// SPDX-License-Identifier: GPL-2.0+
  /*
   * test_xarray.c: Test the XArray API
   * Copyright (c) 2017-2018 Microsoft Corporation

   * Copyright (c) 2019-2020 Oracle

   * Author: Matthew Wilcox <willy@infradead.org>
   */
  
  #include <linux/xarray.h>
  #include <linux/module.h>
  
  static unsigned int tests_run;
  static unsigned int tests_passed;

  static const unsigned int order_limit =
  		IS_ENABLED(CONFIG_XARRAY_MULTI) ? BITS_PER_LONG : 1;

  #ifndef XA_DEBUG
  # ifdef __KERNEL__
  void xa_dump(const struct xarray *xa) { }
  # endif
  #undef XA_BUG_ON
  #define XA_BUG_ON(xa, x) do {					\
  	tests_run++;						\
  	if (x) {						\
  		printk("BUG at %s:%d
  ", __func__, __LINE__);	\
  		xa_dump(xa);					\
  		dump_stack();					\
  	} else {						\
  		tests_passed++;					\
  	}							\
  } while (0)
  #endif

  static void *xa_mk_index(unsigned long index)
  {
  	return xa_mk_value(index & LONG_MAX);
  }

  static void *xa_store_index(struct xarray *xa, unsigned long index, gfp_t gfp)
  {

  	return xa_store(xa, index, xa_mk_index(index), gfp);

  }

  static void xa_insert_index(struct xarray *xa, unsigned long index)
  {
  	XA_BUG_ON(xa, xa_insert(xa, index, xa_mk_index(index),
  				GFP_KERNEL) != 0);
  }

  static void xa_alloc_index(struct xarray *xa, unsigned long index, gfp_t gfp)
  {

  	u32 id;

  	XA_BUG_ON(xa, xa_alloc(xa, &id, xa_mk_index(index), xa_limit_32b,

  				gfp) != 0);
  	XA_BUG_ON(xa, id != index);
  }

  static void xa_erase_index(struct xarray *xa, unsigned long index)
  {

  	XA_BUG_ON(xa, xa_erase(xa, index) != xa_mk_index(index));

  	XA_BUG_ON(xa, xa_load(xa, index) != NULL);
  }
  
  /*
   * If anyone needs this, please move it to xarray.c.  We have no current
   * users outside the test suite because all current multislot users want
   * to use the advanced API.
   */
  static void *xa_store_order(struct xarray *xa, unsigned long index,
  		unsigned order, void *entry, gfp_t gfp)
  {
  	XA_STATE_ORDER(xas, xa, index, order);
  	void *curr;
  
  	do {
  		xas_lock(&xas);
  		curr = xas_store(&xas, entry);
  		xas_unlock(&xas);
  	} while (xas_nomem(&xas, gfp));
  
  	return curr;
  }
  
  static noinline void check_xa_err(struct xarray *xa)
  {
  	XA_BUG_ON(xa, xa_err(xa_store_index(xa, 0, GFP_NOWAIT)) != 0);
  	XA_BUG_ON(xa, xa_err(xa_erase(xa, 0)) != 0);
  #ifndef __KERNEL__
  	/* The kernel does not fail GFP_NOWAIT allocations */
  	XA_BUG_ON(xa, xa_err(xa_store_index(xa, 1, GFP_NOWAIT)) != -ENOMEM);
  	XA_BUG_ON(xa, xa_err(xa_store_index(xa, 1, GFP_NOWAIT)) != -ENOMEM);
  #endif
  	XA_BUG_ON(xa, xa_err(xa_store_index(xa, 1, GFP_KERNEL)) != 0);
  	XA_BUG_ON(xa, xa_err(xa_store(xa, 1, xa_mk_value(0), GFP_KERNEL)) != 0);
  	XA_BUG_ON(xa, xa_err(xa_erase(xa, 1)) != 0);
  // kills the test-suite :-(
  //	XA_BUG_ON(xa, xa_err(xa_store(xa, 0, xa_mk_internal(0), 0)) != -EINVAL);

  }

  static noinline void check_xas_retry(struct xarray *xa)
  {
  	XA_STATE(xas, xa, 0);
  	void *entry;
  
  	xa_store_index(xa, 0, GFP_KERNEL);
  	xa_store_index(xa, 1, GFP_KERNEL);
  
  	rcu_read_lock();
  	XA_BUG_ON(xa, xas_find(&xas, ULONG_MAX) != xa_mk_value(0));
  	xa_erase_index(xa, 1);
  	XA_BUG_ON(xa, !xa_is_retry(xas_reload(&xas)));
  	XA_BUG_ON(xa, xas_retry(&xas, NULL));
  	XA_BUG_ON(xa, xas_retry(&xas, xa_mk_value(0)));
  	xas_reset(&xas);
  	XA_BUG_ON(xa, xas.xa_node != XAS_RESTART);
  	XA_BUG_ON(xa, xas_next_entry(&xas, ULONG_MAX) != xa_mk_value(0));
  	XA_BUG_ON(xa, xas.xa_node != NULL);

  	rcu_read_unlock();

  
  	XA_BUG_ON(xa, xa_store_index(xa, 1, GFP_KERNEL) != NULL);

  
  	rcu_read_lock();

  	XA_BUG_ON(xa, !xa_is_internal(xas_reload(&xas)));
  	xas.xa_node = XAS_RESTART;
  	XA_BUG_ON(xa, xas_next_entry(&xas, ULONG_MAX) != xa_mk_value(0));
  	rcu_read_unlock();
  
  	/* Make sure we can iterate through retry entries */
  	xas_lock(&xas);
  	xas_set(&xas, 0);
  	xas_store(&xas, XA_RETRY_ENTRY);
  	xas_set(&xas, 1);
  	xas_store(&xas, XA_RETRY_ENTRY);
  
  	xas_set(&xas, 0);
  	xas_for_each(&xas, entry, ULONG_MAX) {

  		xas_store(&xas, xa_mk_index(xas.xa_index));

  	}
  	xas_unlock(&xas);
  
  	xa_erase_index(xa, 0);
  	xa_erase_index(xa, 1);
  }

  static noinline void check_xa_load(struct xarray *xa)
  {
  	unsigned long i, j;
  
  	for (i = 0; i < 1024; i++) {
  		for (j = 0; j < 1024; j++) {
  			void *entry = xa_load(xa, j);
  			if (j < i)
  				XA_BUG_ON(xa, xa_to_value(entry) != j);
  			else
  				XA_BUG_ON(xa, entry);
  		}
  		XA_BUG_ON(xa, xa_store_index(xa, i, GFP_KERNEL) != NULL);
  	}
  
  	for (i = 0; i < 1024; i++) {
  		for (j = 0; j < 1024; j++) {
  			void *entry = xa_load(xa, j);
  			if (j >= i)
  				XA_BUG_ON(xa, xa_to_value(entry) != j);
  			else
  				XA_BUG_ON(xa, entry);
  		}
  		xa_erase_index(xa, i);
  	}
  	XA_BUG_ON(xa, !xa_empty(xa));
  }

  static noinline void check_xa_mark_1(struct xarray *xa, unsigned long index)
  {

  	unsigned int order;
  	unsigned int max_order = IS_ENABLED(CONFIG_XARRAY_MULTI) ? 8 : 1;

  	/* NULL elements have no marks set */
  	XA_BUG_ON(xa, xa_get_mark(xa, index, XA_MARK_0));
  	xa_set_mark(xa, index, XA_MARK_0);
  	XA_BUG_ON(xa, xa_get_mark(xa, index, XA_MARK_0));
  
  	/* Storing a pointer will not make a mark appear */
  	XA_BUG_ON(xa, xa_store_index(xa, index, GFP_KERNEL) != NULL);
  	XA_BUG_ON(xa, xa_get_mark(xa, index, XA_MARK_0));
  	xa_set_mark(xa, index, XA_MARK_0);
  	XA_BUG_ON(xa, !xa_get_mark(xa, index, XA_MARK_0));
  
  	/* Setting one mark will not set another mark */
  	XA_BUG_ON(xa, xa_get_mark(xa, index + 1, XA_MARK_0));
  	XA_BUG_ON(xa, xa_get_mark(xa, index, XA_MARK_1));
  
  	/* Storing NULL clears marks, and they can't be set again */
  	xa_erase_index(xa, index);
  	XA_BUG_ON(xa, !xa_empty(xa));
  	XA_BUG_ON(xa, xa_get_mark(xa, index, XA_MARK_0));
  	xa_set_mark(xa, index, XA_MARK_0);
  	XA_BUG_ON(xa, xa_get_mark(xa, index, XA_MARK_0));

  
  	/*
  	 * Storing a multi-index entry over entries with marks gives the
  	 * entire entry the union of the marks
  	 */
  	BUG_ON((index % 4) != 0);
  	for (order = 2; order < max_order; order++) {
  		unsigned long base = round_down(index, 1UL << order);
  		unsigned long next = base + (1UL << order);
  		unsigned long i;
  
  		XA_BUG_ON(xa, xa_store_index(xa, index + 1, GFP_KERNEL));
  		xa_set_mark(xa, index + 1, XA_MARK_0);
  		XA_BUG_ON(xa, xa_store_index(xa, index + 2, GFP_KERNEL));

  		xa_set_mark(xa, index + 2, XA_MARK_2);

