xref: /openbmc/linux/lib/idr.c (revision ffcaafdb)
1 // SPDX-License-Identifier: GPL-2.0-only
2 #include <linux/bitmap.h>
3 #include <linux/bug.h>
4 #include <linux/export.h>
5 #include <linux/idr.h>
6 #include <linux/slab.h>
7 #include <linux/spinlock.h>
8 #include <linux/xarray.h>
9 
10 /**
11  * idr_alloc_u32() - Allocate an ID.
12  * @idr: IDR handle.
13  * @ptr: Pointer to be associated with the new ID.
14  * @nextid: Pointer to an ID.
15  * @max: The maximum ID to allocate (inclusive).
16  * @gfp: Memory allocation flags.
17  *
18  * Allocates an unused ID in the range specified by @nextid and @max.
19  * Note that @max is inclusive whereas the @end parameter to idr_alloc()
20  * is exclusive.  The new ID is assigned to @nextid before the pointer
21  * is inserted into the IDR, so if @nextid points into the object pointed
22  * to by @ptr, a concurrent lookup will not find an uninitialised ID.
23  *
24  * The caller should provide their own locking to ensure that two
25  * concurrent modifications to the IDR are not possible.  Read-only
26  * accesses to the IDR may be done under the RCU read lock or may
27  * exclude simultaneous writers.
28  *
29  * Return: 0 if an ID was allocated, -ENOMEM if memory allocation failed,
30  * or -ENOSPC if no free IDs could be found.  If an error occurred,
31  * @nextid is unchanged.
32  */
idr_alloc_u32(struct idr * idr,void * ptr,u32 * nextid,unsigned long max,gfp_t gfp)33 int idr_alloc_u32(struct idr *idr, void *ptr, u32 *nextid,
34 			unsigned long max, gfp_t gfp)
35 {
36 	struct radix_tree_iter iter;
37 	void __rcu **slot;
38 	unsigned int base = idr->idr_base;
39 	unsigned int id = *nextid;
40 
41 	if (WARN_ON_ONCE(!(idr->idr_rt.xa_flags & ROOT_IS_IDR)))
42 		idr->idr_rt.xa_flags |= IDR_RT_MARKER;
43 
44 	id = (id < base) ? 0 : id - base;
45 	radix_tree_iter_init(&iter, id);
46 	slot = idr_get_free(&idr->idr_rt, &iter, gfp, max - base);
47 	if (IS_ERR(slot))
48 		return PTR_ERR(slot);
49 
50 	*nextid = iter.index + base;
51 	/* there is a memory barrier inside radix_tree_iter_replace() */
52 	radix_tree_iter_replace(&idr->idr_rt, &iter, slot, ptr);
53 	radix_tree_iter_tag_clear(&idr->idr_rt, &iter, IDR_FREE);
54 
55 	return 0;
56 }
57 EXPORT_SYMBOL_GPL(idr_alloc_u32);
58 
59 /**
60  * idr_alloc() - Allocate an ID.
61  * @idr: IDR handle.
62  * @ptr: Pointer to be associated with the new ID.
63  * @start: The minimum ID (inclusive).
64  * @end: The maximum ID (exclusive).
65  * @gfp: Memory allocation flags.
66  *
67  * Allocates an unused ID in the range specified by @start and @end.  If
68  * @end is <= 0, it is treated as one larger than %INT_MAX.  This allows
69  * callers to use @start + N as @end as long as N is within integer range.
70  *
71  * The caller should provide their own locking to ensure that two
72  * concurrent modifications to the IDR are not possible.  Read-only
73  * accesses to the IDR may be done under the RCU read lock or may
74  * exclude simultaneous writers.
75  *
76  * Return: The newly allocated ID, -ENOMEM if memory allocation failed,
77  * or -ENOSPC if no free IDs could be found.
78  */
idr_alloc(struct idr * idr,void * ptr,int start,int end,gfp_t gfp)79 int idr_alloc(struct idr *idr, void *ptr, int start, int end, gfp_t gfp)
80 {
81 	u32 id = start;
82 	int ret;
83 
84 	if (WARN_ON_ONCE(start < 0))
85 		return -EINVAL;
86 
87 	ret = idr_alloc_u32(idr, ptr, &id, end > 0 ? end - 1 : INT_MAX, gfp);
88 	if (ret)
89 		return ret;
90 
91 	return id;
92 }
93 EXPORT_SYMBOL_GPL(idr_alloc);
94 
95 /**
96  * idr_alloc_cyclic() - Allocate an ID cyclically.
