-/*
- * 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.
- */
-
-#ifndef TEST // to test in user space...
-#include <linux/slab.h>
-#include <linux/init.h>
+#include <linux/bitmap.h>
#include <linux/export.h>
-#endif
-#include <linux/err.h>
-#include <linux/string.h>
#include <linux/idr.h>
+#include <linux/slab.h>
#include <linux/spinlock.h>
-#include <linux/percpu.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);
+DEFINE_PER_CPU(struct ida_bitmap *, ida_bitmap);
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 == 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);
- }
-}
-
-static 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;
-}
-
-/**
- * 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 > idr_max(idp->layers)) {
- *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);
-}
-
-
-/**
- * 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(gfpflags_allow_blocking(gfp_mask));
-
- 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
+ * idr_alloc - allocate an id
+ * @idr: idr handle
* @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
+ * @end: the maximum id (exclusive)
+ * @gfp: 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.
+ * Allocates an unused ID in the range [start, end). Returns -ENOSPC
+ * if there are no unused IDs in that range.
*
* 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.
+ * Simultaneous modifications to the @idr are not allowed and should be
+ * prevented by the user, usually with a lock. idr_alloc() may be called
+ * concurrently with read-only accesses to the @idr, such as idr_find() and
+ * idr_for_each_entry().
*/
-int idr_alloc(struct idr *idr, void *ptr, int start, int end, gfp_t gfp_mask)
+int idr_alloc(struct idr *idr, void *ptr, int start, int end, gfp_t gfp)
{
- int max = end > 0 ? end - 1 : INT_MAX; /* inclusive upper limit */
- struct idr_layer *pa[MAX_IDR_LEVEL + 1];
- int id;
+ void __rcu **slot;
+ struct radix_tree_iter iter;
- might_sleep_if(gfpflags_allow_blocking(gfp_mask));
-
- /* sanity checks */
if (WARN_ON_ONCE(start < 0))
return -EINVAL;
- if (unlikely(max < start))
- return -ENOSPC;
+ if (WARN_ON_ONCE(radix_tree_is_internal_node(ptr)))
+ return -EINVAL;
- /* 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;
+ radix_tree_iter_init(&iter, start);
+ slot = idr_get_free(&idr->idr_rt, &iter, gfp, end);
+ if (IS_ERR(slot))
+ return PTR_ERR(slot);
- idr_fill_slot(idr, ptr, id, pa);
- return id;
+ radix_tree_iter_replace(&idr->idr_rt, &iter, slot, ptr);
+ radix_tree_iter_tag_clear(&idr->idr_rt, &iter, IDR_FREE);
+ return iter.index;
}
EXPORT_SYMBOL_GPL(idr_alloc);
/**
* idr_alloc_cyclic - allocate new idr entry in a cyclical fashion
- * @idr: the (initialized) idr
+ * @idr: idr handle
* @ptr: pointer to be associated with the new id
* @start: the minimum id (inclusive)
- * @end: the maximum id (exclusive, <= 0 for max)
- * @gfp_mask: memory allocation flags
- *
- * Essentially the same as idr_alloc, but prefers to allocate progressively
- * higher ids if it can. If the "cur" counter wraps, then it will start again
- * at the "start" end of the range and allocate one that has already been used.