  		XA_BUG_ON(xa, xa_store_index(xa, next, GFP_KERNEL));

  		xa_store_order(xa, index, order, xa_mk_index(index),

  				GFP_KERNEL);
  		for (i = base; i < next; i++) {

  			XA_STATE(xas, xa, i);
  			unsigned int seen = 0;
  			void *entry;

  			XA_BUG_ON(xa, !xa_get_mark(xa, i, XA_MARK_0));

  			XA_BUG_ON(xa, xa_get_mark(xa, i, XA_MARK_1));
  			XA_BUG_ON(xa, !xa_get_mark(xa, i, XA_MARK_2));

  
  			/* We should see two elements in the array */

  			rcu_read_lock();

  			xas_for_each(&xas, entry, ULONG_MAX)
  				seen++;

  			rcu_read_unlock();

  			XA_BUG_ON(xa, seen != 2);
  
  			/* One of which is marked */
  			xas_set(&xas, 0);
  			seen = 0;

  			rcu_read_lock();

  			xas_for_each_marked(&xas, entry, ULONG_MAX, XA_MARK_0)
  				seen++;

  			rcu_read_unlock();

  			XA_BUG_ON(xa, seen != 1);

  		}
  		XA_BUG_ON(xa, xa_get_mark(xa, next, XA_MARK_0));
  		XA_BUG_ON(xa, xa_get_mark(xa, next, XA_MARK_1));
  		XA_BUG_ON(xa, xa_get_mark(xa, next, XA_MARK_2));
  		xa_erase_index(xa, index);
  		xa_erase_index(xa, next);
  		XA_BUG_ON(xa, !xa_empty(xa));
  	}
  	XA_BUG_ON(xa, !xa_empty(xa));

  }

  static noinline void check_xa_mark_2(struct xarray *xa)
  {
  	XA_STATE(xas, xa, 0);
  	unsigned long index;
  	unsigned int count = 0;
  	void *entry;
  
  	xa_store_index(xa, 0, GFP_KERNEL);
  	xa_set_mark(xa, 0, XA_MARK_0);
  	xas_lock(&xas);
  	xas_load(&xas);
  	xas_init_marks(&xas);
  	xas_unlock(&xas);
  	XA_BUG_ON(xa, !xa_get_mark(xa, 0, XA_MARK_0) == 0);
  
  	for (index = 3500; index < 4500; index++) {
  		xa_store_index(xa, index, GFP_KERNEL);
  		xa_set_mark(xa, index, XA_MARK_0);
  	}
  
  	xas_reset(&xas);
  	rcu_read_lock();
  	xas_for_each_marked(&xas, entry, ULONG_MAX, XA_MARK_0)
  		count++;
  	rcu_read_unlock();
  	XA_BUG_ON(xa, count != 1000);
  
  	xas_lock(&xas);
  	xas_for_each(&xas, entry, ULONG_MAX) {
  		xas_init_marks(&xas);
  		XA_BUG_ON(xa, !xa_get_mark(xa, xas.xa_index, XA_MARK_0));
  		XA_BUG_ON(xa, !xas_get_mark(&xas, XA_MARK_0));
  	}
  	xas_unlock(&xas);
  
  	xa_destroy(xa);
  }

  static noinline void check_xa_mark_3(struct xarray *xa)
  {
  #ifdef CONFIG_XARRAY_MULTI
  	XA_STATE(xas, xa, 0x41);
  	void *entry;
  	int count = 0;
  
  	xa_store_order(xa, 0x40, 2, xa_mk_index(0x40), GFP_KERNEL);
  	xa_set_mark(xa, 0x41, XA_MARK_0);
  
  	rcu_read_lock();
  	xas_for_each_marked(&xas, entry, ULONG_MAX, XA_MARK_0) {
  		count++;
  		XA_BUG_ON(xa, entry != xa_mk_index(0x40));
  	}
  	XA_BUG_ON(xa, count != 1);
  	rcu_read_unlock();
  	xa_destroy(xa);
  #endif
  }

  static noinline void check_xa_mark(struct xarray *xa)
  {
  	unsigned long index;
  
  	for (index = 0; index < 16384; index += 4)
  		check_xa_mark_1(xa, index);

  
  	check_xa_mark_2(xa);

  	check_xa_mark_3(xa);

  }

  static noinline void check_xa_shrink(struct xarray *xa)
  {
  	XA_STATE(xas, xa, 1);
  	struct xa_node *node;

  	unsigned int order;
  	unsigned int max_order = IS_ENABLED(CONFIG_XARRAY_MULTI) ? 15 : 1;

  
  	XA_BUG_ON(xa, !xa_empty(xa));
  	XA_BUG_ON(xa, xa_store_index(xa, 0, GFP_KERNEL) != NULL);
  	XA_BUG_ON(xa, xa_store_index(xa, 1, GFP_KERNEL) != NULL);
  
  	/*
  	 * Check that erasing the entry at 1 shrinks the tree and properly
  	 * marks the node as being deleted.
  	 */
  	xas_lock(&xas);
  	XA_BUG_ON(xa, xas_load(&xas) != xa_mk_value(1));
  	node = xas.xa_node;
  	XA_BUG_ON(xa, xa_entry_locked(xa, node, 0) != xa_mk_value(0));
  	XA_BUG_ON(xa, xas_store(&xas, NULL) != xa_mk_value(1));
  	XA_BUG_ON(xa, xa_load(xa, 1) != NULL);
  	XA_BUG_ON(xa, xas.xa_node != XAS_BOUNDS);
  	XA_BUG_ON(xa, xa_entry_locked(xa, node, 0) != XA_RETRY_ENTRY);
  	XA_BUG_ON(xa, xas_load(&xas) != NULL);
  	xas_unlock(&xas);
  	XA_BUG_ON(xa, xa_load(xa, 0) != xa_mk_value(0));
  	xa_erase_index(xa, 0);
  	XA_BUG_ON(xa, !xa_empty(xa));

  
  	for (order = 0; order < max_order; order++) {
  		unsigned long max = (1UL << order) - 1;
  		xa_store_order(xa, 0, order, xa_mk_value(0), GFP_KERNEL);
  		XA_BUG_ON(xa, xa_load(xa, max) != xa_mk_value(0));
  		XA_BUG_ON(xa, xa_load(xa, max + 1) != NULL);
  		rcu_read_lock();
  		node = xa_head(xa);
  		rcu_read_unlock();
  		XA_BUG_ON(xa, xa_store_index(xa, ULONG_MAX, GFP_KERNEL) !=
  				NULL);
  		rcu_read_lock();
  		XA_BUG_ON(xa, xa_head(xa) == node);
  		rcu_read_unlock();
  		XA_BUG_ON(xa, xa_load(xa, max + 1) != NULL);
  		xa_erase_index(xa, ULONG_MAX);
  		XA_BUG_ON(xa, xa->xa_head != node);
  		xa_erase_index(xa, 0);
  	}

  }

  static noinline void check_insert(struct xarray *xa)
  {
  	unsigned long i;
  
  	for (i = 0; i < 1024; i++) {
  		xa_insert_index(xa, i);
  		XA_BUG_ON(xa, xa_load(xa, i - 1) != NULL);
  		XA_BUG_ON(xa, xa_load(xa, i + 1) != NULL);
  		xa_erase_index(xa, i);
  	}
  
  	for (i = 10; i < BITS_PER_LONG; i++) {
  		xa_insert_index(xa, 1UL << i);
  		XA_BUG_ON(xa, xa_load(xa, (1UL << i) - 1) != NULL);
  		XA_BUG_ON(xa, xa_load(xa, (1UL << i) + 1) != NULL);
  		xa_erase_index(xa, 1UL << i);
  
  		xa_insert_index(xa, (1UL << i) - 1);
  		XA_BUG_ON(xa, xa_load(xa, (1UL << i) - 2) != NULL);
  		XA_BUG_ON(xa, xa_load(xa, 1UL << i) != NULL);
  		xa_erase_index(xa, (1UL << i) - 1);
  	}
  
  	xa_insert_index(xa, ~0UL);
  	XA_BUG_ON(xa, xa_load(xa, 0UL) != NULL);
  	XA_BUG_ON(xa, xa_load(xa, ~1UL) != NULL);
  	xa_erase_index(xa, ~0UL);
  
  	XA_BUG_ON(xa, !xa_empty(xa));
  }

  static noinline void check_cmpxchg(struct xarray *xa)
  {
  	void *FIVE = xa_mk_value(5);
  	void *SIX = xa_mk_value(6);
  	void *LOTS = xa_mk_value(12345678);
  
  	XA_BUG_ON(xa, !xa_empty(xa));
  	XA_BUG_ON(xa, xa_store_index(xa, 12345678, GFP_KERNEL) != NULL);

  	XA_BUG_ON(xa, xa_insert(xa, 12345678, xa, GFP_KERNEL) != -EBUSY);

  	XA_BUG_ON(xa, xa_cmpxchg(xa, 12345678, SIX, FIVE, GFP_KERNEL) != LOTS);
  	XA_BUG_ON(xa, xa_cmpxchg(xa, 12345678, LOTS, FIVE, GFP_KERNEL) != LOTS);
  	XA_BUG_ON(xa, xa_cmpxchg(xa, 12345678, FIVE, LOTS, GFP_KERNEL) != FIVE);
  	XA_BUG_ON(xa, xa_cmpxchg(xa, 5, FIVE, NULL, GFP_KERNEL) != NULL);
  	XA_BUG_ON(xa, xa_cmpxchg(xa, 5, NULL, FIVE, GFP_KERNEL) != NULL);