97  * @idr: IDR handle.
98  * @ptr: Pointer to be associated with the new ID.
99  * @start: The minimum ID (inclusive).
100  * @end: The maximum ID (exclusive).
101  * @gfp: Memory allocation flags.
102  *
103  * Allocates an unused ID in the range specified by @start and @end.  If
104  * @end is <= 0, it is treated as one larger than %INT_MAX.  This allows
105  * callers to use @start + N as @end as long as N is within integer range.
106  * The search for an unused ID will start at the last ID allocated and will
107  * wrap around to @start if no free IDs are found before reaching @end.
108  *
109  * The caller should provide their own locking to ensure that two
110  * concurrent modifications to the IDR are not possible.  Read-only
111  * accesses to the IDR may be done under the RCU read lock or may
112  * exclude simultaneous writers.
113  *
114  * Return: The newly allocated ID, -ENOMEM if memory allocation failed,
115  * or -ENOSPC if no free IDs could be found.
116  */
idr_alloc_cyclic(struct idr * idr,void * ptr,int start,int end,gfp_t gfp)117 int idr_alloc_cyclic(struct idr *idr, void *ptr, int start, int end, gfp_t gfp)
118 {
119 	u32 id = idr->idr_next;
120 	int err, max = end > 0 ? end - 1 : INT_MAX;
121 
122 	if ((int)id < start)
123 		id = start;
124 
125 	err = idr_alloc_u32(idr, ptr, &id, max, gfp);
126 	if ((err == -ENOSPC) && (id > start)) {
127 		id = start;
128 		err = idr_alloc_u32(idr, ptr, &id, max, gfp);
129 	}
130 	if (err)
131 		return err;
132 
133 	idr->idr_next = id + 1;
134 	return id;
135 }
136 EXPORT_SYMBOL(idr_alloc_cyclic);
137 
138 /**
139  * idr_remove() - Remove an ID from the IDR.
140  * @idr: IDR handle.
141  * @id: Pointer ID.
142  *
143  * Removes this ID from the IDR.  If the ID was not previously in the IDR,
144  * this function returns %NULL.
145  *
146  * Since this function modifies the IDR, the caller should provide their
147  * own locking to ensure that concurrent modification of the same IDR is
148  * not possible.
149  *
150  * Return: The pointer formerly associated with this ID.
151  */
idr_remove(struct idr * idr,unsigned long id)152 void *idr_remove(struct idr *idr, unsigned long id)
153 {
154 	return radix_tree_delete_item(&idr->idr_rt, id - idr->idr_base, NULL);
155 }
156 EXPORT_SYMBOL_GPL(idr_remove);
157 
158 /**
159  * idr_find() - Return pointer for given ID.
160  * @idr: IDR handle.
161  * @id: Pointer ID.
162  *
163  * Looks up the pointer associated with this ID.  A %NULL pointer may
164  * indicate that @id is not allocated or that the %NULL pointer was
165  * associated with this ID.
166  *
167  * This function can be called under rcu_read_lock(), given that the leaf
168  * pointers lifetimes are correctly managed.
169  *
170  * Return: The pointer associated with this ID.
171  */
idr_find(const struct idr * idr,unsigned long id)172 void *idr_find(const struct idr *idr, unsigned long id)
173 {
174 	return radix_tree_lookup(&idr->idr_rt, id - idr->idr_base);
175 }
176 EXPORT_SYMBOL_GPL(idr_find);
177 
178 /**
179  * idr_for_each() - Iterate through all stored pointers.
180  * @idr: IDR handle.
181  * @fn: Function to be called for each pointer.
182  * @data: Data passed to callback function.
183  *
184  * The callback function will be called for each entry in @idr, passing
185  * the ID, the entry and @data.
186  *
187  * If @fn returns anything other than %0, the iteration stops and that
188  * value is returned from this function.
189  *
190  * idr_for_each() can be called concurrently with idr_alloc() and
191  * idr_remove() if protected by RCU.  Newly added entries may not be
192  * seen and deleted entries may be seen, but adding and removing entries
193  * will not cause other entries to be skipped, nor spurious ones to be seen.