- */
-int idr_alloc_cyclic(struct idr *idr, void *ptr, int start, int end,
- gfp_t gfp_mask)
-{
- int id;
-
- id = idr_alloc(idr, ptr, max(start, idr->cur), end, gfp_mask);
- if (id == -ENOSPC)
- id = idr_alloc(idr, ptr, start, end, gfp_mask);
-
- if (likely(id >= 0))
- idr->cur = id + 1;
- return id;
-}
-EXPORT_SYMBOL(idr_alloc_cyclic);
-
-static void idr_remove_warning(int id)
-{
- 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_IDR_LEVEL + 1];
- struct idr_layer ***paa = &pa[0];
- struct idr_layer *to_free;
- int n;
-
- *paa = NULL;
- *++paa = &idp->top;
-
- while ((shift > 0) && p) {
- n = (id >> shift) & IDR_MASK;
- __clear_bit(n, p->bitmap);
- *++paa = &p->ary[n];
- p = p->ary[n];
- shift -= IDR_BITS;
- }
- n = id & IDR_MASK;
- if (likely(p != NULL && test_bit(n, p->bitmap))) {
- __clear_bit(n, p->bitmap);
- RCU_INIT_POINTER(p->ary[n], NULL);
- to_free = NULL;
- while(*paa && ! --((**paa)->count)){
- if (to_free)
- free_layer(idp, to_free);
- to_free = **paa;
- **paa-- = NULL;
- }
- if (!*paa)
- idp->layers = 0;
- if (to_free)
- free_layer(idp, to_free);
- } else
- idr_remove_warning(id);
-}
-
-/**
- * idr_remove - remove the given id and free its slot
- * @idp: idr handle
- * @id: unique key
- */
-void idr_remove(struct idr *idp, int id)
-{
- struct idr_layer *p;
- struct idr_layer *to_free;
-
- if (id < 0)
- return;
-
- 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) &&
- idp->top->ary[0]) {
- /*
- * Single child at leftmost slot: we can shrink the tree.
- * This level is not needed anymore since when layers are
- * inserted, they are inserted at the top of the existing
- * tree.
- */
- to_free = idp->top;
- p = idp->top->ary[0];
- rcu_assign_pointer(idp->top, p);
- --idp->layers;
- to_free->count = 0;
- bitmap_clear(to_free->bitmap, 0, IDR_SIZE);
- free_layer(idp, to_free);
- }
-}
-EXPORT_SYMBOL(idr_remove);
-
-static void __idr_remove_all(struct idr *idp)
-{
- int n, id, max;
- int bt_mask;
- struct idr_layer *p;
- struct idr_layer *pa[MAX_IDR_LEVEL + 1];
- struct idr_layer **paa = &pa[0];
-
- n = idp->layers * IDR_BITS;
- *paa = idp->top;
- RCU_INIT_POINTER(idp->top, NULL);
- max = idr_max(idp->layers);
-
- id = 0;
- while (id >= 0 && id <= max) {
- p = *paa;
- while (n > IDR_BITS && p) {
- n -= IDR_BITS;
- p = p->ary[(id >> n) & IDR_MASK];
- *++paa = p;
- }
-
- bt_mask = id;
- id += 1 << n;
- /* Get the highest bit that the above add changed from 0->1. */
- while (n < fls(id ^ bt_mask)) {
- if (*paa)
- free_layer(idp, *paa);
- n += IDR_BITS;
- --paa;
- }
- }
- idp->layers = 0;
-}
-
-/**
- * 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().
+ * @end: the maximum id (exclusive)
+ * @gfp: memory allocation flags
*
- * A typical clean-up sequence for objects stored in an idr tree will use
- * idr_for_each() to free all objects, if necessary, then idr_destroy() to
- * free up the id mappings and cached idr_layers.
+ * Allocates an ID larger than the last ID allocated if one is available.
+ * If not, it will attempt to allocate the smallest ID that is larger or
+ * equal to @start.
*/
-void idr_destroy(struct idr *idp)
+int idr_alloc_cyclic(struct idr *idr, void *ptr, int start, int end, gfp_t gfp)
{
- __idr_remove_all(idp);
+ int id, curr = idr->idr_next;
- while (idp->id_free_cnt) {
- struct idr_layer *p = get_from_free_list(idp);
- kmem_cache_free(idr_layer_cache, p);
- }
-}
-EXPORT_SYMBOL(idr_destroy);
+ if (curr < start)
+ curr = start;
-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;
+ id = idr_alloc(idr, ptr, curr, end, gfp);
+ if ((id == -ENOSPC) && (curr > start))
+ id = idr_alloc(idr, ptr, start, curr, gfp);
- if (id > idr_max(p->layer + 1))
- return NULL;
- BUG_ON(n == 0);
+ if (id >= 0)
+ idr->idr_next = id + 1U;
- while (n > 0 && p) {
- n -= IDR_BITS;
- BUG_ON(n != p->layer*IDR_BITS);
- p = rcu_dereference_raw(p->ary[(id >> n) & IDR_MASK]);
- }
- return((void *)p);
+ return id;
}
-EXPORT_SYMBOL(idr_find_slowpath);
+EXPORT_SYMBOL(idr_alloc_cyclic);
/**
* idr_for_each - iterate through all stored pointers
- * @idp: idr handle
+ * @idr: idr handle
* @fn: function to be called for each pointer
- * @data: data passed back to callback function
+ * @data: data passed to callback function
*
- * Iterate over the pointers registered with the given idr. The
- * callback function will be called for each pointer currently
- * registered, passing the id, the pointer and the data pointer passed
- * to this function. It is not safe to modify the idr tree while in
- * the callback, so functions such as idr_get_new and idr_remove are
- * not allowed.
