* 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().
+ * ida_alloc(), ida_alloc_min(), ida_alloc_max() or ida_alloc_range().
+ * To free an ID, call ida_free().
*
- * 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.
+ * 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.
#define IDA_MAX (0x80000000U / IDA_BITMAP_BITS - 1)
-/**
- * ida_get_new_above - allocate new ID above or equal to a start id
- * @ida: ida handle
- * @start: id to start search at
- * @id: pointer to the allocated handle
- *
- * 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. On success, it will return 0.
- *
- * @id returns a value in the range @start ... %0x7fffffff.
- */
-int ida_get_new_above(struct ida *ida, int start, int *id)
+static int ida_get_new_above(struct ida *ida, int start)
{
struct radix_tree_root *root = &ida->ida_rt;
void __rcu **slot;
if (ebit < BITS_PER_LONG) {
tmp |= 1UL << ebit;
rcu_assign_pointer(*slot, (void *)tmp);
- *id = new + ebit - RADIX_TREE_EXCEPTIONAL_SHIFT;
- return 0;
+ return new + ebit -
+ RADIX_TREE_EXCEPTIONAL_SHIFT;
}
bitmap = this_cpu_xchg(ida_bitmap, NULL);
if (!bitmap)
RADIX_TREE_EXCEPTIONAL_ENTRY);
radix_tree_iter_replace(root, &iter, slot,
bitmap);
- *id = new;
- return 0;
+ return new;
}
bitmap = this_cpu_xchg(ida_bitmap, NULL);
if (!bitmap)
radix_tree_iter_replace(root, &iter, slot, bitmap);
}
- *id = new;
- return 0;
+ return new;
}
}
-EXPORT_SYMBOL(ida_get_new_above);
-/**
- * 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)
+static void ida_remove(struct ida *ida, int id)
{
unsigned long index = id / IDA_BITMAP_BITS;
unsigned offset = id % IDA_BITMAP_BITS;
}
return;
err:
- WARN(1, "ida_remove called for id=%d which is not allocated.\n", id);
+ WARN(1, "ida_free called for id=%d which is not allocated.\n", id);
}
-EXPORT_SYMBOL(ida_remove);
/**
- * ida_destroy - Free the contents of an ida
- * @ida: ida handle
+ * ida_destroy() - Free all IDs.
+ * @ida: IDA handle.
+ *
+ * Calling this function frees all IDs and releases all resources used
+ * by an IDA. When this call returns, the IDA is empty and can be reused
+ * or freed. If the IDA is already empty, there is no need to call this
+ * function.
*
- * 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.
+ * Context: Any context.
*/
void ida_destroy(struct ida *ida)
{
+ unsigned long flags;
struct radix_tree_iter iter;
void __rcu **slot;
+ xa_lock_irqsave(&ida->ida_rt, flags);
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);
}
+ xa_unlock_irqrestore(&ida->ida_rt, flags);
}
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.
+ * ida_alloc_range() - Allocate an unused ID.
+ * @ida: IDA handle.
+ * @min: Lowest ID to allocate.
+ * @max: Highest ID to allocate.
+ * @gfp: Memory allocation flags.
*
- * Compared to ida_get_new_above() this function does its own locking, and
- * should be used unless there are special requirements.
+ * Allocate an ID between @min and @max, inclusive. The allocated ID will
+ * not exceed %INT_MAX, even if @max is larger.
*
- * Use ida_simple_remove() to get rid of an id.
+ * Context: Any context.
+ * Return: The allocated ID, or %-ENOMEM if memory could not be allocated,
+ * or %-ENOSPC if there are no free IDs.
*/
-int ida_simple_get(struct ida *ida, unsigned int start, unsigned int end,
- gfp_t gfp_mask)
+int ida_alloc_range(struct ida *ida, unsigned int min, unsigned int max,
+ gfp_t gfp)
{
- int ret, id;
- unsigned int max;
+ int id = 0;
unsigned long flags;
- BUG_ON((int)start < 0);
- BUG_ON((int)end < 0);
+ if ((int)min < 0)
+ return -ENOSPC;
- if (end == 0)
- max = 0x80000000;
- else {
- BUG_ON(end < start);
- max = end - 1;
- }
+ if ((int)max < 0)
+ max = INT_MAX;
again:
- if (!ida_pre_get(ida, gfp_mask))
- return -ENOMEM;
-
xa_lock_irqsave(&ida->ida_rt, flags);
- ret = ida_get_new_above(ida, start, &id);
- if (!ret) {
- if (id > max) {
- ida_remove(ida, id);
- ret = -ENOSPC;
- } else {
- ret = id;
- }
+ id = ida_get_new_above(ida, min);
+ if (id > (int)max) {
+ ida_remove(ida, id);
+ id = -ENOSPC;
}
xa_unlock_irqrestore(&ida->ida_rt, flags);
- if (unlikely(ret == -EAGAIN))
+ if (unlikely(id == -EAGAIN)) {
+ if (!ida_pre_get(ida, gfp))
+ return -ENOMEM;
goto again;
+ }
- return ret;
+ return id;
}
-EXPORT_SYMBOL(ida_simple_get);
+EXPORT_SYMBOL(ida_alloc_range);
/**
- * ida_simple_remove - remove an allocated id.
- * @ida: the (initialized) ida.
- * @id: the id returned by ida_simple_get.
- *
- * Use to release an id allocated with ida_simple_get().
+ * ida_free() - Release an allocated ID.
+ * @ida: IDA handle.
+ * @id: Previously allocated ID.
*
- * Compared to ida_remove() this function does its own locking, and should be
- * used unless there are special requirements.
+ * Context: Any context.
*/
-void ida_simple_remove(struct ida *ida, unsigned int id)
+void ida_free(struct ida *ida, unsigned int id)
{
unsigned long flags;
ida_remove(ida, id);
xa_unlock_irqrestore(&ida->ida_rt, flags);
}
-EXPORT_SYMBOL(ida_simple_remove);
+EXPORT_SYMBOL(ida_free);
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