* Modified by George Anzinger to reuse immediately and to use
* find bit instructions. Also removed _irq on spinlocks.
*
- * Small id to pointer translation service.
+ * Modified by Nadia Derbey to make it RCU safe.
*
- * It uses a radix tree like structure as a sparse array indexed
+ * 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.
+ * 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
+ * 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
+ * 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.
*/
#include <linux/init.h>
#include <linux/module.h>
#endif
+#include <linux/err.h>
#include <linux/string.h>
#include <linux/idr.h>
+#include <linux/spinlock.h>
-static kmem_cache_t *idr_layer_cache;
+static struct kmem_cache *idr_layer_cache;
+static DEFINE_SPINLOCK(simple_ida_lock);
-static struct idr_layer *alloc_layer(struct idr *idp)
+static struct idr_layer *get_from_free_list(struct idr *idp)
{
struct idr_layer *p;
+ unsigned long flags;
- spin_lock(&idp->lock);
+ 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(&idp->lock);
+ spin_unlock_irqrestore(&idp->lock, flags);
return(p);
}
-static void free_layer(struct idr *idp, struct idr_layer *p)
+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_layer *p)
+{
+ 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)
{
- /*
- * Depends on the return element being zeroed.
- */
- spin_lock(&idp->lock);
p->ary[0] = idp->id_free;
idp->id_free = p;
idp->id_free_cnt++;
- spin_unlock(&idp->lock);
+}
+
+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 (p->bitmap == IDR_FULL) {
+ if (!(p = pa[++l]))
+ break;
+ id = id >> IDR_BITS;
+ __set_bit((id & IDR_MASK), &p->bitmap);
+ }
}
/**
- * idr_pre_get - reserver resources for idr allocation
+ * idr_pre_get - reserve resources for idr allocation
* @idp: idr handle
* @gfp_mask: memory allocation flags
*
- * This function should be called prior to locking and calling the
- * following function. It preallocates enough memory to satisfy
- * the worst possible allocation.
+ * 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.
+ * If the system is REALLY out of memory this function returns %0,
+ * otherwise %1.
*/
-int idr_pre_get(struct idr *idp, unsigned gfp_mask)
+int idr_pre_get(struct idr *idp, gfp_t gfp_mask)
{
while (idp->id_free_cnt < IDR_FREE_MAX) {
struct idr_layer *new;
- new = kmem_cache_alloc(idr_layer_cache, gfp_mask);
- if(new == NULL)
+ new = kmem_cache_zalloc(idr_layer_cache, gfp_mask);
+ if (new == NULL)
return (0);
- free_layer(idp, new);
+ move_to_free_list(idp, new);
}
return 1;
}
EXPORT_SYMBOL(idr_pre_get);
-static int sub_alloc(struct idr *idp, void *ptr, int *starting_id)
+static int sub_alloc(struct idr *idp, int *starting_id, struct idr_layer **pa)
{
int n, m, sh;
struct idr_layer *p, *new;
- struct idr_layer *pa[MAX_LEVEL];
- int l, id;
- long bm;
+ int l, id, oid;
+ unsigned long bm;
id = *starting_id;
+ restart:
p = idp->top;
l = idp->layers;
pa[l--] = NULL;
if (m == IDR_SIZE) {
/* no space available go back to previous layer. */
l++;
- id = (id | ((1 << (IDR_BITS*l))-1)) + 1;
- if (!(p = pa[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 -2;
+ return IDR_NEED_TO_GROW;
}
- continue;
+ 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_ID_BIT) || (id < 0))
- return -3;
+ return IDR_NOMORE_SPACE;
if (l == 0)
break;
/*
* Create the layer below if it is missing.
*/
if (!p->ary[m]) {
- if (!(new = alloc_layer(idp)))
+ new = get_from_free_list(idp);
+ if (!new)
return -1;
- p->ary[m] = new;
+ new->layer = l-1;
+ rcu_assign_pointer(p->ary[m], new);
p->count++;
}
pa[l--] = p;
p = p->ary[m];
}
- /*
- * We have reached the leaf node, plant the
- * users pointer and return the raw id.
- */
- p->ary[m] = (struct idr_layer *)ptr;
- __set_bit(m, &p->bitmap);
- p->count++;
- /*
- * 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.