+ * The callback function will be called for each entry in @idr, passing
+ * the id, the pointer and the data pointer passed to this function.
*
- * We check the return of @fn each time. If it returns anything other
- * than %0, we break out and return that value.
+ * If @fn returns anything other than %0, the iteration stops and that
+ * value is returned from this function.
*
- * The caller must serialize idr_for_each() vs idr_get_new() and idr_remove().
+ * idr_for_each() can be called concurrently with idr_alloc() and
+ * idr_remove() if protected by RCU. Newly added entries may not be
+ * seen and deleted entries may be seen, but adding and removing entries
+ * will not cause other entries to be skipped, nor spurious ones to be seen.
*/
-int idr_for_each(struct idr *idp,
- int (*fn)(int id, void *p, void *data), void *data)
+int idr_for_each(const struct idr *idr,
+ int (*fn)(int id, void *p, void *data), void *data)
{
- int n, id, max, error = 0;
- struct idr_layer *p;
- struct idr_layer *pa[MAX_IDR_LEVEL + 1];
- struct idr_layer **paa = &pa[0];
-
- n = idp->layers * IDR_BITS;
- *paa = rcu_dereference_raw(idp->top);
- max = idr_max(idp->layers);
+ struct radix_tree_iter iter;
+ void __rcu **slot;
- id = 0;
- while (id >= 0 && id <= max) {
- p = *paa;
- while (n > 0 && p) {
- n -= IDR_BITS;
- p = rcu_dereference_raw(p->ary[(id >> n) & IDR_MASK]);
- *++paa = p;
- }
-
- if (p) {
- error = fn(id, (void *)p, data);
- if (error)
- break;
- }
-
- id += 1 << n;
- while (n < fls(id)) {
- n += IDR_BITS;
- --paa;
- }
+ radix_tree_for_each_slot(slot, &idr->idr_rt, &iter, 0) {
+ int ret = fn(iter.index, rcu_dereference_raw(*slot), data);
+ if (ret)
+ return ret;
}
- return error;
+ return 0;
}
EXPORT_SYMBOL(idr_for_each);
/**
- * idr_get_next - lookup next object of id to given id.
- * @idp: idr handle
- * @nextidp: pointer to lookup key
- *
- * Returns pointer to registered object with id, which is next number to
- * given id. After being looked up, *@nextidp will be updated for the next
- * iteration.
- *
- * This function can be called under rcu_read_lock(), given that the leaf
- * pointers lifetimes are correctly managed.
+ * idr_get_next - Find next populated entry
+ * @idr: idr handle
+ * @nextid: Pointer to lowest possible ID to return
+ *
+ * Returns the next populated entry in the tree with an ID greater than
+ * or equal to the value pointed to by @nextid. On exit, @nextid is updated
+ * to the ID of the found value. To use in a loop, the value pointed to by
+ * nextid must be incremented by the user.
