#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>
static struct kmem_cache *idr_layer_cache;
+static DEFINE_SPINLOCK(simple_ida_lock);
static struct idr_layer *get_from_free_list(struct idr *idp)
{
return(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)
{
}
/**
- * 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
- * idr_get_new* functions. 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, 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);
+ new = kmem_cache_zalloc(idr_layer_cache, gfp_mask);
if (new == NULL)
return (0);
move_to_free_list(idp, new);
id = (id | ((1 << (IDR_BITS * l)) - 1)) + 1;
/* if already at the top layer, we need to grow */
- if (!(p = pa[l])) {
+ if (id >= 1 << (idp->layers * IDR_BITS)) {
*starting_id = id;
return IDR_NEED_TO_GROW;
}
+ p = pa[l];
+ BUG_ON(!p);
/* If we need to go up one layer, continue the
* loop; otherwise, restart from the top.
new = get_from_free_list(idp);
if (!new)
return -1;
+ new->layer = l-1;
rcu_assign_pointer(p->ary[m], new);
p->count++;
}
if (unlikely(!p)) {
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 = get_from_free_list(idp))) {
/*
* The allocation failed. If we built part of
}
new->ary[0] = p;
new->count = 1;
+ new->layer = layers-1;
if (p->bitmap == IDR_FULL)
__set_bit(0, &new->bitmap);
p = new;
/**
* 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)
{
/**
* 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)
{
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)){
- move_to_free_list(idp, **paa);
+ if (to_free)
+ free_layer(to_free);
+ to_free = **paa;
**paa-- = NULL;
}
if (!*paa)
idp->layers = 0;
+ if (to_free)
+ free_layer(to_free);
} else
idr_remove_warning(id);
}
/**
- * idr_remove - remove the given id and free it's slot
+ * 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
-
+ 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;
- move_to_free_list(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 = 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;
* 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
+ * 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;
p = p->ary[(id >> n) & IDR_MASK];
}
+ bt_mask = id;
id += 1 << n;
- while (n < fls(id)) {
- if (p) {
- memset(p, 0, sizeof *p);
- move_to_free_list(idp, p);
- }
+ /* 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->top = NULL;
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)
{
* 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);
}
* not allowed.
*
* We check the return of @fn each time. If it returns anything other
- * than 0, we break out and return that value.
+ * than %0, we break out and return that value.
*
* The caller must serialize idr_for_each() vs idr_get_new() and idr_remove().
*/
struct idr_layer **paa = &pa[0];
n = idp->layers * IDR_BITS;
- p = idp->top;
+ p = rcu_dereference_raw(idp->top);
max = 1 << n;
id = 0;
while (n > 0 && p) {
n -= IDR_BITS;
*paa++ = p;
- p = p->ary[(id >> n) & IDR_MASK];
+ p = rcu_dereference_raw(p->ary[(id >> n) & IDR_MASK]);
}
if (p) {
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.
+ */
+void *idr_get_next(struct idr *idp, int *nextidp)
+{
+ struct idr_layer *p, *pa[MAX_LEVEL];
+ struct idr_layer **paa = &pa[0];
+ int id = *nextidp;
+ int n, max;
+
+ /* find first ent */
+ p = rcu_dereference_raw(idp->top);
+ if (!p)
+ return NULL;
+ n = (p->layer + 1) * IDR_BITS;
+ max = 1 << n;
+
+ 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.
+ * A %-ENOENT return indicates that @id was not found.
+ * A %-EINVAL return indicates that @id was not within valid constraints.
*
- * The caller must serialize vs idr_find(), idr_get_new(), and idr_remove().
+ * The caller must serialize with writers.
*/
void *idr_replace(struct idr *idp, void *ptr, int id)
{
int n;
struct idr_layer *p, *old_p;
- n = idp->layers * IDR_BITS;
p = idp->top;
+ if (!p)
+ return ERR_PTR(-EINVAL);
+
+ n = (p->layer+1) * IDR_BITS;
id &= MAX_ID_MASK;
return ERR_PTR(-ENOENT);
old_p = p->ary[n];
- p->ary[n] = ptr;
+ rcu_assign_pointer(p->ary[n], ptr);
return old_p;
}
EXPORT_SYMBOL(idr_replace);
-static void idr_cache_ctor(struct kmem_cache *idr_layer_cache, void *idr_layer)
-{
- memset(idr_layer, 0, sizeof(struct idr_layer));
-}
-
void __init idr_init_cache(void)
{
idr_layer_cache = kmem_cache_create("idr_layer_cache",
- sizeof(struct idr_layer), 0, SLAB_PANIC,
- idr_cache_ctor);
+ sizeof(struct idr_layer), 0, SLAB_PANIC, NULL);
}
/**
EXPORT_SYMBOL(idr_init);
-/*
+/**
+ * DOC: IDA description
* IDA - IDR based ID allocator
*
- * this is id allocator without id -> pointer translation. Memory
+ * 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.
* 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.
+ * 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)
{
/**
* ida_get_new_above - allocate new ID above or equal to a start id
* @ida: ida handle
- * @staring_id: id to start search at
+ * @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
+ * 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.
+ * return %-ENOSPC.
*
- * @p_id returns a value in the range 0 ... 0x7fffffff.
+ * @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)
{
*
* Allocate new ID. It should be called with any required locks.
*
- * If memory is required, it will return -EAGAIN, you should unlock
+ * 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.
+ * return %-ENOSPC.
*
- * @id returns a value in the range 0 ... 0x7fffffff.
+ * @p_id returns a value in the range %0 ... %0x7fffffff.
*/
int ida_get_new(struct ida *ida, int *p_id)
{
/**
* ida_destroy - release all cached layers within an ida tree
- * ida: ida handle
+ * @ida: ida handle
*/
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
*
projects / linux-flexiantxendom0-3.2.10.git / blobdiff