- */
- n = id;
- while (p->bitmap == IDR_FULL) {
- if (!(p = pa[++l]))
- break;
- n = n >> IDR_BITS;
- __set_bit((n & IDR_MASK), &p->bitmap);
- }
- return(id);
+
+ pa[l] = p;
+ return id;
}
-static int idr_get_new_above_int(struct idr *idp, void *ptr, int starting_id)
+static int idr_get_empty_slot(struct idr *idp, int starting_id,
+ struct idr_layer **pa)
{
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 = alloc_layer(idp)))
+ if (!(p = get_from_free_list(idp)))
return -1;
+ p->layer = 0;
layers = 1;
}
/*
*/
while ((layers < (MAX_LEVEL - 1)) && (id >= (1 << (layers*IDR_BITS)))) {
layers++;
- if (!p->count)
+ if (!p->count) {
+ /* special case: if the tree is currently empty,
+ * then we grow the tree by moving the top node
+ * upwards.
+ */
+ p->layer++;
continue;
- if (!(new = alloc_layer(idp))) {
+ }
+ if (!(new = get_from_free_list(idp))) {
/*
* 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->bitmap = new->count = 0;
- free_layer(idp, new);
+ __move_to_free_list(idp, new);
}
+ spin_unlock_irqrestore(&idp->lock, flags);
return -1;
}
new->ary[0] = p;
new->count = 1;
+ new->layer = layers-1;
if (p->bitmap == IDR_FULL)
__set_bit(0, &new->bitmap);
p = new;
}
- idp->top = p;
+ rcu_assign_pointer(idp->top, p);
idp->layers = layers;
- v = sub_alloc(idp, ptr, &id);
- if (v == -2)
+ v = sub_alloc(idp, &id, pa);
+ if (v == IDR_NEED_TO_GROW)
goto build_up;
return(v);
}
+static int idr_get_new_above_int(struct idr *idp, void *ptr, int starting_id)
+{
+ struct idr_layer *pa[MAX_LEVEL];
+ int id;
+
+ 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;
+}
+
/**
* 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 ide
- * @start_id: id to start search at
+ * @ptr: pointer you want associated with the id
+ * @starting_id: id to start search at
* @id: pointer to the allocated handle
*
* This is the allocate id function. 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.
+ * 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.
*
- * @id returns a value in the range 0 ... 0x7fffffff
+ * If the idr is full idr_get_new_above() will return %-ENOSPC.
+ *
+ * @id returns a value in the range @starting_id ... %0x7fffffff
*/
int idr_get_new_above(struct idr *idp, void *ptr, int starting_id, int *id)
{
int rv;
+
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.
*/
- if (rv < 0) {
- if (rv == -1)
- return -EAGAIN;
- else /* Will be -3 */
- return -ENOSPC;
- }
+ if (rv < 0)
+ return _idr_rc_to_errno(rv);
*id = rv;
return 0;
}
/**
* idr_get_new - allocate new idr entry
* @idp: idr handle
- * @ptr: pointer you want associated with the ide
+ * @ptr: pointer you want associated with the id
* @id: pointer to the allocated handle
*
- * This is the allocate id function. It should be called with any
- * required locks.
+ * 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.
*
- * 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.
+ * If the idr is full idr_get_new_above() will return %-ENOSPC.
