,21 +607,31 @@ void idr_remove_all(struct idr *idp) /* Get the highest bit that the above add changed from 0->1. */ while (n < fls(id ^ bt_mask)) { if (p) - free_layer(p); + free_layer(idp, p); n += IDR_BITS; p = *--paa; } } idp->layers = 0; } -EXPORT_SYMBOL(idr_remove_all); /** * idr_destroy - release all cached layers within an idr tree * @idp: idr handle + * + * Free all id mappings and all idp_layers. After this function, @idp is + * completely unused and can be freed / recycled. The caller is + * responsible for ensuring that no one else accesses @idp during or after + * idr_destroy(). + * + * A typical clean-up sequence for objects stored in an idr tree will use + * idr_for_each() to free all objects, if necessay, then idr_destroy() to + * free up the id mappings and cached idr_layers. */ void idr_destroy(struct idr *idp) { + __idr_remove_all(idp); + while (idp->id_free_cnt) { struct idr_layer *p = get_from_free_list(idp); kmem_cache_free(idr_layer_cache, p); @@ -492,32 +639,20 @@ void idr_destroy(struct idr *idp) } EXPORT_SYMBOL(idr_destroy); -/** - * idr_find - return pointer for given id - * @idp: idr handle - * @id: lookup key - * - * Return the pointer given the id it has been registered with. A %NULL - * return indicates that @id is not valid or you passed %NULL in - * idr_get_new(). - * - * This function can be called under rcu_read_lock(), given that the leaf - * pointers lifetimes are correctly managed. - */ -void *idr_find(struct idr *idp, int id) +void *idr_find_slowpath(struct idr *idp, int id) { int n; struct idr_layer *p; + if (id < 0) + return NULL; + p = rcu_dereference_raw(idp->top); if (!p) return NULL; n = (p->layer+1) * IDR_BITS; - /* Mask off upper bits we don't use for the search. */ - id &= MAX_ID_MASK; - - if (id >= (1 << n)) + if (id > idr_max(p->layer + 1)) return NULL; BUG_ON(n == 0); @@ -528,7 +663,7 @@ void *idr_find(struct idr *idp, int id) } return((void *)p); } -EXPORT_SYMBOL(idr_find); +EXPORT_SYMBOL(idr_find_slowpath); /** * idr_for_each - iterate through all stored pointers @@ -553,15 +688,15 @@ int idr_for_each(struct idr *idp, { int n, id, max, error = 0; struct idr_layer *p; - struct idr_layer *pa[MAX_LEVEL]; + struct idr_layer *pa[MAX_IDR_LEVEL + 1]; struct idr_layer **paa = &pa[0]; n = idp->layers * IDR_BITS; p = rcu_dereference_raw(idp->top); - max = 1 << n; + max = idr_max(idp->layers); id = 0; - while (id < max) { + while (id >= 0 && id <= max) { while (n > 0 && p) { n -= IDR_BITS; *paa++ = p; @@ -593,23 +728,25 @@ EXPORT_SYMBOL(idr_for_each); * Returns pointer to registered object with id, which is next number to * given id. After being looked up, *@nextidp will be updated for the next * iteration. + * + * This function can be called under rcu_read_lock(), given that the leaf + * pointers lifetimes are correctly managed. */ - void *idr_get_next(struct idr *idp, int *nextidp) { - struct idr_layer *p, *pa[MAX_LEVEL]; + struct idr_layer *p, *pa[MAX_IDR_LEVEL + 1]; struct idr_layer **paa = &pa[0]; int id = *nextidp; int n, max; /* find first ent */ - n = idp->layers * IDR_BITS; - max = 1 << n; p = rcu_dereference_raw(idp->top); if (!p) return NULL; + n = (p->layer + 1) * IDR_BITS; + max = idr_max(p->layer + 1); - while (id < max) { + while (id >= 0 && id <= max) { while (n > 0 && p) { n -= IDR_BITS; *paa++ = p; @@ -621,7 +758,14 @@ void *idr_get_next(struct idr *idp, int *nextidp) return p; } - id += 1 << n; + /* + * Proceed to the next layer at the current level. Unlike + * idr_for_each(), @id isn't guaranteed to be aligned to + * layer boundary at this point and adding 1 << n may + * incorrectly skip IDs. Make sure we jump to the + * beginning of the next layer using round_up(). + */ + id = round_up(id + 1, 1 << n); while (n < fls(id)) { n += IDR_BITS; p = *--paa; @@ -649,25 +793,24 @@ void *idr_replace(struct idr *idp, void *ptr, int id) int n; struct idr_layer *p, *old_p; - p = idp->top; - if (!p) + if (id < 0) return ERR_PTR(-EINVAL); - n = (p->layer+1) * IDR_BITS; - - id &= MAX_ID_MASK; + p = idp->top; + if (!p) + return ERR_PTR(-ENOENT); - if (id >= (1 << n)) - return ERR_PTR(-EINVAL); + if (id > idr_max(p->layer + 1)) + return ERR_PTR(-ENOENT); - n -= IDR_BITS; + n = p->layer * IDR_BITS; while ((n > 0) && p) { p = p->ary[(id >> n) & IDR_MASK]; n -= IDR_BITS; } n = id & IDR_MASK; - if (unlikely(p == NULL || !test_bit(n, &p->bitmap))) + if (unlikely(p == NULL || !test_bit(n, p->bitmap))) return ERR_PTR(-ENOENT); old_p = p->ary[n]; @@ -697,6 +840,16 @@ void idr_init(struct idr *idp) } EXPORT_SYMBOL(idr_init); +static int idr_has_entry(int id, void *p, void *data) +{ + return 1; +} + +bool idr_is_empty(struct idr *idp) +{ + return !idr_for_each(idp, idr_has_entry, NULL); +} +EXPORT_SYMBOL(idr_is_empty); /** * DOC: IDA description @@ -741,7 +894,7 @@ static void free_bitmap(struct ida *ida, struct ida_bitmap *bitmap) int ida_pre_get(struct ida *ida, gfp_t gfp_mask) { /* allocate idr_layers */ - if (!idr_pre_get(&ida->idr, gfp_mask)) + if (!__idr_pre_get(&ida->idr, gfp_mask)) return 0; /* allocate free_bitmap */ @@ -765,8 +918,8 @@ EXPORT_SYMBOL(ida_pre_get); * @starting_id: id to start search at * @p_id: pointer to the allocated handle * - * Allocate new ID above or equal to @ida. It should be called with - * any required locks. + * Allocate new ID above or equal to @starting_id. It should be called + * with any required locks. * * If memory is required, it will return %-EAGAIN, you should unlock * and go back to the ida_pre_get() call. If the ida is full, it will @@ -776,7 +929,7 @@ EXPORT_SYMBOL(ida_pre_get); */ int ida_get_new_above(struct ida *ida, int starting_id, int *p_id) { - struct idr_layer *pa[MAX_LEVEL]; + struct idr_layer *pa[MAX_IDR_LEVEL + 1]; struct ida_bitmap *bitmap; unsigned long flags; int idr_id = starting_id / IDA_BITMAP_BITS; @@ -785,11 +938,11 @@ int ida_get_new_above(struct ida *ida, int starting_id, int *p_id) restart: /* get vacant slot */ - t = idr_get_empty_slot(&ida->idr, idr_id, pa); + t = idr_get_empty_slot(&ida->idr, idr_id, pa, 0, &ida->idr); if (t < 0) - return _idr_rc_to_errno(t); + return t == -ENOMEM ? -EAGAIN : t; - if (t * IDA_BITMAP_BITS >= MAX_ID_BIT) + if (t * IDA_BITMAP_BITS >= MAX_IDR_BIT) return -ENOSPC; if (t != idr_id) @@ -823,7 +976,7 @@ int ida_get_new_above(struct ida *ida, int starting_id, int *p_id) } id = idr_id * IDA_BITMAP_BITS + t; - if (id >= MAX_ID_BIT) + if (id >= MAX_IDR_BIT) return -ENOSPC; __set_bit(t, bitmap->bitmap); @@ -848,25 +1001,6 @@ int ida_get_new_above(struct ida *ida, int starting_id, int *p_id) EXPORT_SYMBOL(ida_get_new_above); /** - * ida_get_new - allocate new ID - * @ida: idr handle - * @p_id: pointer to the allocated handle - * - * Allocate