*/
-void *idr_get_next(struct idr *idp, int *nextidp)
+void *idr_get_next(struct idr *idr, int *nextid)
{
- struct idr_layer *p, *pa[MAX_IDR_LEVEL + 1];
- struct idr_layer **paa = &pa[0];
- int id = *nextidp;
- int n, max;
+ struct radix_tree_iter iter;
+ void __rcu **slot;
- /* find first ent */
- p = *paa = rcu_dereference_raw(idp->top);
- if (!p)
+ slot = radix_tree_iter_find(&idr->idr_rt, &iter, *nextid);
+ if (!slot)
return NULL;
- n = (p->layer + 1) * IDR_BITS;
- max = idr_max(p->layer + 1);
-
- while (id >= 0 && id <= max) {
- p = *paa;
- while (n > 0 && p) {
- n -= IDR_BITS;
- p = rcu_dereference_raw(p->ary[(id >> n) & IDR_MASK]);
- *++paa = p;
- }
-
- if (p) {
- *nextidp = id;
- return p;
- }
- /*
- * Proceed to the next layer at the current level. Unlike
- * idr_for_each(), @id isn't guaranteed to be aligned to
- * layer boundary at this point and adding 1 << n may
- * incorrectly skip IDs. Make sure we jump to the
- * beginning of the next layer using round_up().
- */
- id = round_up(id + 1, 1 << n);
- while (n < fls(id)) {
- n += IDR_BITS;
- --paa;
- }
- }
- return NULL;
+ *nextid = iter.index;
+ return rcu_dereference_raw(*slot);
}
EXPORT_SYMBOL(idr_get_next);
-
/**
* idr_replace - replace pointer for given id
- * @idp: idr handle
- * @ptr: pointer you want associated with the id
- * @id: lookup key
+ * @idr: idr handle
+ * @ptr: New pointer to associate with the ID
+ * @id: Lookup key
*
- * Replace the pointer registered with an id and return the old value.
- * A %-ENOENT return indicates that @id was not found.
- * A %-EINVAL return indicates that @id was not within valid constraints.
+ * Replace the pointer registered with an ID and return the old value.
+ * This function can be called under the RCU read lock concurrently with
+ * idr_alloc() and idr_remove() (as long as the ID being removed is not
+ * the one being replaced!).
*
- * The caller must serialize with writers.
+ * Returns: 0 on success. %-ENOENT indicates that @id was not found.
+ * %-EINVAL indicates that @id or @ptr were not valid.
*/
-void *idr_replace(struct idr *idp, void *ptr, int id)
+void *idr_replace(struct idr *idr, void *ptr, int id)
{
- int n;
- struct idr_layer *p, *old_p;
+ struct radix_tree_node *node;
+ void __rcu **slot = NULL;
+ void *entry;
- if (id < 0)
+ if (WARN_ON_ONCE(id < 0))
+ return ERR_PTR(-EINVAL);
+ if (WARN_ON_ONCE(radix_tree_is_internal_node(ptr)))
return ERR_PTR(-EINVAL);
- p = idp->top;
- if (!p)
- return ERR_PTR(-ENOENT);
-
- if (id > idr_max(p->layer + 1))
- return ERR_PTR(-ENOENT);
-
- 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)))
+ entry = __radix_tree_lookup(&idr->idr_rt, id, &node, &slot);
+ if (!slot || radix_tree_tag_get(&idr->idr_rt, id, IDR_FREE))
return ERR_PTR(-ENOENT);
- old_p = p->ary[n];
- rcu_assign_pointer(p->ary[n], ptr);
+ __radix_tree_replace(&idr->idr_rt, node, slot, ptr, NULL, NULL);
- return old_p;
+ return entry;
}
EXPORT_SYMBOL(idr_replace);
-void __init idr_init_cache(void)
-{
- idr_layer_cache = kmem_cache_create("idr_layer_cache",
- sizeof(struct idr_layer), 0, SLAB_PANIC, NULL);
-}
-
-/**
- * idr_init - initialize idr handle
- * @idp: idr handle
- *
- * This function is use to set up the handle (@idp) that you will pass
- * to the rest of the functions.
- */
-void idr_init(struct idr *idp)
-{
- memset(idp, 0, sizeof(struct idr));
- spin_lock_init(&idp->lock);
-}
-EXPORT_SYMBOL(idr_init);
-
-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
- * IDA - IDR based ID allocator
*
- * This is id allocator without id -> pointer translation. Memory
- * usage is much lower than full blown idr because each id only
- * occupies a bit. ida uses a custom leaf node which contains
- * IDA_BITMAP_BITS slots.