*
- * @id returns a value in the range 0 ... 0x7fffffff
+ * @id returns a value in the range %0 ... %0x7fffffff
*/
int idr_get_new(struct idr *idp, void *ptr, int *id)
{
int rv;
+
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) {
- if (rv == -1)
- return -EAGAIN;
- else /* Will be -3 */
- return -ENOSPC;
- }
+ if (rv < 0)
+ return _idr_rc_to_errno(rv);
*id = rv;
return 0;
}
static void idr_remove_warning(int id)
{
- printk("idr_remove called for id=%d which is not allocated.\n", id);
+ printk(KERN_WARNING
+ "idr_remove called for id=%d which is not allocated.\n", id);
dump_stack();
}
struct idr_layer *p = idp->top;
struct idr_layer **pa[MAX_LEVEL];
struct idr_layer ***paa = &pa[0];
+ struct idr_layer *to_free;
int n;
*paa = NULL;
n = id & IDR_MASK;
if (likely(p != NULL && test_bit(n, &p->bitmap))){
__clear_bit(n, &p->bitmap);
- p->ary[n] = NULL;
+ rcu_assign_pointer(p->ary[n], NULL);
+ to_free = NULL;
while(*paa && ! --((**paa)->count)){
- free_layer(idp, **paa);
+ if (to_free)
+ free_layer(to_free);
+ to_free = **paa;
**paa-- = NULL;
}
- if ( ! *paa )
+ if (!*paa)
idp->layers = 0;
- } else {
+ if (to_free)
+ free_layer(to_free);
+ } else
idr_remove_warning(id);
- }
}
/**
- * idr_remove - remove the given id and free it's slot
- * idp: idr handle
- * id: uniqueue key
+ * 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;
/* Mask off upper bits we don't use for the search. */
id &= MAX_ID_MASK;
sub_remove(idp, (idp->layers - 1) * IDR_BITS, id);
- if ( idp->top && idp->top->count == 1 &&
- (idp->layers > 1) &&
- idp->top->ary[0]){ // We can drop a layer
-
+ 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];
- idp->top->bitmap = idp->top->count = 0;
- free_layer(idp, idp->top);
- idp->top = p;
+ rcu_assign_pointer(idp->top, p);
--idp->layers;
+ to_free->bitmap = to_free->count = 0;
+ free_layer(to_free);
}
while (idp->id_free_cnt >= IDR_FREE_MAX) {
-
- p = alloc_layer(idp);
+ 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;
}
+ 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)
+{
+ int n, id, max;
+ int bt_mask;
+ struct idr_layer *p;
+ struct idr_layer *pa[MAX_LEVEL];
+ struct idr_layer **paa = &pa[0];
+
+ n = idp->layers * IDR_BITS;
+ p = idp->top;
+ rcu_assign_pointer(idp->top, NULL);
+ max = 1 << n;
+
+ id = 0;
+ while (id < max) {
+ while (n > IDR_BITS && p) {
+ n -= IDR_BITS;
+ *paa++ = p;
+ p = p->ary[(id >> n) & IDR_MASK];
+ }
+
+ 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 (p)
+ free_layer(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
+ * @idp: idr handle
*/
void idr_destroy(struct idr *idp)
{
while (idp->id_free_cnt) {
- struct idr_layer *p = alloc_layer(idp);
+ struct idr_layer *p = get_from_free_list(idp);
kmem_cache_free(idr_layer_cache, p);
}
}
* return indicates that @id is not valid or you passed %NULL in
* idr_get_new().
*
- * The caller must serialize idr_find() vs idr_get_new() and idr_remove().
+ * 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)
{
int n;
struct idr_layer *p;
- n = idp->layers * IDR_BITS;
- p = idp->top;
+ 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))
return NULL;
+ BUG_ON(n == 0);
while (n > 0 && p) {
n -= IDR_BITS;
- p = p->ary[(id >> n) & IDR_MASK];
+ BUG_ON(n != p->layer*IDR_BITS);
+ p = rcu_dereference_raw(p->ary[(id >> n) & IDR_MASK]);
}
return((void *)p);
}
EXPORT_SYMBOL(idr_find);
-static void idr_cache_ctor(void * idr_layer,
- kmem_cache_t *idr_layer_cache, unsigned long flags)
+/**
+ * idr_for_each - iterate through all stored pointers
+ * @idp: idr handle
+ * @fn: function to be called for each pointer
+ * @data: data passed back 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.
+ *
+ * We check the return of @fn each time. If it returns anything other
+ * than %0, we break out and return that value.
+ *
+ * The caller must serialize idr_for_each() vs idr_get_new() and idr_remove().
+ */
+int idr_for_each(struct idr *idp,
+ int (*fn)(int id, void *p, void *data), void *data)
{
- memset(idr_layer, 0, sizeof(struct idr_layer));
+ int n, id, max, error = 0;
+ struct idr_layer *p;
+ struct idr_layer *pa[MAX_LEVEL];
+ struct idr_layer **paa = &pa[0];
+
+ n = idp->layers * IDR_BITS;
+ p = rcu_dereference_raw(idp->top);
+ max = 1 << n;
+
+ id = 0;
+ while (id < max) {
+ while (n > 0 && p) {
+ n -= IDR_BITS;
+ *paa++ = p;
+ p = rcu_dereference_raw(p->ary[(id >> n) & IDR_MASK]);
+ }
+
+ if (p) {
+ error = fn(id, (void *)p, data);
+ if (error)
+ break;
+ }
+
+ id += 1 << n;
+ while (n < fls(id)) {
+ n += IDR_BITS;
+ p = *--paa;
+ }
+ }
+
+ return error;
}
+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.