  	XA_BUG_ON(xa, xa_insert(xa, 5, FIVE, GFP_KERNEL) != -EBUSY);
  	XA_BUG_ON(xa, xa_cmpxchg(xa, 5, FIVE, NULL, GFP_KERNEL) != FIVE);
  	XA_BUG_ON(xa, xa_insert(xa, 5, FIVE, GFP_KERNEL) == -EBUSY);

  	xa_erase_index(xa, 12345678);
  	xa_erase_index(xa, 5);
  	XA_BUG_ON(xa, !xa_empty(xa));
  }

  static noinline void check_reserve(struct xarray *xa)
  {
  	void *entry;

  	unsigned long index;

  	int count;

  
  	/* An array with a reserved entry is not empty */
  	XA_BUG_ON(xa, !xa_empty(xa));

  	XA_BUG_ON(xa, xa_reserve(xa, 12345678, GFP_KERNEL) != 0);

  	XA_BUG_ON(xa, xa_empty(xa));
  	XA_BUG_ON(xa, xa_load(xa, 12345678));
  	xa_release(xa, 12345678);
  	XA_BUG_ON(xa, !xa_empty(xa));
  
  	/* Releasing a used entry does nothing */

  	XA_BUG_ON(xa, xa_reserve(xa, 12345678, GFP_KERNEL) != 0);

  	XA_BUG_ON(xa, xa_store_index(xa, 12345678, GFP_NOWAIT) != NULL);
  	xa_release(xa, 12345678);
  	xa_erase_index(xa, 12345678);
  	XA_BUG_ON(xa, !xa_empty(xa));

  	/* cmpxchg sees a reserved entry as ZERO */

  	XA_BUG_ON(xa, xa_reserve(xa, 12345678, GFP_KERNEL) != 0);

  	XA_BUG_ON(xa, xa_cmpxchg(xa, 12345678, XA_ZERO_ENTRY,
  				xa_mk_value(12345678), GFP_NOWAIT) != NULL);

  	xa_release(xa, 12345678);
  	xa_erase_index(xa, 12345678);
  	XA_BUG_ON(xa, !xa_empty(xa));

  	/* xa_insert treats it as busy */

  	XA_BUG_ON(xa, xa_reserve(xa, 12345678, GFP_KERNEL) != 0);

  	XA_BUG_ON(xa, xa_insert(xa, 12345678, xa_mk_value(12345678), 0) !=

  			-EBUSY);

  	XA_BUG_ON(xa, xa_empty(xa));
  	XA_BUG_ON(xa, xa_erase(xa, 12345678) != NULL);

  	XA_BUG_ON(xa, !xa_empty(xa));

  	/* Can iterate through a reserved entry */
  	xa_store_index(xa, 5, GFP_KERNEL);

  	XA_BUG_ON(xa, xa_reserve(xa, 6, GFP_KERNEL) != 0);

  	xa_store_index(xa, 7, GFP_KERNEL);

  	count = 0;

  	xa_for_each(xa, index, entry) {

  		XA_BUG_ON(xa, index != 5 && index != 7);

  		count++;
  	}
  	XA_BUG_ON(xa, count != 2);
  
  	/* If we free a reserved entry, we should be able to allocate it */
  	if (xa->xa_flags & XA_FLAGS_ALLOC) {
  		u32 id;
  
  		XA_BUG_ON(xa, xa_alloc(xa, &id, xa_mk_value(8),
  					XA_LIMIT(5, 10), GFP_KERNEL) != 0);
  		XA_BUG_ON(xa, id != 8);
  
  		xa_release(xa, 6);
  		XA_BUG_ON(xa, xa_alloc(xa, &id, xa_mk_value(6),
  					XA_LIMIT(5, 10), GFP_KERNEL) != 0);
  		XA_BUG_ON(xa, id != 6);

  	}

  	xa_destroy(xa);
  }

  static noinline void check_xas_erase(struct xarray *xa)
  {
  	XA_STATE(xas, xa, 0);
  	void *entry;
  	unsigned long i, j;
  
  	for (i = 0; i < 200; i++) {
  		for (j = i; j < 2 * i + 17; j++) {
  			xas_set(&xas, j);
  			do {
  				xas_lock(&xas);

  				xas_store(&xas, xa_mk_index(j));

  				xas_unlock(&xas);
  			} while (xas_nomem(&xas, GFP_KERNEL));
  		}
  
  		xas_set(&xas, ULONG_MAX);
  		do {
  			xas_lock(&xas);
  			xas_store(&xas, xa_mk_value(0));
  			xas_unlock(&xas);
  		} while (xas_nomem(&xas, GFP_KERNEL));
  
  		xas_lock(&xas);
  		xas_store(&xas, NULL);
  
  		xas_set(&xas, 0);
  		j = i;
  		xas_for_each(&xas, entry, ULONG_MAX) {

  			XA_BUG_ON(xa, entry != xa_mk_index(j));

  			xas_store(&xas, NULL);
  			j++;
  		}
  		xas_unlock(&xas);
  		XA_BUG_ON(xa, !xa_empty(xa));
  	}
  }

  #ifdef CONFIG_XARRAY_MULTI
  static noinline void check_multi_store_1(struct xarray *xa, unsigned long index,
  		unsigned int order)
  {
  	XA_STATE(xas, xa, index);
  	unsigned long min = index & ~((1UL << order) - 1);
  	unsigned long max = min + (1UL << order);

  	xa_store_order(xa, index, order, xa_mk_index(index), GFP_KERNEL);
  	XA_BUG_ON(xa, xa_load(xa, min) != xa_mk_index(index));
  	XA_BUG_ON(xa, xa_load(xa, max - 1) != xa_mk_index(index));

  	XA_BUG_ON(xa, xa_load(xa, max) != NULL);
  	XA_BUG_ON(xa, xa_load(xa, min - 1) != NULL);

  	xas_lock(&xas);

  	XA_BUG_ON(xa, xas_store(&xas, xa_mk_index(min)) != xa_mk_index(index));

  	xas_unlock(&xas);

  	XA_BUG_ON(xa, xa_load(xa, min) != xa_mk_index(min));
  	XA_BUG_ON(xa, xa_load(xa, max - 1) != xa_mk_index(min));

  	XA_BUG_ON(xa, xa_load(xa, max) != NULL);
  	XA_BUG_ON(xa, xa_load(xa, min - 1) != NULL);
  
  	xa_erase_index(xa, min);
  	XA_BUG_ON(xa, !xa_empty(xa));
  }
  
  static noinline void check_multi_store_2(struct xarray *xa, unsigned long index,
  		unsigned int order)
  {
  	XA_STATE(xas, xa, index);
  	xa_store_order(xa, index, order, xa_mk_value(0), GFP_KERNEL);

  	xas_lock(&xas);

  	XA_BUG_ON(xa, xas_store(&xas, xa_mk_value(1)) != xa_mk_value(0));
  	XA_BUG_ON(xa, xas.xa_index != index);
  	XA_BUG_ON(xa, xas_store(&xas, NULL) != xa_mk_value(1));

  	xas_unlock(&xas);

  	XA_BUG_ON(xa, !xa_empty(xa));
  }

  
  static noinline void check_multi_store_3(struct xarray *xa, unsigned long index,
  		unsigned int order)
  {
  	XA_STATE(xas, xa, 0);
  	void *entry;
  	int n = 0;
  
  	xa_store_order(xa, index, order, xa_mk_index(index), GFP_KERNEL);
  
  	xas_lock(&xas);
  	xas_for_each(&xas, entry, ULONG_MAX) {
  		XA_BUG_ON(xa, entry != xa_mk_index(index));
  		n++;
  	}
  	XA_BUG_ON(xa, n != 1);
  	xas_set(&xas, index + 1);
  	xas_for_each(&xas, entry, ULONG_MAX) {
  		XA_BUG_ON(xa, entry != xa_mk_index(index));
  		n++;
  	}
  	XA_BUG_ON(xa, n != 2);
  	xas_unlock(&xas);
  
  	xa_destroy(xa);
  }

  #endif

  static noinline void check_multi_store(struct xarray *xa)
  {
  #ifdef CONFIG_XARRAY_MULTI
  	unsigned long i, j, k;
  	unsigned int max_order = (sizeof(long) == 4) ? 30 : 60;
  
  	/* Loading from any position returns the same value */
  	xa_store_order(xa, 0, 1, xa_mk_value(0), GFP_KERNEL);
  	XA_BUG_ON(xa, xa_load(xa, 0) != xa_mk_value(0));
  	XA_BUG_ON(xa, xa_load(xa, 1) != xa_mk_value(0));
  	XA_BUG_ON(xa, xa_load(xa, 2) != NULL);
  	rcu_read_lock();
  	XA_BUG_ON(xa, xa_to_node(xa_head(xa))->count != 2);
  	XA_BUG_ON(xa, xa_to_node(xa_head(xa))->nr_values != 2);
  	rcu_read_unlock();
  
  	/* Storing adjacent to the value does not alter the value */
  	xa_store(xa, 3, xa, GFP_KERNEL);
  	XA_BUG_ON(xa, xa_load(xa, 0) != xa_mk_value(0));
  	XA_BUG_ON(xa, xa_load(xa, 1) != xa_mk_value(0));
  	XA_BUG_ON(xa, xa_load(xa, 2) != NULL);
  	rcu_read_lock();
  	XA_BUG_ON(xa, xa_to_node(xa_head(xa))->count != 3);
  	XA_BUG_ON(xa, xa_to_node(xa_head(xa))->nr_values != 2);
  	rcu_read_unlock();
  