194  */
idr_for_each(const struct idr * idr,int (* fn)(int id,void * p,void * data),void * data)195 int idr_for_each(const struct idr *idr,
196 		int (*fn)(int id, void *p, void *data), void *data)
197 {
198 	struct radix_tree_iter iter;
199 	void __rcu **slot;
200 	int base = idr->idr_base;
201 
202 	radix_tree_for_each_slot(slot, &idr->idr_rt, &iter, 0) {
203 		int ret;
204 		unsigned long id = iter.index + base;
205 
206 		if (WARN_ON_ONCE(id > INT_MAX))
207 			break;
208 		ret = fn(id, rcu_dereference_raw(*slot), data);
209 		if (ret)
210 			return ret;
211 	}
212 
213 	return 0;
214 }
215 EXPORT_SYMBOL(idr_for_each);
216 
217 /**
218  * idr_get_next_ul() - Find next populated entry.
219  * @idr: IDR handle.
220  * @nextid: Pointer to an ID.
221  *
222  * Returns the next populated entry in the tree with an ID greater than
223  * or equal to the value pointed to by @nextid.  On exit, @nextid is updated
224  * to the ID of the found value.  To use in a loop, the value pointed to by
225  * nextid must be incremented by the user.
226  */
idr_get_next_ul(struct idr * idr,unsigned long * nextid)227 void *idr_get_next_ul(struct idr *idr, unsigned long *nextid)
228 {
229 	struct radix_tree_iter iter;
230 	void __rcu **slot;
231 	void *entry = NULL;
232 	unsigned long base = idr->idr_base;
233 	unsigned long id = *nextid;
234 
235 	id = (id < base) ? 0 : id - base;
236 	radix_tree_for_each_slot(slot, &idr->idr_rt, &iter, id) {
237 		entry = rcu_dereference_raw(*slot);
238 		if (!entry)
239 			continue;
240 		if (!xa_is_internal(entry))
241 			break;
242 		if (slot != &idr->idr_rt.xa_head && !xa_is_retry(entry))
243 			break;
244 		slot = radix_tree_iter_retry(&iter);
245 	}
246 	if (!slot)
247 		return NULL;
248 
249 	*nextid = iter.index + base;
250 	return entry;
251 }
252 EXPORT_SYMBOL(idr_get_next_ul);
253 
254 /**
255  * idr_get_next() - Find next populated entry.
256  * @idr: IDR handle.
257  * @nextid: Pointer to an ID.
258  *
259  * Returns the next populated entry in the tree with an ID greater than
260  * or equal to the value pointed to by @nextid.  On exit, @nextid is updated
261  * to the ID of the found value.  To use in a loop, the value pointed to by
262  * nextid must be incremented by the user.
263  */
idr_get_next(struct idr * idr,int * nextid)264 void *idr_get_next(struct idr *idr, int *nextid)
265 {
266 	unsigned long id = *nextid;
267 	void *entry = idr_get_next_ul(idr, &id);
268 
269 	if (WARN_ON_ONCE(id > INT_MAX))
270 		return NULL;
271 	*nextid = id;
272 	return entry;
273 }
274 EXPORT_SYMBOL(idr_get_next);
275 
276 /**
277  * idr_replace() - replace pointer for given ID.
278  * @idr: IDR handle.
279  * @ptr: New pointer to associate with the ID.
280  * @id: ID to change.
281  *
282  * Replace the pointer registered with an ID and return the old value.
283  * This function can be called under the RCU read lock concurrently with
284  * idr_alloc() and idr_remove() (as long as the ID being removed is not
285  * the one being replaced!).
286  *
287  * Returns: the old value on success.  %-ENOENT indicates that @id was not
288  * found.  %-EINVAL indicates that @ptr was not valid.