- *
- * 2007-04-25 written by Tejun Heo <htejun@gmail.com>
+ * The IDA is an ID allocator which does not provide the ability to
+ * associate an ID with a pointer. As such, it only needs to store one
+ * bit per ID, and so is more space efficient than an IDR. To use an IDA,
+ * define it using DEFINE_IDA() (or embed a &struct ida in a data structure,
+ * then initialise it using ida_init()). To allocate a new ID, call
+ * ida_simple_get(). To free an ID, call ida_simple_remove().
+ *
+ * If you have more complex locking requirements, use a loop around
+ * ida_pre_get() and ida_get_new() to allocate a new ID. Then use
+ * ida_remove() to free an ID. You must make sure that ida_get_new() and
+ * ida_remove() cannot be called at the same time as each other for the
+ * same IDA.
+ *
+ * You can also use ida_get_new_above() if you need an ID to be allocated
+ * above a particular number. ida_destroy() can be used to dispose of an
+ * IDA without needing to free the individual IDs in it. You can use
+ * ida_is_empty() to find out whether the IDA has any IDs currently allocated.
+ *
+ * IDs are currently limited to the range [0-INT_MAX]. If this is an awkward
+ * limitation, it should be quite straightforward to raise the maximum.
*/
-static void free_bitmap(struct ida *ida, struct ida_bitmap *bitmap)
-{
- unsigned long flags;
-
- if (!ida->free_bitmap) {
- spin_lock_irqsave(&ida->idr.lock, flags);
- if (!ida->free_bitmap) {
- ida->free_bitmap = bitmap;
- bitmap = NULL;
- }
- spin_unlock_irqrestore(&ida->idr.lock, flags);
- }
-
- kfree(bitmap);
-}
-
-/**
- * ida_pre_get - reserve resources for ida allocation
- * @ida: ida handle
- * @gfp_mask: memory allocation flag
- *
- * This function should be called prior to locking and calling the
- * following function. It preallocates enough memory to satisfy the
- * worst possible allocation.
- *
- * If the system is REALLY out of memory this function returns %0,
- * otherwise %1.
+/*
+ * Developer's notes:
+ *
+ * The IDA uses the functionality provided by the IDR & radix tree to store
+ * bitmaps in each entry. The IDR_FREE tag means there is at least one bit
+ * free, unlike the IDR where it means at least one entry is free.
+ *
+ * I considered telling the radix tree that each slot is an order-10 node
+ * and storing the bit numbers in the radix tree, but the radix tree can't
+ * allow a single multiorder entry at index 0, which would significantly
+ * increase memory consumption for the IDA. So instead we divide the index
+ * by the number of bits in the leaf bitmap before doing a radix tree lookup.
+ *
+ * As an optimisation, if there are only a few low bits set in any given
+ * leaf, instead of allocating a 128-byte bitmap, we use the 'exceptional
+ * entry' functionality of the radix tree to store BITS_PER_LONG - 2 bits
+ * directly in the entry. By being really tricksy, we could store
+ * BITS_PER_LONG - 1 bits, but there're diminishing returns after optimising
+ * for 0-3 allocated IDs.
+ *
+ * We allow the radix tree 'exceptional' count to get out of date. Nothing
+ * in the IDA nor the radix tree code checks it. If it becomes important
+ * to maintain an accurate exceptional count, switch the rcu_assign_pointer()
+ * calls to radix_tree_iter_replace() which will correct the exceptional
+ * count.
+ *
+ * The IDA always requires a lock to alloc/free. If we add a 'test_bit'
+ * equivalent, it will still need locking. Going to RCU lookup would require
+ * using RCU to free bitmaps, and that's not trivial without embedding an
+ * RCU head in the bitmap, which adds a 2-pointer overhead to each 128-byte
+ * bitmap, which is excessive.
