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ida: Lock the IDA in ida_destroy

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The user has no need to handle locking between ida_simple_get() and
ida_simple_remove().  They shouldn't be forced to think about whether
ida_destroy() might be called at the same time as any of their other
IDA manipulation calls.  Improve the documnetation while I'm in here.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
This commit is contained in:
Matthew Wilcox 2018-06-21 15:36:45 -04:00
parent 76f070b413
commit 50d97d5071
1 changed files with 11 additions and 6 deletions
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17
lib/idr.c
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@ -523,25 +523,30 @@ void ida_remove(struct ida *ida, int id)
EXPORT_SYMBOL(ida_remove); EXPORT_SYMBOL(ida_remove);
/** /**
* ida_destroy - Free the contents of an ida * ida_destroy() - Free all IDs.
* @ida: ida handle * @ida: IDA handle.
* *
* Calling this function releases all resources associated with an IDA. When * Calling this function frees all IDs and releases all resources used
* this call returns, the IDA is empty and can be reused or freed. The caller * by an IDA. When this call returns, the IDA is empty and can be reused
* should not allow ida_remove() or ida_get_new_above() to be called at the * or freed. If the IDA is already empty, there is no need to call this
* same time. * function.
*
* Context: Any context.
*/ */
void ida_destroy(struct ida *ida) void ida_destroy(struct ida *ida)
{ {
unsigned long flags;
struct radix_tree_iter iter; struct radix_tree_iter iter;
void __rcu **slot; void __rcu **slot;
xa_lock_irqsave(&ida->ida_rt, flags);
radix_tree_for_each_slot(slot, &ida->ida_rt, &iter, 0) { radix_tree_for_each_slot(slot, &ida->ida_rt, &iter, 0) {
struct ida_bitmap *bitmap = rcu_dereference_raw(*slot); struct ida_bitmap *bitmap = rcu_dereference_raw(*slot);
if (!radix_tree_exception(bitmap)) if (!radix_tree_exception(bitmap))
kfree(bitmap); kfree(bitmap);
radix_tree_iter_delete(&ida->ida_rt, &iter, slot); radix_tree_iter_delete(&ida->ida_rt, &iter, slot);
} }
xa_unlock_irqrestore(&ida->ida_rt, flags);
} }
EXPORT_SYMBOL(ida_destroy); EXPORT_SYMBOL(ida_destroy);