  	/* Overwriting multiple indexes works */
  	xa_store_order(xa, 0, 2, xa_mk_value(1), GFP_KERNEL);
  	XA_BUG_ON(xa, xa_load(xa, 0) != xa_mk_value(1));
  	XA_BUG_ON(xa, xa_load(xa, 1) != xa_mk_value(1));
  	XA_BUG_ON(xa, xa_load(xa, 2) != xa_mk_value(1));
  	XA_BUG_ON(xa, xa_load(xa, 3) != xa_mk_value(1));
  	XA_BUG_ON(xa, xa_load(xa, 4) != NULL);
  	rcu_read_lock();
  	XA_BUG_ON(xa, xa_to_node(xa_head(xa))->count != 4);
  	XA_BUG_ON(xa, xa_to_node(xa_head(xa))->nr_values != 4);
  	rcu_read_unlock();
  
  	/* We can erase multiple values with a single store */

  	xa_store_order(xa, 0, BITS_PER_LONG - 1, NULL, GFP_KERNEL);

  	XA_BUG_ON(xa, !xa_empty(xa));
  
  	/* Even when the first slot is empty but the others aren't */
  	xa_store_index(xa, 1, GFP_KERNEL);
  	xa_store_index(xa, 2, GFP_KERNEL);
  	xa_store_order(xa, 0, 2, NULL, GFP_KERNEL);
  	XA_BUG_ON(xa, !xa_empty(xa));
  
  	for (i = 0; i < max_order; i++) {
  		for (j = 0; j < max_order; j++) {

  			xa_store_order(xa, 0, i, xa_mk_index(i), GFP_KERNEL);
  			xa_store_order(xa, 0, j, xa_mk_index(j), GFP_KERNEL);

  
  			for (k = 0; k < max_order; k++) {
  				void *entry = xa_load(xa, (1UL << k) - 1);
  				if ((i < k) && (j < k))
  					XA_BUG_ON(xa, entry != NULL);
  				else

  					XA_BUG_ON(xa, entry != xa_mk_index(j));

  			}
  
  			xa_erase(xa, 0);
  			XA_BUG_ON(xa, !xa_empty(xa));
  		}
  	}

  
  	for (i = 0; i < 20; i++) {
  		check_multi_store_1(xa, 200, i);
  		check_multi_store_1(xa, 0, i);
  		check_multi_store_1(xa, (1UL << i) + 1, i);
  	}
  	check_multi_store_2(xa, 4095, 9);

  
  	for (i = 1; i < 20; i++) {
  		check_multi_store_3(xa, 0, i);
  		check_multi_store_3(xa, 1UL << i, i);
  	}

  #endif
  }

  static noinline void check_xa_alloc_1(struct xarray *xa, unsigned int base)

  {
  	int i;
  	u32 id;

  	XA_BUG_ON(xa, !xa_empty(xa));
  	/* An empty array should assign %base to the first alloc */
  	xa_alloc_index(xa, base, GFP_KERNEL);

  
  	/* Erasing it should make the array empty again */

  	xa_erase_index(xa, base);
  	XA_BUG_ON(xa, !xa_empty(xa));
  
  	/* And it should assign %base again */
  	xa_alloc_index(xa, base, GFP_KERNEL);
  
  	/* Allocating and then erasing a lot should not lose base */
  	for (i = base + 1; i < 2 * XA_CHUNK_SIZE; i++)
  		xa_alloc_index(xa, i, GFP_KERNEL);
  	for (i = base; i < 2 * XA_CHUNK_SIZE; i++)
  		xa_erase_index(xa, i);
  	xa_alloc_index(xa, base, GFP_KERNEL);
  
  	/* Destroying the array should do the same as erasing */
  	xa_destroy(xa);

  	/* And it should assign %base again */
  	xa_alloc_index(xa, base, GFP_KERNEL);

  	/* The next assigned ID should be base+1 */
  	xa_alloc_index(xa, base + 1, GFP_KERNEL);
  	xa_erase_index(xa, base + 1);

  
  	/* Storing a value should mark it used */

  	xa_store_index(xa, base + 1, GFP_KERNEL);
  	xa_alloc_index(xa, base + 2, GFP_KERNEL);

  	/* If we then erase base, it should be free */
  	xa_erase_index(xa, base);
  	xa_alloc_index(xa, base, GFP_KERNEL);

  	xa_erase_index(xa, base + 1);
  	xa_erase_index(xa, base + 2);

  
  	for (i = 1; i < 5000; i++) {

  		xa_alloc_index(xa, base + i, GFP_KERNEL);

  	}

  	xa_destroy(xa);

  	/* Check that we fail properly at the limit of allocation */

  	XA_BUG_ON(xa, xa_alloc(xa, &id, xa_mk_index(UINT_MAX - 1),
  				XA_LIMIT(UINT_MAX - 1, UINT_MAX),

  				GFP_KERNEL) != 0);

  	XA_BUG_ON(xa, id != 0xfffffffeU);

  	XA_BUG_ON(xa, xa_alloc(xa, &id, xa_mk_index(UINT_MAX),
  				XA_LIMIT(UINT_MAX - 1, UINT_MAX),

  				GFP_KERNEL) != 0);

  	XA_BUG_ON(xa, id != 0xffffffffU);

  	id = 3;
  	XA_BUG_ON(xa, xa_alloc(xa, &id, xa_mk_index(0),
  				XA_LIMIT(UINT_MAX - 1, UINT_MAX),
  				GFP_KERNEL) != -EBUSY);
  	XA_BUG_ON(xa, id != 3);

  	xa_destroy(xa);

  	XA_BUG_ON(xa, xa_alloc(xa, &id, xa_mk_index(10), XA_LIMIT(10, 5),
  				GFP_KERNEL) != -EBUSY);

  	XA_BUG_ON(xa, xa_store_index(xa, 3, GFP_KERNEL) != 0);

  	XA_BUG_ON(xa, xa_alloc(xa, &id, xa_mk_index(10), XA_LIMIT(10, 5),
  				GFP_KERNEL) != -EBUSY);

  	xa_erase_index(xa, 3);
  	XA_BUG_ON(xa, !xa_empty(xa));
  }

  static noinline void check_xa_alloc_2(struct xarray *xa, unsigned int base)
  {
  	unsigned int i, id;
  	unsigned long index;
  	void *entry;
  
  	/* Allocate and free a NULL and check xa_empty() behaves */
  	XA_BUG_ON(xa, !xa_empty(xa));
  	XA_BUG_ON(xa, xa_alloc(xa, &id, NULL, xa_limit_32b, GFP_KERNEL) != 0);
  	XA_BUG_ON(xa, id != base);
  	XA_BUG_ON(xa, xa_empty(xa));
  	XA_BUG_ON(xa, xa_erase(xa, id) != NULL);
  	XA_BUG_ON(xa, !xa_empty(xa));
  
  	/* Ditto, but check destroy instead of erase */
  	XA_BUG_ON(xa, !xa_empty(xa));
  	XA_BUG_ON(xa, xa_alloc(xa, &id, NULL, xa_limit_32b, GFP_KERNEL) != 0);
  	XA_BUG_ON(xa, id != base);
  	XA_BUG_ON(xa, xa_empty(xa));
  	xa_destroy(xa);
  	XA_BUG_ON(xa, !xa_empty(xa));
  
  	for (i = base; i < base + 10; i++) {
  		XA_BUG_ON(xa, xa_alloc(xa, &id, NULL, xa_limit_32b,
  					GFP_KERNEL) != 0);
  		XA_BUG_ON(xa, id != i);
  	}
  
  	XA_BUG_ON(xa, xa_store(xa, 3, xa_mk_index(3), GFP_KERNEL) != NULL);
  	XA_BUG_ON(xa, xa_store(xa, 4, xa_mk_index(4), GFP_KERNEL) != NULL);
  	XA_BUG_ON(xa, xa_store(xa, 4, NULL, GFP_KERNEL) != xa_mk_index(4));
  	XA_BUG_ON(xa, xa_erase(xa, 5) != NULL);
  	XA_BUG_ON(xa, xa_alloc(xa, &id, NULL, xa_limit_32b, GFP_KERNEL) != 0);
  	XA_BUG_ON(xa, id != 5);
  
  	xa_for_each(xa, index, entry) {
  		xa_erase_index(xa, index);
  	}
  
  	for (i = base; i < base + 9; i++) {
  		XA_BUG_ON(xa, xa_erase(xa, i) != NULL);
  		XA_BUG_ON(xa, xa_empty(xa));
  	}
  	XA_BUG_ON(xa, xa_erase(xa, 8) != NULL);
  	XA_BUG_ON(xa, xa_empty(xa));
  	XA_BUG_ON(xa, xa_erase(xa, base + 9) != NULL);
  	XA_BUG_ON(xa, !xa_empty(xa));
  
  	xa_destroy(xa);
  }

  static noinline void check_xa_alloc_3(struct xarray *xa, unsigned int base)
  {
  	struct xa_limit limit = XA_LIMIT(1, 0x3fff);
  	u32 next = 0;
  	unsigned int i, id;
  	unsigned long index;
  	void *entry;
  