*/
-int ida_pre_get(struct ida *ida, gfp_t gfp_mask)
-{
- /* allocate idr_layers */
- if (!__idr_pre_get(&ida->idr, gfp_mask))
- return 0;
- /* allocate free_bitmap */
- if (!ida->free_bitmap) {
- struct ida_bitmap *bitmap;
-
- bitmap = kmalloc(sizeof(struct ida_bitmap), gfp_mask);
- if (!bitmap)
- return 0;
-
- free_bitmap(ida, bitmap);
- }
-
- return 1;
-}
-EXPORT_SYMBOL(ida_pre_get);
+#define IDA_MAX (0x80000000U / IDA_BITMAP_BITS)
/**
* ida_get_new_above - allocate new ID above or equal to a start id
- * @ida: ida handle
- * @starting_id: id to start search at
- * @p_id: pointer to the allocated handle
+ * @ida: ida handle
+ * @start: id to start search at
+ * @id: pointer to the allocated handle
*
- * Allocate new ID above or equal to @starting_id. It should be called
- * with any required locks.
+ * Allocate new ID above or equal to @start. It should be called
+ * with any required locks to ensure that concurrent calls to
+ * ida_get_new_above() / ida_get_new() / ida_remove() are not allowed.
+ * Consider using ida_simple_get() if you do not have complex locking
+ * requirements.
*
* If memory is required, it will return %-EAGAIN, you should unlock
* and go back to the ida_pre_get() call. If the ida is full, it will
- * return %-ENOSPC.
- *
- * Note that callers must ensure that concurrent access to @ida is not possible.
- * See ida_simple_get() for a varaint which takes care of locking.
+ * return %-ENOSPC. On success, it will return 0.
*
- * @p_id returns a value in the range @starting_id ... %0x7fffffff.
+ * @id returns a value in the range @start ... %0x7fffffff.
*/
-int ida_get_new_above(struct ida *ida, int starting_id, int *p_id)
+int ida_get_new_above(struct ida *ida, int start, int *id)
{
- struct idr_layer *pa[MAX_IDR_LEVEL + 1];
+ struct radix_tree_root *root = &ida->ida_rt;
+ void __rcu **slot;
+ struct radix_tree_iter iter;
struct ida_bitmap *bitmap;
- unsigned long flags;
- int idr_id = starting_id / IDA_BITMAP_BITS;
- int offset = starting_id % IDA_BITMAP_BITS;
- int t, id;
-
- restart:
- /* get vacant slot */
- t = idr_get_empty_slot(&ida->idr, idr_id, pa, 0, &ida->idr);
- if (t < 0)
- return t == -ENOMEM ? -EAGAIN : t;
-
- if (t * IDA_BITMAP_BITS >= MAX_IDR_BIT)
- return -ENOSPC;
-
- if (t != idr_id)
- offset = 0;
- idr_id = t;
-
- /* if bitmap isn't there, create a new one */
- bitmap = (void *)pa[0]->ary[idr_id & IDR_MASK];
- if (!bitmap) {
- spin_lock_irqsave(&ida->idr.lock, flags);
- bitmap = ida->free_bitmap;
- ida->free_bitmap = NULL;
- spin_unlock_irqrestore(&ida->idr.lock, flags);
-
- if (!bitmap)
- return -EAGAIN;
-
- memset(bitmap, 0, sizeof(struct ida_bitmap));
- rcu_assign_pointer(pa[0]->ary[idr_id & IDR_MASK],
- (void *)bitmap);
- pa[0]->count++;
- }
-
- /* lookup for empty slot */
- t = find_next_zero_bit(bitmap->bitmap, IDA_BITMAP_BITS, offset);
- if (t == IDA_BITMAP_BITS) {