289  */
idr_replace(struct idr * idr,void * ptr,unsigned long id)290 void *idr_replace(struct idr *idr, void *ptr, unsigned long id)
291 {
292 	struct radix_tree_node *node;
293 	void __rcu **slot = NULL;
294 	void *entry;
295 
296 	id -= idr->idr_base;
297 
298 	entry = __radix_tree_lookup(&idr->idr_rt, id, &node, &slot);
299 	if (!slot || radix_tree_tag_get(&idr->idr_rt, id, IDR_FREE))
300 		return ERR_PTR(-ENOENT);
301 
302 	__radix_tree_replace(&idr->idr_rt, node, slot, ptr);
303 
304 	return entry;
305 }
306 EXPORT_SYMBOL(idr_replace);
307 
308 /**
309  * DOC: IDA description
310  *
311  * The IDA is an ID allocator which does not provide the ability to
312  * associate an ID with a pointer.  As such, it only needs to store one
313  * bit per ID, and so is more space efficient than an IDR.  To use an IDA,
314  * define it using DEFINE_IDA() (or embed a &struct ida in a data structure,
315  * then initialise it using ida_init()).  To allocate a new ID, call
316  * ida_alloc(), ida_alloc_min(), ida_alloc_max() or ida_alloc_range().
317  * To free an ID, call ida_free().
318  *
319  * ida_destroy() can be used to dispose of an IDA without needing to
320  * free the individual IDs in it.  You can use ida_is_empty() to find
321  * out whether the IDA has any IDs currently allocated.
322  *
323  * The IDA handles its own locking.  It is safe to call any of the IDA
324  * functions without synchronisation in your code.
325  *
326  * IDs are currently limited to the range [0-INT_MAX].  If this is an awkward
327  * limitation, it should be quite straightforward to raise the maximum.
328  */
329 
330 /*
331  * Developer's notes:
332  *
333  * The IDA uses the functionality provided by the XArray to store bitmaps in
334  * each entry.  The XA_FREE_MARK is only cleared when all bits in the bitmap
335  * have been set.
336  *
337  * I considered telling the XArray that each slot is an order-10 node
338  * and indexing by bit number, but the XArray can't allow a single multi-index
339  * entry in the head, which would significantly increase memory consumption
340  * for the IDA.  So instead we divide the index by the number of bits in the
341  * leaf bitmap before doing a radix tree lookup.
342  *
343  * As an optimisation, if there are only a few low bits set in any given
344  * leaf, instead of allocating a 128-byte bitmap, we store the bits
345  * as a value entry.  Value entries never have the XA_FREE_MARK cleared
346  * because we can always convert them into a bitmap entry.
347  *
348  * It would be possible to optimise further; once we've run out of a
349  * single 128-byte bitmap, we currently switch to a 576-byte node, put
350  * the 128-byte bitmap in the first entry and then start allocating extra
351  * 128-byte entries.  We could instead use the 512 bytes of the node's
352  * data as a bitmap before moving to that scheme.  I do not believe this
353  * is a worthwhile optimisation; Rasmus Villemoes surveyed the current
354  * users of the IDA and almost none of them use more than 1024 entries.
355  * Those that do use more than the 8192 IDs that the 512 bytes would
356  * provide.
357  *
358  * The IDA always uses a lock to alloc/free.  If we add a 'test_bit'
359  * equivalent, it will still need locking.  Going to RCU lookup would require
360  * using RCU to free bitmaps, and that's not trivial without embedding an
361  * RCU head in the bitmap, which adds a 2-pointer overhead to each 128-byte
362  * bitmap, which is excessive.
363  */
364 
365 /**
366  * ida_alloc_range() - Allocate an unused ID.
367  * @ida: IDA handle.
368  * @min: Lowest ID to allocate.
369  * @max: Highest ID to allocate.
370  * @gfp: Memory allocation flags.
371  *
372  * Allocate an ID between @min and @max, inclusive.  The allocated ID will
373  * not exceed %INT_MAX, even if @max is larger.
374  *
375  * Context: Any context. It is safe to call this function without
376  * locking in your code.
377  * Return: The allocated ID, or %-ENOMEM if memory could not be allocated,
378  * or %-ENOSPC if there are no free IDs.