  	XA_BUG_ON(xa, xa_alloc_cyclic(xa, &id, xa_mk_index(1), limit,
  				&next, GFP_KERNEL) != 0);
  	XA_BUG_ON(xa, id != 1);
  
  	next = 0x3ffd;
  	XA_BUG_ON(xa, xa_alloc_cyclic(xa, &id, xa_mk_index(0x3ffd), limit,
  				&next, GFP_KERNEL) != 0);
  	XA_BUG_ON(xa, id != 0x3ffd);
  	xa_erase_index(xa, 0x3ffd);
  	xa_erase_index(xa, 1);
  	XA_BUG_ON(xa, !xa_empty(xa));
  
  	for (i = 0x3ffe; i < 0x4003; i++) {
  		if (i < 0x4000)
  			entry = xa_mk_index(i);
  		else
  			entry = xa_mk_index(i - 0x3fff);
  		XA_BUG_ON(xa, xa_alloc_cyclic(xa, &id, entry, limit,
  					&next, GFP_KERNEL) != (id == 1));
  		XA_BUG_ON(xa, xa_mk_index(id) != entry);
  	}
  
  	/* Check wrap-around is handled correctly */
  	if (base != 0)
  		xa_erase_index(xa, base);
  	xa_erase_index(xa, base + 1);
  	next = UINT_MAX;
  	XA_BUG_ON(xa, xa_alloc_cyclic(xa, &id, xa_mk_index(UINT_MAX),
  				xa_limit_32b, &next, GFP_KERNEL) != 0);
  	XA_BUG_ON(xa, id != UINT_MAX);
  	XA_BUG_ON(xa, xa_alloc_cyclic(xa, &id, xa_mk_index(base),
  				xa_limit_32b, &next, GFP_KERNEL) != 1);
  	XA_BUG_ON(xa, id != base);
  	XA_BUG_ON(xa, xa_alloc_cyclic(xa, &id, xa_mk_index(base + 1),
  				xa_limit_32b, &next, GFP_KERNEL) != 0);
  	XA_BUG_ON(xa, id != base + 1);
  
  	xa_for_each(xa, index, entry)
  		xa_erase_index(xa, index);
  
  	XA_BUG_ON(xa, !xa_empty(xa));
  }

  static DEFINE_XARRAY_ALLOC(xa0);
  static DEFINE_XARRAY_ALLOC1(xa1);
  
  static noinline void check_xa_alloc(void)
  {
  	check_xa_alloc_1(&xa0, 0);
  	check_xa_alloc_1(&xa1, 1);

  	check_xa_alloc_2(&xa0, 0);
  	check_xa_alloc_2(&xa1, 1);

  	check_xa_alloc_3(&xa0, 0);
  	check_xa_alloc_3(&xa1, 1);

  }

  static noinline void __check_store_iter(struct xarray *xa, unsigned long start,
  			unsigned int order, unsigned int present)
  {
  	XA_STATE_ORDER(xas, xa, start, order);
  	void *entry;
  	unsigned int count = 0;
  
  retry:
  	xas_lock(&xas);
  	xas_for_each_conflict(&xas, entry) {
  		XA_BUG_ON(xa, !xa_is_value(entry));

  		XA_BUG_ON(xa, entry < xa_mk_index(start));
  		XA_BUG_ON(xa, entry > xa_mk_index(start + (1UL << order) - 1));

  		count++;
  	}

  	xas_store(&xas, xa_mk_index(start));

  	xas_unlock(&xas);
  	if (xas_nomem(&xas, GFP_KERNEL)) {
  		count = 0;
  		goto retry;
  	}
  	XA_BUG_ON(xa, xas_error(&xas));
  	XA_BUG_ON(xa, count != present);

  	XA_BUG_ON(xa, xa_load(xa, start) != xa_mk_index(start));

  	XA_BUG_ON(xa, xa_load(xa, start + (1UL << order) - 1) !=

  			xa_mk_index(start));

  	xa_erase_index(xa, start);
  }
  
  static noinline void check_store_iter(struct xarray *xa)
  {
  	unsigned int i, j;
  	unsigned int max_order = IS_ENABLED(CONFIG_XARRAY_MULTI) ? 20 : 1;
  
  	for (i = 0; i < max_order; i++) {
  		unsigned int min = 1 << i;
  		unsigned int max = (2 << i) - 1;
  		__check_store_iter(xa, 0, i, 0);
  		XA_BUG_ON(xa, !xa_empty(xa));
  		__check_store_iter(xa, min, i, 0);
  		XA_BUG_ON(xa, !xa_empty(xa));
  
  		xa_store_index(xa, min, GFP_KERNEL);
  		__check_store_iter(xa, min, i, 1);
  		XA_BUG_ON(xa, !xa_empty(xa));
  		xa_store_index(xa, max, GFP_KERNEL);
  		__check_store_iter(xa, min, i, 1);
  		XA_BUG_ON(xa, !xa_empty(xa));
  
  		for (j = 0; j < min; j++)
  			xa_store_index(xa, j, GFP_KERNEL);
  		__check_store_iter(xa, 0, i, min);
  		XA_BUG_ON(xa, !xa_empty(xa));
  		for (j = 0; j < min; j++)
  			xa_store_index(xa, min + j, GFP_KERNEL);
  		__check_store_iter(xa, min, i, min);
  		XA_BUG_ON(xa, !xa_empty(xa));
  	}
  #ifdef CONFIG_XARRAY_MULTI
  	xa_store_index(xa, 63, GFP_KERNEL);
  	xa_store_index(xa, 65, GFP_KERNEL);
  	__check_store_iter(xa, 64, 2, 1);
  	xa_erase_index(xa, 63);
  #endif
  	XA_BUG_ON(xa, !xa_empty(xa));
  }

  static noinline void check_multi_find_1(struct xarray *xa, unsigned order)

  {
  #ifdef CONFIG_XARRAY_MULTI

  	unsigned long multi = 3 << order;
  	unsigned long next = 4 << order;

  	unsigned long index;

  	xa_store_order(xa, multi, order, xa_mk_value(multi), GFP_KERNEL);
  	XA_BUG_ON(xa, xa_store_index(xa, next, GFP_KERNEL) != NULL);

  	XA_BUG_ON(xa, xa_store_index(xa, next + 1, GFP_KERNEL) != NULL);

  
  	index = 0;
  	XA_BUG_ON(xa, xa_find(xa, &index, ULONG_MAX, XA_PRESENT) !=

  			xa_mk_value(multi));
  	XA_BUG_ON(xa, index != multi);
  	index = multi + 1;

  	XA_BUG_ON(xa, xa_find(xa, &index, ULONG_MAX, XA_PRESENT) !=

  			xa_mk_value(multi));
  	XA_BUG_ON(xa, (index < multi) || (index >= next));

  	XA_BUG_ON(xa, xa_find_after(xa, &index, ULONG_MAX, XA_PRESENT) !=

  			xa_mk_value(next));
  	XA_BUG_ON(xa, index != next);

  	XA_BUG_ON(xa, xa_find_after(xa, &index, next, XA_PRESENT) != NULL);
  	XA_BUG_ON(xa, index != next);

  	xa_erase_index(xa, multi);
  	xa_erase_index(xa, next);

  	xa_erase_index(xa, next + 1);

  	XA_BUG_ON(xa, !xa_empty(xa));
  #endif
  }
  
  static noinline void check_multi_find_2(struct xarray *xa)
  {
  	unsigned int max_order = IS_ENABLED(CONFIG_XARRAY_MULTI) ? 10 : 1;
  	unsigned int i, j;
  	void *entry;
  
  	for (i = 0; i < max_order; i++) {
  		unsigned long index = 1UL << i;
  		for (j = 0; j < index; j++) {
  			XA_STATE(xas, xa, j + index);
  			xa_store_index(xa, index - 1, GFP_KERNEL);

  			xa_store_order(xa, index, i, xa_mk_index(index),

  					GFP_KERNEL);
  			rcu_read_lock();
  			xas_for_each(&xas, entry, ULONG_MAX) {
  				xa_erase_index(xa, index);
  			}
  			rcu_read_unlock();
  			xa_erase_index(xa, index - 1);
  			XA_BUG_ON(xa, !xa_empty(xa));
  		}
  	}
  }

  static noinline void check_multi_find_3(struct xarray *xa)
  {
  	unsigned int order;
  
  	for (order = 5; order < order_limit; order++) {
  		unsigned long index = 1UL << (order - 5);
  
  		XA_BUG_ON(xa, !xa_empty(xa));
  		xa_store_order(xa, 0, order - 4, xa_mk_index(0), GFP_KERNEL);
  		XA_BUG_ON(xa, xa_find_after(xa, &index, ULONG_MAX, XA_PRESENT));
  		xa_erase_index(xa, 0);
  	}
  }

  static noinline void check_find_1(struct xarray *xa)

  {
  	unsigned long i, j, k;
  
  	XA_BUG_ON(xa, !xa_empty(xa));
  