- /* no empty slot after offset, continue to the next chunk */
- idr_id++;
- offset = 0;
- goto restart;
- }
-
- id = idr_id * IDA_BITMAP_BITS + t;
- if (id >= MAX_IDR_BIT)
- return -ENOSPC;
+ unsigned long index;
+ unsigned bit, ebit;
+ int new;
+
+ index = start / IDA_BITMAP_BITS;
+ bit = start % IDA_BITMAP_BITS;
+ ebit = bit + RADIX_TREE_EXCEPTIONAL_SHIFT;
+
+ slot = radix_tree_iter_init(&iter, index);
+ for (;;) {
+ if (slot)
+ slot = radix_tree_next_slot(slot, &iter,
+ RADIX_TREE_ITER_TAGGED);
+ if (!slot) {
+ slot = idr_get_free(root, &iter, GFP_NOWAIT, IDA_MAX);
+ if (IS_ERR(slot)) {
+ if (slot == ERR_PTR(-ENOMEM))
+ return -EAGAIN;
+ return PTR_ERR(slot);
+ }
+ }
+ if (iter.index > index) {
+ bit = 0;
+ ebit = RADIX_TREE_EXCEPTIONAL_SHIFT;
+ }
+ new = iter.index * IDA_BITMAP_BITS;
+ bitmap = rcu_dereference_raw(*slot);
+ if (radix_tree_exception(bitmap)) {
+ unsigned long tmp = (unsigned long)bitmap;
+ ebit = find_next_zero_bit(&tmp, BITS_PER_LONG, ebit);
+ if (ebit < BITS_PER_LONG) {
+ tmp |= 1UL << ebit;
+ rcu_assign_pointer(*slot, (void *)tmp);
+ *id = new + ebit - RADIX_TREE_EXCEPTIONAL_SHIFT;
+ return 0;
+ }
+ bitmap = this_cpu_xchg(ida_bitmap, NULL);
+ if (!bitmap)
+ return -EAGAIN;
+ memset(bitmap, 0, sizeof(*bitmap));
+ bitmap->bitmap[0] = tmp >> RADIX_TREE_EXCEPTIONAL_SHIFT;
+ rcu_assign_pointer(*slot, bitmap);
+ }
- __set_bit(t, bitmap->bitmap);
- if (++bitmap->nr_busy == IDA_BITMAP_BITS)
- idr_mark_full(pa, idr_id);
+ if (bitmap) {
+ bit = find_next_zero_bit(bitmap->bitmap,
+ IDA_BITMAP_BITS, bit);
+ new += bit;
+ if (new < 0)
+ return -ENOSPC;
+ if (bit == IDA_BITMAP_BITS)
+ continue;
- *p_id = id;
+ __set_bit(bit, bitmap->bitmap);
+ if (bitmap_full(bitmap->bitmap, IDA_BITMAP_BITS))
+ radix_tree_iter_tag_clear(root, &iter,
+ IDR_FREE);
+ } else {
+ new += bit;
+ if (new < 0)
+ return -ENOSPC;
+ if (ebit < BITS_PER_LONG) {
+ bitmap = (void *)((1UL << ebit) |
+ RADIX_TREE_EXCEPTIONAL_ENTRY);
+ radix_tree_iter_replace(root, &iter, slot,
+ bitmap);
+ *id = new;
+ return 0;
+ }
+ bitmap = this_cpu_xchg(ida_bitmap, NULL);
+ if (!bitmap)
+ return -EAGAIN;
+ memset(bitmap, 0, sizeof(*bitmap));
+ __set_bit(bit, bitmap->bitmap);
+ radix_tree_iter_replace(root, &iter, slot, bitmap);
+ }
- /* Each leaf node can handle nearly a thousand slots and the
- * whole idea of ida is to have small memory foot print.
- * Throw away extra resources one by one after each successful
- * allocation.
- */
- if (ida->idr.id_free_cnt || ida->free_bitmap) {
- struct idr_layer *p = get_from_free_list(&ida->idr);
- if (p)
- kmem_cache_free(idr_layer_cache, p);
+ *id = new;
+ return 0;
}
-
- return 0;
}
EXPORT_SYMBOL(ida_get_new_above);
/**
- * ida_remove - remove the given ID
- * @ida: ida handle
- * @id: ID to free
+ * ida_remove - Free the given ID
+ * @ida: ida handle
+ * @id: ID to free
+ *
+ * This function should not be called at the same time as ida_get_new_above().