379  */
ida_alloc_range(struct ida * ida,unsigned int min,unsigned int max,gfp_t gfp)380 int ida_alloc_range(struct ida *ida, unsigned int min, unsigned int max,
381 			gfp_t gfp)
382 {
383 	XA_STATE(xas, &ida->xa, min / IDA_BITMAP_BITS);
384 	unsigned bit = min % IDA_BITMAP_BITS;
385 	unsigned long flags;
386 	struct ida_bitmap *bitmap, *alloc = NULL;
387 
388 	if ((int)min < 0)
389 		return -ENOSPC;
390 
391 	if ((int)max < 0)
392 		max = INT_MAX;
393 
394 retry:
395 	xas_lock_irqsave(&xas, flags);
396 next:
397 	bitmap = xas_find_marked(&xas, max / IDA_BITMAP_BITS, XA_FREE_MARK);
398 	if (xas.xa_index > min / IDA_BITMAP_BITS)
399 		bit = 0;
400 	if (xas.xa_index * IDA_BITMAP_BITS + bit > max)
401 		goto nospc;
402 
403 	if (xa_is_value(bitmap)) {
404 		unsigned long tmp = xa_to_value(bitmap);
405 
406 		if (bit < BITS_PER_XA_VALUE) {
407 			bit = find_next_zero_bit(&tmp, BITS_PER_XA_VALUE, bit);
408 			if (xas.xa_index * IDA_BITMAP_BITS + bit > max)
409 				goto nospc;
410 			if (bit < BITS_PER_XA_VALUE) {
411 				tmp |= 1UL << bit;
412 				xas_store(&xas, xa_mk_value(tmp));
413 				goto out;
414 			}
415 		}
416 		bitmap = alloc;
417 		if (!bitmap)
418 			bitmap = kzalloc(sizeof(*bitmap), GFP_NOWAIT);
419 		if (!bitmap)
420 			goto alloc;
421 		bitmap->bitmap[0] = tmp;
422 		xas_store(&xas, bitmap);
423 		if (xas_error(&xas)) {
424 			bitmap->bitmap[0] = 0;
425 			goto out;
426 		}
427 	}
428 
429 	if (bitmap) {
430 		bit = find_next_zero_bit(bitmap->bitmap, IDA_BITMAP_BITS, bit);
431 		if (xas.xa_index * IDA_BITMAP_BITS + bit > max)
432 			goto nospc;
433 		if (bit == IDA_BITMAP_BITS)
434 			goto next;
435 
436 		__set_bit(bit, bitmap->bitmap);
437 		if (bitmap_full(bitmap->bitmap, IDA_BITMAP_BITS))
438 			xas_clear_mark(&xas, XA_FREE_MARK);
439 	} else {
440 		if (bit < BITS_PER_XA_VALUE) {
441 			bitmap = xa_mk_value(1UL << bit);
442 		} else {
443 			bitmap = alloc;
444 			if (!bitmap)
445 				bitmap = kzalloc(sizeof(*bitmap), GFP_NOWAIT);
446 			if (!bitmap)
447 				goto alloc;
448 			__set_bit(bit, bitmap->bitmap);
449 		}
450 		xas_store(&xas, bitmap);
451 	}
452 out:
453 	xas_unlock_irqrestore(&xas, flags);
454 	if (xas_nomem(&xas, gfp)) {
455 		xas.xa_index = min / IDA_BITMAP_BITS;
456 		bit = min % IDA_BITMAP_BITS;
457 		goto retry;
458 	}
459 	if (bitmap != alloc)
460 		kfree(alloc);
461 	if (xas_error(&xas))
462 		return xas_error(&xas);
463 	return xas.xa_index * IDA_BITMAP_BITS + bit;
464 alloc:
465 	xas_unlock_irqrestore(&xas, flags);
466 	alloc = kzalloc(sizeof(*bitmap), gfp);
467 	if (!alloc)
468 		return -ENOMEM;
469 	xas_set(&xas, min / IDA_BITMAP_BITS);
470 	bit = min % IDA_BITMAP_BITS;
471 	goto retry;
472 nospc:
473 	xas_unlock_irqrestore(&xas, flags);
474 	kfree(alloc);
475 	return -ENOSPC;
476 }
477 EXPORT_SYMBOL(ida_alloc_range);
478 
479 /**
480  * ida_free() - Release an allocated ID.
481  * @ida: IDA handle.
482  * @id: Previously allocated ID.
483  *
484  * Context: Any context. It is safe to call this function without
485  * locking in your code.