  	/*
  	 * Check xa_find with all pairs between 0 and 99 inclusive,
  	 * starting at every index between 0 and 99
  	 */
  	for (i = 0; i < 100; i++) {
  		XA_BUG_ON(xa, xa_store_index(xa, i, GFP_KERNEL) != NULL);
  		xa_set_mark(xa, i, XA_MARK_0);
  		for (j = 0; j < i; j++) {
  			XA_BUG_ON(xa, xa_store_index(xa, j, GFP_KERNEL) !=
  					NULL);
  			xa_set_mark(xa, j, XA_MARK_0);
  			for (k = 0; k < 100; k++) {
  				unsigned long index = k;
  				void *entry = xa_find(xa, &index, ULONG_MAX,
  								XA_PRESENT);
  				if (k <= j)
  					XA_BUG_ON(xa, index != j);
  				else if (k <= i)
  					XA_BUG_ON(xa, index != i);
  				else
  					XA_BUG_ON(xa, entry != NULL);
  
  				index = k;
  				entry = xa_find(xa, &index, ULONG_MAX,
  								XA_MARK_0);
  				if (k <= j)
  					XA_BUG_ON(xa, index != j);
  				else if (k <= i)
  					XA_BUG_ON(xa, index != i);
  				else
  					XA_BUG_ON(xa, entry != NULL);
  			}
  			xa_erase_index(xa, j);
  			XA_BUG_ON(xa, xa_get_mark(xa, j, XA_MARK_0));
  			XA_BUG_ON(xa, !xa_get_mark(xa, i, XA_MARK_0));
  		}
  		xa_erase_index(xa, i);
  		XA_BUG_ON(xa, xa_get_mark(xa, i, XA_MARK_0));
  	}
  	XA_BUG_ON(xa, !xa_empty(xa));

  }
  
  static noinline void check_find_2(struct xarray *xa)
  {
  	void *entry;

  	unsigned long i, j, index;

  	xa_for_each(xa, index, entry) {

  		XA_BUG_ON(xa, true);
  	}
  
  	for (i = 0; i < 1024; i++) {
  		xa_store_index(xa, index, GFP_KERNEL);
  		j = 0;

  		xa_for_each(xa, index, entry) {

  			XA_BUG_ON(xa, xa_mk_index(index) != entry);

  			XA_BUG_ON(xa, index != j++);
  		}
  	}
  
  	xa_destroy(xa);
  }

  static noinline void check_find_3(struct xarray *xa)
  {
  	XA_STATE(xas, xa, 0);
  	unsigned long i, j, k;
  	void *entry;
  
  	for (i = 0; i < 100; i++) {
  		for (j = 0; j < 100; j++) {

  			rcu_read_lock();

  			for (k = 0; k < 100; k++) {
  				xas_set(&xas, j);
  				xas_for_each_marked(&xas, entry, k, XA_MARK_0)
  					;
  				if (j > k)
  					XA_BUG_ON(xa,
  						xas.xa_node != XAS_RESTART);
  			}

  			rcu_read_unlock();

  		}
  		xa_store_index(xa, i, GFP_KERNEL);
  		xa_set_mark(xa, i, XA_MARK_0);
  	}
  	xa_destroy(xa);
  }

  static noinline void check_find_4(struct xarray *xa)
  {
  	unsigned long index = 0;
  	void *entry;
  
  	xa_store_index(xa, ULONG_MAX, GFP_KERNEL);
  
  	entry = xa_find_after(xa, &index, ULONG_MAX, XA_PRESENT);
  	XA_BUG_ON(xa, entry != xa_mk_index(ULONG_MAX));
  
  	entry = xa_find_after(xa, &index, ULONG_MAX, XA_PRESENT);
  	XA_BUG_ON(xa, entry);
  
  	xa_erase_index(xa, ULONG_MAX);
  }

  static noinline void check_find(struct xarray *xa)
  {

  	unsigned i;

  	check_find_1(xa);
  	check_find_2(xa);

  	check_find_3(xa);

  	check_find_4(xa);

  
  	for (i = 2; i < 10; i++)
  		check_multi_find_1(xa, i);

  	check_multi_find_2(xa);

  	check_multi_find_3(xa);

  }

  /* See find_swap_entry() in mm/shmem.c */
  static noinline unsigned long xa_find_entry(struct xarray *xa, void *item)
  {
  	XA_STATE(xas, xa, 0);
  	unsigned int checked = 0;
  	void *entry;
  
  	rcu_read_lock();
  	xas_for_each(&xas, entry, ULONG_MAX) {
  		if (xas_retry(&xas, entry))
  			continue;
  		if (entry == item)
  			break;
  		checked++;
  		if ((checked % 4) != 0)
  			continue;
  		xas_pause(&xas);
  	}
  	rcu_read_unlock();
  
  	return entry ? xas.xa_index : -1;
  }
  
  static noinline void check_find_entry(struct xarray *xa)
  {
  #ifdef CONFIG_XARRAY_MULTI
  	unsigned int order;
  	unsigned long offset, index;
  
  	for (order = 0; order < 20; order++) {
  		for (offset = 0; offset < (1UL << (order + 3));
  		     offset += (1UL << order)) {
  			for (index = 0; index < (1UL << (order + 5));
  			     index += (1UL << order)) {
  				xa_store_order(xa, index, order,

  						xa_mk_index(index), GFP_KERNEL);

  				XA_BUG_ON(xa, xa_load(xa, index) !=

  						xa_mk_index(index));

  				XA_BUG_ON(xa, xa_find_entry(xa,

  						xa_mk_index(index)) != index);

  			}
  			XA_BUG_ON(xa, xa_find_entry(xa, xa) != -1);
  			xa_destroy(xa);
  		}
  	}
  #endif
  
  	XA_BUG_ON(xa, xa_find_entry(xa, xa) != -1);
  	xa_store_index(xa, ULONG_MAX, GFP_KERNEL);
  	XA_BUG_ON(xa, xa_find_entry(xa, xa) != -1);

  	XA_BUG_ON(xa, xa_find_entry(xa, xa_mk_index(ULONG_MAX)) != -1);

  	xa_erase_index(xa, ULONG_MAX);
  	XA_BUG_ON(xa, !xa_empty(xa));
  }

  static noinline void check_pause(struct xarray *xa)
  {
  	XA_STATE(xas, xa, 0);
  	void *entry;
  	unsigned int order;
  	unsigned long index = 1;
  	unsigned int count = 0;
  
  	for (order = 0; order < order_limit; order++) {
  		XA_BUG_ON(xa, xa_store_order(xa, index, order,
  					xa_mk_index(index), GFP_KERNEL));
  		index += 1UL << order;
  	}
  
  	rcu_read_lock();
  	xas_for_each(&xas, entry, ULONG_MAX) {
  		XA_BUG_ON(xa, entry != xa_mk_index(1UL << count));
  		count++;
  	}
  	rcu_read_unlock();
  	XA_BUG_ON(xa, count != order_limit);
  
  	count = 0;
  	xas_set(&xas, 0);
  	rcu_read_lock();
  	xas_for_each(&xas, entry, ULONG_MAX) {
  		XA_BUG_ON(xa, entry != xa_mk_index(1UL << count));
  		count++;
  		xas_pause(&xas);
  	}
  	rcu_read_unlock();
  	XA_BUG_ON(xa, count != order_limit);
  
  	xa_destroy(xa);
  }

  static noinline void check_move_tiny(struct xarray *xa)
  {
  	XA_STATE(xas, xa, 0);
  
  	XA_BUG_ON(xa, !xa_empty(xa));
  	rcu_read_lock();
  	XA_BUG_ON(xa, xas_next(&xas) != NULL);
  	XA_BUG_ON(xa, xas_next(&xas) != NULL);
  	rcu_read_unlock();
  	xa_store_index(xa, 0, GFP_KERNEL);
  	rcu_read_lock();
  	xas_set(&xas, 0);
  	XA_BUG_ON(xa, xas_next(&xas) != xa_mk_index(0));
  	XA_BUG_ON(xa, xas_next(&xas) != NULL);
  	xas_set(&xas, 0);
  	XA_BUG_ON(xa, xas_prev(&xas) != xa_mk_index(0));
  	XA_BUG_ON(xa, xas_prev(&xas) != NULL);
  	rcu_read_unlock();
  	xa_erase_index(xa, 0);
  	XA_BUG_ON(xa, !xa_empty(xa));
  }

  static noinline void check_move_max(struct xarray *xa)
  {
  	XA_STATE(xas, xa, 0);
  
  	xa_store_index(xa, ULONG_MAX, GFP_KERNEL);
  	rcu_read_lock();
  	XA_BUG_ON(xa, xas_find(&xas, ULONG_MAX) != xa_mk_index(ULONG_MAX));
  	XA_BUG_ON(xa, xas_find(&xas, ULONG_MAX) != NULL);
  	rcu_read_unlock();
  
  	xas_set(&xas, 0);
  	rcu_read_lock();
  	XA_BUG_ON(xa, xas_find(&xas, ULONG_MAX) != xa_mk_index(ULONG_MAX));
  	xas_pause(&xas);
  	XA_BUG_ON(xa, xas_find(&xas, ULONG_MAX) != NULL);
  	rcu_read_unlock();
  
  	xa_erase_index(xa, ULONG_MAX);
  	XA_BUG_ON(xa, !xa_empty(xa));
  }

  static noinline void check_move_small(struct xarray *xa, unsigned long idx)
  {
  	XA_STATE(xas, xa, 0);
  	unsigned long i;
  
  	xa_store_index(xa, 0, GFP_KERNEL);
  	xa_store_index(xa, idx, GFP_KERNEL);
  
  	rcu_read_lock();
  	for (i = 0; i < idx * 4; i++) {
  		void *entry = xas_next(&xas);
  		if (i <= idx)
  			XA_BUG_ON(xa, xas.xa_node == XAS_RESTART);
  		XA_BUG_ON(xa, xas.xa_index != i);
  		if (i == 0 || i == idx)

  			XA_BUG_ON(xa, entry != xa_mk_index(i));

  		else
  			XA_BUG_ON(xa, entry != NULL);
  	}
  	xas_next(&xas);
  	XA_BUG_ON(xa, xas.xa_index != i);
  
  	do {
  		void *entry = xas_prev(&xas);
  		i--;
  		if (i <= idx)
  			XA_BUG_ON(xa, xas.xa_node == XAS_RESTART);
  		XA_BUG_ON(xa, xas.xa_index != i);
  		if (i == 0 || i == idx)