new ID. It should be called with any required locks. - * - * If memory is required, it will return %-EAGAIN, you should unlock - * and go back to the idr_pre_get() call. If the idr is full, it will - * return %-ENOSPC. - * - * @id returns a value in the range %0 ... %0x7fffffff. - */ -int ida_get_new(struct ida *ida, int *p_id) -{ - return ida_get_new_above(ida, 0, p_id); -} -EXPORT_SYMBOL(ida_get_new); - -/** * ida_remove - remove the given ID * @ida: ida handle * @id: ID to free @@ -880,10 +1014,13 @@ void ida_remove(struct ida *ida, int id) int n; struct ida_bitmap *bitmap; + if (idr_id > idr_max(ida->idr.layers)) + goto err; + /* clear full bits while looking up the leaf idr_layer */ while ((shift > 0) && p) { n = (idr_id >> shift) & IDR_MASK; - __clear_bit(n, &p->bitmap); + __clear_bit(n, p->bitmap); p = p->ary[n]; shift -= IDR_BITS; } @@ -892,16 +1029,16 @@ void ida_remove(struct ida *ida, int id) goto err; n = idr_id & IDR_MASK; - __clear_bit(n, &p->bitmap); + __clear_bit(n, p->bitmap); bitmap = (void *)p->ary[n]; - if (!test_bit(offset, bitmap->bitmap)) + if (!bitmap || !test_bit(offset, bitmap->bitmap)) goto err; /* update bitmap and remove it if empty */ __clear_bit(offset, bitmap->bitmap); if (--bitmap->nr_busy == 0) { - __set_bit(n, &p->bitmap); /* to please idr_remove() */ + __set_bit(n, p->bitmap); /* to please idr_remove() */ idr_remove(&ida->idr, idr_id); free_bitmap(ida, bitmap); } @@ -909,8 +1046,7 @@ void ida_remove(struct ida *ida, int id) return; err: - printk(KERN_WARNING - "ida_remove called for id=%d which is not allocated.\n", id); + WARN(1, "ida_remove called for id=%d which is not allocated.\n", id); } EXPORT_SYMBOL(ida_remove); @@ -926,6 +1062,74 @@ void ida_destroy(struct ida *ida) EXPORT_SYMBOL(ida_destroy); /** + * ida_simple_get - get a new id. + * @ida: the (initialized) ida. + * @start: the minimum id (inclusive, < 0x8000000) + * @end: the maximum id (exclusive, < 0x8000000 or 0) + * @gfp_mask: memory allocation flags + * + * Allocates an id in the range start <= id < end, or returns -ENOSPC. + * On memory allocation failure, returns -ENOMEM. + * + * Use ida_simple_remove() to get rid of an id. + */ +int ida_simple_get(struct ida *ida, unsigned int start, unsigned int end, + gfp_t gfp_mask) +{ + int ret, id; + unsigned int max; + unsigned long flags; + + BUG_ON((int)start < 0); + BUG_ON((int)end < 0); + + if (end == 0) + max = 0x80000000; + else { + BUG_ON(end < start); + max = end - 1; + } + +again: + if (!ida_pre_get(ida, gfp_mask)) + return -ENOMEM; + + spin_lock_irqsave(&simple_ida_lock, flags); + ret = ida_get_new_above(ida, start, &id); + if (!ret) { + if (id > max) { + ida_remove(ida, id); + ret = -ENOSPC; + } else { + ret = id; + } + } + spin_unlock_irqrestore(&simple_ida_lock, flags); + + if (unlikely(ret == -EAGAIN)) + goto again; + + return ret; +} +EXPORT_SYMBOL(ida_simple_get); + +/** + * ida_simple_remove - remove an allocated id. + * @ida: the (initialized) ida. + * @id: the id returned by ida_simple_get. + */ +void ida_simple_remove(struct ida *ida, unsigned int id) +{ + unsigned long flags; + + BUG_ON((int)id < 0); + spin_lock_irqsave(&simple_ida_lock, flags); + ida_remove(ida, id); + spin_unlock_irqrestore(&simple_ida_lock, flags); +} +EXPORT_SYMBOL(ida_simple_remove); + +/** * ida_init - initialize ida handle * @ida: ida handle * |