*/
void ida_remove(struct ida *ida, int id)
{
- struct idr_layer *p = ida->idr.top;
- int shift = (ida->idr.layers - 1) * IDR_BITS;
- int idr_id = id / IDA_BITMAP_BITS;
- int offset = id % IDA_BITMAP_BITS;
- int n;
+ unsigned long index = id / IDA_BITMAP_BITS;
+ unsigned offset = id % IDA_BITMAP_BITS;
struct ida_bitmap *bitmap;
+ unsigned long *btmp;
+ struct radix_tree_iter iter;
+ void __rcu **slot;
- if (idr_id > idr_max(ida->idr.layers))
+ slot = radix_tree_iter_lookup(&ida->ida_rt, &iter, index);
+ if (!slot)
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);
- p = p->ary[n];
- shift -= IDR_BITS;
+ bitmap = rcu_dereference_raw(*slot);
+ if (radix_tree_exception(bitmap)) {
+ btmp = (unsigned long *)slot;
+ offset += RADIX_TREE_EXCEPTIONAL_SHIFT;
+ if (offset >= BITS_PER_LONG)
+ goto err;
+ } else {
+ btmp = bitmap->bitmap;
}
-
- if (p == NULL)
- goto err;
-
- n = idr_id & IDR_MASK;
- __clear_bit(n, p->bitmap);
-
- bitmap = (void *)p->ary[n];
- if (!bitmap || !test_bit(offset, bitmap->bitmap))
+ if (!test_bit(offset, btmp))
goto err;
- /* update bitmap and remove it if empty */
- __clear_bit(offset, bitmap->bitmap);
- if (--bitmap->nr_busy == 0) {
- __set_bit(n, p->bitmap); /* to please idr_remove() */
- idr_remove(&ida->idr, idr_id);
- free_bitmap(ida, bitmap);
+ __clear_bit(offset, btmp);
+ radix_tree_iter_tag_set(&ida->ida_rt, &iter, IDR_FREE);
+ if (radix_tree_exception(bitmap)) {
+ if (rcu_dereference_raw(*slot) ==
+ (void *)RADIX_TREE_EXCEPTIONAL_ENTRY)
+ radix_tree_iter_delete(&ida->ida_rt, &iter, slot);
+ } else if (bitmap_empty(btmp, IDA_BITMAP_BITS)) {
+ kfree(bitmap);
+ radix_tree_iter_delete(&ida->ida_rt, &iter, slot);
}
-
return;
-
err:
WARN(1, "ida_remove called for id=%d which is not allocated.\n", id);
}
EXPORT_SYMBOL(ida_remove);
/**
- * ida_destroy - release all cached layers within an ida tree
- * @ida: ida handle
+ * ida_destroy - Free the contents of an ida
+ * @ida: ida handle
+ *
+ * Calling this function releases all resources associated with an IDA. When
+ * this call returns, the IDA is empty and can be reused or freed. The caller
+ * should not allow ida_remove() or ida_get_new_above() to be called at the
+ * same time.
*/
void ida_destroy(struct ida *ida)
{
- idr_destroy(&ida->idr);
- kfree(ida->free_bitmap);
+ struct radix_tree_iter iter;
+ void __rcu **slot;
+
+ radix_tree_for_each_slot(slot, &ida->ida_rt, &iter, 0) {
+ struct ida_bitmap *bitmap = rcu_dereference_raw(*slot);
+ if (!radix_tree_exception(bitmap))
+ kfree(bitmap);
+ radix_tree_iter_delete(&ida->ida_rt, &iter, slot);
+ }
}
EXPORT_SYMBOL(ida_destroy);
spin_unlock_irqrestore(&simple_ida_lock, flags);
}
EXPORT_SYMBOL(ida_simple_remove);
-
-/**
- * ida_init - initialize ida handle
- * @ida: ida handle
- *
- * This function is use to set up the handle (@ida) that you will pass
- * to the rest of the functions.
- */
-void ida_init(struct ida *ida)
-{
- memset(ida, 0, sizeof(struct ida));
- idr_init(&ida->idr);
-
-}
-EXPORT_SYMBOL(ida_init);
projects / karo-tx-linux.git / blobdiff