  			XA_BUG_ON(xa, entry != xa_mk_index(i));

  		else
  			XA_BUG_ON(xa, entry != NULL);
  	} while (i > 0);
  
  	xas_set(&xas, ULONG_MAX);
  	XA_BUG_ON(xa, xas_next(&xas) != NULL);
  	XA_BUG_ON(xa, xas.xa_index != ULONG_MAX);
  	XA_BUG_ON(xa, xas_next(&xas) != xa_mk_value(0));
  	XA_BUG_ON(xa, xas.xa_index != 0);
  	XA_BUG_ON(xa, xas_prev(&xas) != NULL);
  	XA_BUG_ON(xa, xas.xa_index != ULONG_MAX);
  	rcu_read_unlock();
  
  	xa_erase_index(xa, 0);
  	xa_erase_index(xa, idx);
  	XA_BUG_ON(xa, !xa_empty(xa));
  }
  
  static noinline void check_move(struct xarray *xa)
  {
  	XA_STATE(xas, xa, (1 << 16) - 1);
  	unsigned long i;
  
  	for (i = 0; i < (1 << 16); i++)
  		XA_BUG_ON(xa, xa_store_index(xa, i, GFP_KERNEL) != NULL);
  
  	rcu_read_lock();
  	do {
  		void *entry = xas_prev(&xas);
  		i--;

  		XA_BUG_ON(xa, entry != xa_mk_index(i));

  		XA_BUG_ON(xa, i != xas.xa_index);
  	} while (i != 0);
  
  	XA_BUG_ON(xa, xas_prev(&xas) != NULL);
  	XA_BUG_ON(xa, xas.xa_index != ULONG_MAX);
  
  	do {
  		void *entry = xas_next(&xas);

  		XA_BUG_ON(xa, entry != xa_mk_index(i));

  		XA_BUG_ON(xa, i != xas.xa_index);
  		i++;
  	} while (i < (1 << 16));
  	rcu_read_unlock();
  
  	for (i = (1 << 8); i < (1 << 15); i++)
  		xa_erase_index(xa, i);
  
  	i = xas.xa_index;
  
  	rcu_read_lock();
  	do {
  		void *entry = xas_prev(&xas);
  		i--;
  		if ((i < (1 << 8)) || (i >= (1 << 15)))

  			XA_BUG_ON(xa, entry != xa_mk_index(i));

  		else
  			XA_BUG_ON(xa, entry != NULL);
  		XA_BUG_ON(xa, i != xas.xa_index);
  	} while (i != 0);
  
  	XA_BUG_ON(xa, xas_prev(&xas) != NULL);
  	XA_BUG_ON(xa, xas.xa_index != ULONG_MAX);
  
  	do {
  		void *entry = xas_next(&xas);
  		if ((i < (1 << 8)) || (i >= (1 << 15)))

  			XA_BUG_ON(xa, entry != xa_mk_index(i));

  		else
  			XA_BUG_ON(xa, entry != NULL);
  		XA_BUG_ON(xa, i != xas.xa_index);
  		i++;
  	} while (i < (1 << 16));
  	rcu_read_unlock();
  
  	xa_destroy(xa);

  	check_move_tiny(xa);

  	check_move_max(xa);

  	for (i = 0; i < 16; i++)
  		check_move_small(xa, 1UL << i);
  
  	for (i = 2; i < 16; i++)
  		check_move_small(xa, (1UL << i) - 1);
  }

  static noinline void xa_store_many_order(struct xarray *xa,
  		unsigned long index, unsigned order)
  {
  	XA_STATE_ORDER(xas, xa, index, order);
  	unsigned int i = 0;
  
  	do {
  		xas_lock(&xas);
  		XA_BUG_ON(xa, xas_find_conflict(&xas));
  		xas_create_range(&xas);
  		if (xas_error(&xas))
  			goto unlock;
  		for (i = 0; i < (1U << order); i++) {

  			XA_BUG_ON(xa, xas_store(&xas, xa_mk_index(index + i)));

  			xas_next(&xas);
  		}
  unlock:
  		xas_unlock(&xas);
  	} while (xas_nomem(&xas, GFP_KERNEL));
  
  	XA_BUG_ON(xa, xas_error(&xas));
  }
  
  static noinline void check_create_range_1(struct xarray *xa,
  		unsigned long index, unsigned order)
  {
  	unsigned long i;
  
  	xa_store_many_order(xa, index, order);
  	for (i = index; i < index + (1UL << order); i++)
  		xa_erase_index(xa, i);
  	XA_BUG_ON(xa, !xa_empty(xa));
  }
  
  static noinline void check_create_range_2(struct xarray *xa, unsigned order)
  {
  	unsigned long i;
  	unsigned long nr = 1UL << order;
  
  	for (i = 0; i < nr * nr; i += nr)
  		xa_store_many_order(xa, i, order);
  	for (i = 0; i < nr * nr; i++)
  		xa_erase_index(xa, i);
  	XA_BUG_ON(xa, !xa_empty(xa));
  }
  
  static noinline void check_create_range_3(void)
  {
  	XA_STATE(xas, NULL, 0);
  	xas_set_err(&xas, -EEXIST);
  	xas_create_range(&xas);
  	XA_BUG_ON(NULL, xas_error(&xas) != -EEXIST);
  }
  
  static noinline void check_create_range_4(struct xarray *xa,
  		unsigned long index, unsigned order)
  {
  	XA_STATE_ORDER(xas, xa, index, order);
  	unsigned long base = xas.xa_index;
  	unsigned long i = 0;
  
  	xa_store_index(xa, index, GFP_KERNEL);
  	do {
  		xas_lock(&xas);
  		xas_create_range(&xas);
  		if (xas_error(&xas))
  			goto unlock;
  		for (i = 0; i < (1UL << order); i++) {

  			void *old = xas_store(&xas, xa_mk_index(base + i));

  			if (xas.xa_index == index)

  				XA_BUG_ON(xa, old != xa_mk_index(base + i));

  			else
  				XA_BUG_ON(xa, old != NULL);
  			xas_next(&xas);
  		}
  unlock:
  		xas_unlock(&xas);
  	} while (xas_nomem(&xas, GFP_KERNEL));
  
  	XA_BUG_ON(xa, xas_error(&xas));
  
  	for (i = base; i < base + (1UL << order); i++)
  		xa_erase_index(xa, i);
  	XA_BUG_ON(xa, !xa_empty(xa));
  }
  
  static noinline void check_create_range(struct xarray *xa)
  {
  	unsigned int order;
  	unsigned int max_order = IS_ENABLED(CONFIG_XARRAY_MULTI) ? 12 : 1;
  
  	for (order = 0; order < max_order; order++) {
  		check_create_range_1(xa, 0, order);
  		check_create_range_1(xa, 1U << order, order);
  		check_create_range_1(xa, 2U << order, order);
  		check_create_range_1(xa, 3U << order, order);
  		check_create_range_1(xa, 1U << 24, order);
  		if (order < 10)
  			check_create_range_2(xa, order);
  
  		check_create_range_4(xa, 0, order);
  		check_create_range_4(xa, 1U << order, order);
  		check_create_range_4(xa, 2U << order, order);
  		check_create_range_4(xa, 3U << order, order);
  		check_create_range_4(xa, 1U << 24, order);
  
  		check_create_range_4(xa, 1, order);
  		check_create_range_4(xa, (1U << order) + 1, order);
  		check_create_range_4(xa, (2U << order) + 1, order);
  		check_create_range_4(xa, (2U << order) - 1, order);
  		check_create_range_4(xa, (3U << order) + 1, order);
  		check_create_range_4(xa, (3U << order) - 1, order);
  		check_create_range_4(xa, (1U << 24) + 1, order);
  	}
  
  	check_create_range_3();
  }

  static noinline void __check_store_range(struct xarray *xa, unsigned long first,
  		unsigned long last)
  {
  #ifdef CONFIG_XARRAY_MULTI

  	xa_store_range(xa, first, last, xa_mk_index(first), GFP_KERNEL);

  	XA_BUG_ON(xa, xa_load(xa, first) != xa_mk_index(first));
  	XA_BUG_ON(xa, xa_load(xa, last) != xa_mk_index(first));

  	XA_BUG_ON(xa, xa_load(xa, first - 1) != NULL);
  	XA_BUG_ON(xa, xa_load(xa, last + 1) != NULL);
  
  	xa_store_range(xa, first, last, NULL, GFP_KERNEL);
  #endif
  
  	XA_BUG_ON(xa, !xa_empty(xa));
  }
  
  static noinline void check_store_range(struct xarray *xa)
  {
  	unsigned long i, j;
  
  	for (i = 0; i < 128; i++) {
  		for (j = i; j < 128; j++) {
  			__check_store_range(xa, i, j);
  			__check_store_range(xa, 128 + i, 128 + j);
  			__check_store_range(xa, 4095 + i, 4095 + j);
  			__check_store_range(xa, 4096 + i, 4096 + j);
  			__check_store_range(xa, 123456 + i, 123456 + j);