486  */
ida_free(struct ida * ida,unsigned int id)487 void ida_free(struct ida *ida, unsigned int id)
488 {
489 	XA_STATE(xas, &ida->xa, id / IDA_BITMAP_BITS);
490 	unsigned bit = id % IDA_BITMAP_BITS;
491 	struct ida_bitmap *bitmap;
492 	unsigned long flags;
493 
494 	if ((int)id < 0)
495 		return;
496 
497 	xas_lock_irqsave(&xas, flags);
498 	bitmap = xas_load(&xas);
499 
500 	if (xa_is_value(bitmap)) {
501 		unsigned long v = xa_to_value(bitmap);
502 		if (bit >= BITS_PER_XA_VALUE)
503 			goto err;
504 		if (!(v & (1UL << bit)))
505 			goto err;
506 		v &= ~(1UL << bit);
507 		if (!v)
508 			goto delete;
509 		xas_store(&xas, xa_mk_value(v));
510 	} else {
511 		if (!bitmap || !test_bit(bit, bitmap->bitmap))
512 			goto err;
513 		__clear_bit(bit, bitmap->bitmap);
514 		xas_set_mark(&xas, XA_FREE_MARK);
515 		if (bitmap_empty(bitmap->bitmap, IDA_BITMAP_BITS)) {
516 			kfree(bitmap);
517 delete:
518 			xas_store(&xas, NULL);
519 		}
520 	}
521 	xas_unlock_irqrestore(&xas, flags);
522 	return;
523  err:
524 	xas_unlock_irqrestore(&xas, flags);
525 	WARN(1, "ida_free called for id=%d which is not allocated.\n", id);
526 }
527 EXPORT_SYMBOL(ida_free);
528 
529 /**
530  * ida_destroy() - Free all IDs.
531  * @ida: IDA handle.
532  *
533  * Calling this function frees all IDs and releases all resources used
534  * by an IDA.  When this call returns, the IDA is empty and can be reused
535  * or freed.  If the IDA is already empty, there is no need to call this
536  * function.
537  *
538  * Context: Any context. It is safe to call this function without
539  * locking in your code.
540  */
ida_destroy(struct ida * ida)541 void ida_destroy(struct ida *ida)
542 {
543 	XA_STATE(xas, &ida->xa, 0);
544 	struct ida_bitmap *bitmap;
545 	unsigned long flags;
546 
547 	xas_lock_irqsave(&xas, flags);
548 	xas_for_each(&xas, bitmap, ULONG_MAX) {
549 		if (!xa_is_value(bitmap))
550 			kfree(bitmap);
551 		xas_store(&xas, NULL);
552 	}
553 	xas_unlock_irqrestore(&xas, flags);
554 }
555 EXPORT_SYMBOL(ida_destroy);
556 
557 #ifndef __KERNEL__
558 extern void xa_dump_index(unsigned long index, unsigned int shift);
559 #define IDA_CHUNK_SHIFT		ilog2(IDA_BITMAP_BITS)
560 
ida_dump_entry(void * entry,unsigned long index)561 static void ida_dump_entry(void *entry, unsigned long index)
562 {
563 	unsigned long i;
564 
565 	if (!entry)
566 		return;
567 
568 	if (xa_is_node(entry)) {
569 		struct xa_node *node = xa_to_node(entry);
570 		unsigned int shift = node->shift + IDA_CHUNK_SHIFT +
571 			XA_CHUNK_SHIFT;
572 
573 		xa_dump_index(index * IDA_BITMAP_BITS, shift);
574 		xa_dump_node(node);
575 		for (i = 0; i < XA_CHUNK_SIZE; i++)
576 			ida_dump_entry(node->slots[i],
577 					index | (i << node->shift));
578 	} else if (xa_is_value(entry)) {
579 		xa_dump_index(index * IDA_BITMAP_BITS, ilog2(BITS_PER_LONG));
580 		pr_cont("value: data %lx [%px]\n", xa_to_value(entry), entry);
581 	} else {
582 		struct ida_bitmap *bitmap = entry;
583 
584 		xa_dump_index(index * IDA_BITMAP_BITS, IDA_CHUNK_SHIFT);
585 		pr_cont("bitmap: %p data", bitmap);
586 		for (i = 0; i < IDA_BITMAP_LONGS; i++)
587 			pr_cont(" %lx", bitmap->bitmap[i]);
588 		pr_cont("\n");
589 	}
590 }
591 
ida_dump(struct ida * ida)592 static void ida_dump(struct ida *ida)
593 {
594 	struct xarray *xa = &ida->xa;
595 	pr_debug("ida: %p node %p free %d\n", ida, xa->xa_head,
596 				xa->xa_flags >> ROOT_TAG_SHIFT);
597 	ida_dump_entry(xa->xa_head, 0);
598 }
599 #endif
600