+ */
-static int init_id_cache(void)
+void *idr_get_next(struct idr *idp, int *nextidp)
{
- if (!idr_layer_cache)
- idr_layer_cache = kmem_cache_create("idr_layer_cache",
- sizeof(struct idr_layer), 0, 0, idr_cache_ctor, NULL);
- return 0;
+ struct idr_layer *p, *pa[MAX_LEVEL];
+ 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;
+
+ while (id < max) {
+ while (n > 0 && p) {
+ n -= IDR_BITS;
+ *paa++ = p;
+ p = rcu_dereference_raw(p->ary[(id >> n) & IDR_MASK]);
+ }
+
+ if (p) {
+ *nextidp = id;
+ return p;
+ }
+
+ id += 1 << n;
+ while (n < fls(id)) {
+ n += IDR_BITS;
+ p = *--paa;
+ }
+ }
+ return NULL;
+}
+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
+ *
+ * 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.
+ *
+ * The caller must serialize with writers.
+ */
+void *idr_replace(struct idr *idp, void *ptr, int id)
+{
+ int n;
+ struct idr_layer *p, *old_p;
+
+ p = idp->top;
+ if (!p)
+ return ERR_PTR(-EINVAL);
+
+ n = (p->layer+1) * IDR_BITS;
+
+ id &= MAX_ID_MASK;
+
+ if (id >= (1 << n))
+ return ERR_PTR(-EINVAL);
+
+ n -= 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)))
+ return ERR_PTR(-ENOENT);
+
+ old_p = p->ary[n];
+ rcu_assign_pointer(p->ary[n], ptr);
+
+ return old_p;
+}
+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);
}
/**
*/
void idr_init(struct idr *idp)
{
- init_id_cache();
memset(idp, 0, sizeof(struct idr));
spin_lock_init(&idp->lock);
}
EXPORT_SYMBOL(idr_init);
+
+
+/**
+ * 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>
+ */
+
+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.
+ */
+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);
+
+/**
+ * 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
+ *
+ * Allocate new ID above or equal to @ida. 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
+ * return %-ENOSPC.
+ *
+ * @p_id returns a value in the range @starting_id ... %0x7fffffff.
+ */
+int ida_get_new_above(struct ida *ida, int starting_id, int *p_id)
+{
+ struct idr_layer *pa[MAX_LEVEL];
+ 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);
+ if (t < 0)
+ return _idr_rc_to_errno(t);
+
+ if (t * IDA_BITMAP_BITS >= MAX_ID_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_ID_BIT)
+ return -ENOSPC;
+
+ __set_bit(t, bitmap->bitmap);
+ if (++bitmap->nr_busy == IDA_BITMAP_BITS)
+ idr_mark_full(pa, idr_id);
+
+ *p_id = id;
+
+ /* 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);
+ }
+
+ return 0;
+}
+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
+ */
+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;
+ struct ida_bitmap *bitmap;
+
+ /* 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;
+ }
+
+ if (p == NULL)
+ goto err;
+
+ n = idr_id & IDR_MASK;
+ __clear_bit(n, &p->bitmap);
+
+ bitmap = (void *)p->ary[n];
+ if (!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() */
+ idr_remove(&ida->idr, idr_id);
+ free_bitmap(ida, bitmap);
+ }
+
+ return;
+
+ err:
+ printk(KERN_WARNING
+ "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
+ */
+void ida_destroy(struct ida *ida)
+{
+ idr_destroy(&ida->idr);
+ kfree(ida->free_bitmap);
+}
+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;
+
+ 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(&simple_ida_lock);
+ ret = ida_get_new_above(ida, start, &id);
+ if (!ret) {
+ if (id > max) {
+ ida_remove(ida, id);
+ ret = -ENOSPC;
+ } else {
+ ret = id;
+ }
+ }
+ spin_unlock(&simple_ida_lock);
+
+ 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)
+{
+ BUG_ON((int)id < 0);
+ spin_lock(&simple_ida_lock);
+ ida_remove(ida, id);
+ spin_unlock(&simple_ida_lock);
+}
+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);
Code Review / linux-2.6.git / blobdiff