  			__check_store_range(xa, (1 << 24) + i, (1 << 24) + j);

  		}
  	}
  }

  #ifdef CONFIG_XARRAY_MULTI
  static void check_split_1(struct xarray *xa, unsigned long index,
  							unsigned int order)
  {
  	XA_STATE(xas, xa, index);
  	void *entry;
  	unsigned int i = 0;
  
  	xa_store_order(xa, index, order, xa, GFP_KERNEL);
  
  	xas_split_alloc(&xas, xa, order, GFP_KERNEL);
  	xas_lock(&xas);
  	xas_split(&xas, xa, order);
  	xas_unlock(&xas);
  
  	xa_for_each(xa, index, entry) {
  		XA_BUG_ON(xa, entry != xa);
  		i++;
  	}
  	XA_BUG_ON(xa, i != 1 << order);
  
  	xa_set_mark(xa, index, XA_MARK_0);
  	XA_BUG_ON(xa, !xa_get_mark(xa, index, XA_MARK_0));
  
  	xa_destroy(xa);
  }
  
  static noinline void check_split(struct xarray *xa)
  {
  	unsigned int order;
  
  	XA_BUG_ON(xa, !xa_empty(xa));
  
  	for (order = 1; order < 2 * XA_CHUNK_SHIFT; order++) {
  		check_split_1(xa, 0, order);
  		check_split_1(xa, 1UL << order, order);
  		check_split_1(xa, 3UL << order, order);
  	}
  }
  #else
  static void check_split(struct xarray *xa) { }
  #endif

  static void check_align_1(struct xarray *xa, char *name)
  {
  	int i;
  	unsigned int id;
  	unsigned long index;
  	void *entry;
  
  	for (i = 0; i < 8; i++) {

  		XA_BUG_ON(xa, xa_alloc(xa, &id, name + i, xa_limit_32b,
  					GFP_KERNEL) != 0);

  		XA_BUG_ON(xa, id != i);
  	}
  	xa_for_each(xa, index, entry)
  		XA_BUG_ON(xa, xa_is_err(entry));
  	xa_destroy(xa);
  }

  /*
   * We should always be able to store without allocating memory after
   * reserving a slot.
   */

  static void check_align_2(struct xarray *xa, char *name)
  {
  	int i;
  
  	XA_BUG_ON(xa, !xa_empty(xa));
  
  	for (i = 0; i < 8; i++) {
  		XA_BUG_ON(xa, xa_store(xa, 0, name + i, GFP_KERNEL) != NULL);
  		xa_erase(xa, 0);
  	}

  	for (i = 0; i < 8; i++) {
  		XA_BUG_ON(xa, xa_reserve(xa, 0, GFP_KERNEL) != 0);
  		XA_BUG_ON(xa, xa_store(xa, 0, name + i, 0) != NULL);
  		xa_erase(xa, 0);
  	}

  	XA_BUG_ON(xa, !xa_empty(xa));
  }

  static noinline void check_align(struct xarray *xa)
  {
  	char name[] = "Motorola 68000";
  
  	check_align_1(xa, name);
  	check_align_1(xa, name + 1);
  	check_align_1(xa, name + 2);
  	check_align_1(xa, name + 3);

  	check_align_2(xa, name);

  }

  static LIST_HEAD(shadow_nodes);
  
  static void test_update_node(struct xa_node *node)
  {
  	if (node->count && node->count == node->nr_values) {
  		if (list_empty(&node->private_list))
  			list_add(&shadow_nodes, &node->private_list);
  	} else {
  		if (!list_empty(&node->private_list))
  			list_del_init(&node->private_list);
  	}
  }
  
  static noinline void shadow_remove(struct xarray *xa)
  {
  	struct xa_node *node;
  
  	xa_lock(xa);
  	while ((node = list_first_entry_or_null(&shadow_nodes,
  					struct xa_node, private_list))) {

  		XA_BUG_ON(xa, node->array != xa);
  		list_del_init(&node->private_list);

  		xa_delete_node(node, test_update_node);

  	}
  	xa_unlock(xa);
  }
  
  static noinline void check_workingset(struct xarray *xa, unsigned long index)
  {
  	XA_STATE(xas, xa, index);
  	xas_set_update(&xas, test_update_node);
  
  	do {
  		xas_lock(&xas);
  		xas_store(&xas, xa_mk_value(0));
  		xas_next(&xas);
  		xas_store(&xas, xa_mk_value(1));
  		xas_unlock(&xas);
  	} while (xas_nomem(&xas, GFP_KERNEL));
  
  	XA_BUG_ON(xa, list_empty(&shadow_nodes));
  
  	xas_lock(&xas);
  	xas_next(&xas);
  	xas_store(&xas, &xas);
  	XA_BUG_ON(xa, !list_empty(&shadow_nodes));
  
  	xas_store(&xas, xa_mk_value(2));
  	xas_unlock(&xas);
  	XA_BUG_ON(xa, list_empty(&shadow_nodes));
  
  	shadow_remove(xa);
  	XA_BUG_ON(xa, !list_empty(&shadow_nodes));
  	XA_BUG_ON(xa, !xa_empty(xa));
  }

  /*
   * Check that the pointer / value / sibling entries are accounted the
   * way we expect them to be.
   */
  static noinline void check_account(struct xarray *xa)
  {
  #ifdef CONFIG_XARRAY_MULTI
  	unsigned int order;
  
  	for (order = 1; order < 12; order++) {
  		XA_STATE(xas, xa, 1 << order);
  
  		xa_store_order(xa, 0, order, xa, GFP_KERNEL);

  		rcu_read_lock();

  		xas_load(&xas);
  		XA_BUG_ON(xa, xas.xa_node->count == 0);
  		XA_BUG_ON(xa, xas.xa_node->count > (1 << order));
  		XA_BUG_ON(xa, xas.xa_node->nr_values != 0);

  		rcu_read_unlock();

  		xa_store_order(xa, 1 << order, order, xa_mk_index(1UL << order),

  				GFP_KERNEL);
  		XA_BUG_ON(xa, xas.xa_node->count != xas.xa_node->nr_values * 2);
  
  		xa_erase(xa, 1 << order);
  		XA_BUG_ON(xa, xas.xa_node->nr_values != 0);
  
  		xa_erase(xa, 0);
  		XA_BUG_ON(xa, !xa_empty(xa));
  	}
  #endif
  }

  static noinline void check_get_order(struct xarray *xa)
  {
  	unsigned int max_order = IS_ENABLED(CONFIG_XARRAY_MULTI) ? 20 : 1;
  	unsigned int order;
  	unsigned long i, j;
  
  	for (i = 0; i < 3; i++)
  		XA_BUG_ON(xa, xa_get_order(xa, i) != 0);
  
  	for (order = 0; order < max_order; order++) {
  		for (i = 0; i < 10; i++) {
  			xa_store_order(xa, i << order, order,
  					xa_mk_index(i << order), GFP_KERNEL);
  			for (j = i << order; j < (i + 1) << order; j++)
  				XA_BUG_ON(xa, xa_get_order(xa, j) != order);
  			xa_erase(xa, i << order);
  		}
  	}
  }

  static noinline void check_destroy(struct xarray *xa)
  {
  	unsigned long index;
  
  	XA_BUG_ON(xa, !xa_empty(xa));
  
  	/* Destroying an empty array is a no-op */
  	xa_destroy(xa);
  	XA_BUG_ON(xa, !xa_empty(xa));
  
  	/* Destroying an array with a single entry */
  	for (index = 0; index < 1000; index++) {
  		xa_store_index(xa, index, GFP_KERNEL);
  		XA_BUG_ON(xa, xa_empty(xa));
  		xa_destroy(xa);
  		XA_BUG_ON(xa, !xa_empty(xa));
  	}
  
  	/* Destroying an array with a single entry at ULONG_MAX */
  	xa_store(xa, ULONG_MAX, xa, GFP_KERNEL);
  	XA_BUG_ON(xa, xa_empty(xa));
  	xa_destroy(xa);
  	XA_BUG_ON(xa, !xa_empty(xa));
  
  #ifdef CONFIG_XARRAY_MULTI
  	/* Destroying an array with a multi-index entry */
  	xa_store_order(xa, 1 << 11, 11, xa, GFP_KERNEL);
  	XA_BUG_ON(xa, xa_empty(xa));
  	xa_destroy(xa);
  	XA_BUG_ON(xa, !xa_empty(xa));
  #endif
  }

  static DEFINE_XARRAY(array);

  
  static int xarray_checks(void)
  {

  	check_xa_err(&array);

  	check_xas_retry(&array);

  	check_xa_load(&array);

  	check_xa_mark(&array);

  	check_xa_shrink(&array);

  	check_xas_erase(&array);

  	check_insert(&array);

  	check_cmpxchg(&array);

  	check_reserve(&array);

  	check_reserve(&xa0);

  	check_multi_store(&array);

  	check_get_order(&array);

  	check_xa_alloc();

  	check_find(&array);

  	check_find_entry(&array);

  	check_pause(&array);

  	check_account(&array);

  	check_destroy(&array);

  	check_move(&array);

  	check_create_range(&array);

  	check_store_range(&array);

  	check_store_iter(&array);

  	check_align(&xa0);

  	check_split(&array);

  	check_workingset(&array, 0);
  	check_workingset(&array, 64);
  	check_workingset(&array, 4096);

  	printk("XArray: %u of %u tests passed
  ", tests_passed, tests_run);
  	return (tests_run == tests_passed) ? 0 : -EINVAL;
  }
  
  static void xarray_exit(void)
  {
  }
  
  module_init(xarray_checks);
  module_exit(xarray_exit);
  MODULE_AUTHOR("Matthew Wilcox <willy@infradead.org>");
  MODULE_LICENSE("GPL");