[userspace-rcu.git] / rcuja / rcuja-range.c

/*
 * rcuja/rcuja-range.c
 *
 * Userspace RCU library - RCU Judy Array Range Support
 *
 * Copyright 2012-2013 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#define _LGPL_SOURCE
#include <stdint.h>
#include <errno.h>
#include <limits.h>
#include <string.h>
#include <assert.h>
#include <pthread.h>
#include <urcu/rcuja.h>
#include <urcu/compiler.h>
#include <urcu/arch.h>
#include <urcu-pointer.h>
#include <urcu/uatomic.h>
#include <urcu/rcuja-range.h>
#include <urcu-flavor.h>

#include "rcuja-internal.h"

/*
 * Discussion about order of lookup/lock vs allocated node deletion.
 *
 * - If node deletion returns before call to
 *   cds_ja_range_lookup(), the node will not be found by lookup.
 * - If node deletion is called after cds_ja_range_lock() returns a
 *   non-NULL range, the deletion will wait until the lock is released
 *   before it takes place.
 * - If node deletion call/return overlaps with the call to
 *   cds_ja_range_lookup() and return from cds_ja_range_lock(), the node
 *   may or may not be found by each of cds_ja_range_lookup() and
 *   cds_ja_range_lock().
 */

/*
 * Discussion about order of lookup/lock vs allocated node add. Assuming
 * no concurrent delete.
 *
 * - If node add returns before call to
 *   cds_ja_range_lookup(), the node will be found by lookup.
 * - If node add is called after cds_ja_range_lookup returns, the node
 *   will not be found by lookup.
 * - If node add call/return overlaps with the call to and return from
 *   cds_ja_range_lookup(), the node may or may not be found.
 * - If node add call/return overlaps with call to cds_ja_range_lookup()
 *   and return from cds_ja_range_lock(), in the specific case where
 *   cds_ja_range_lookup() _does_ succeed, then cds_ja_range_lock() will
 *   succeed (still assuming no concurrent deletion).
 */

/*
 * Discussion: concurrent deletion of contiguous allocated ranges.
 *
 * Ensuring that merge of contiguous free ranges is always performed, we
 * need to ensure locking of concurrent removal of contiguous allocated
 * ranges one with respect to another. This is done by locking the
 * ranges prior to and after the range to remove, even if that range is
 * allocated. This serializes removal of contiguous ranges. The only
 * cases for which there is no range to lock is when removing an
 * allocated range starting at 0, and/or ending at the end of the key
 * space.
 */

/*
 * Discussion of the type state transitions.
 *
 * State transitions of "type" always go from either:
 *
 * CDS_JA_RANGE_FREE -> CDS_JA_RANGE_REMOVED
 * or
 * CDS_JA_RANGE_ALLOCATED -> CDS_JA_RANGE_REMOVED
 *
 * A range type never changes otherwise.
 */


struct cds_ja_range *cds_ja_range_lookup(struct cds_ja *ja, uint64_t key)
{
	struct cds_ja_node *node, *last_node;
	struct cds_ja_range *range;

	node = cds_ja_lookup_below_equal(ja, key, NULL);
	assert(node);
	/*
	 * Get the last of duplicate chain. Adding a node to Judy array
	 * duplicates inserts them at the end of the chain.
	 */
	cds_ja_for_each_duplicate_rcu(node)
		last_node = node;
	range = caa_container_of(last_node, struct cds_ja_range, ja_node);
	/*
	 * If last node in the duplicates is removed or free, we can
	 * consider that either a removal or add operation is in
	 * progress, or removal is the last completed operation to
	 * update this range. We can therefore consider that this area
	 * is not allocated.
	 */
	if (range->type != CDS_JA_RANGE_ALLOCATED)
		return NULL;
	/*
	 * We found an allocated range. We can return it for use with
	 * RCU read-side protection for existence. However, we have no
	 * mutual exclusion against removal at this point.
	 */
	return range;
}

/*
 * Provide mutual exclusion against removal.
 */
struct cds_ja_range *cds_ja_range_lock(struct cds_ja_range *range)
{
	pthread_mutex_lock(&range->lock);

	if (range->type == CDS_JA_RANGE_REMOVED)
		goto removed;
	return range;

removed:
	pthread_mutex_unlock(&range->lock);
	return NULL;
}

void cds_ja_range_unlock(struct cds_ja_range *range)
{
	pthread_mutex_unlock(&range->lock);
}

static
struct cds_ja_range *range_create(
		uint64_t start,		/* inclusive */
		uint64_t end,		/* inclusive */
		enum cds_ja_range_type type)
{
	struct cds_ja_range *range;

	range = calloc(sizeof(*range), 1);
	if (!range)
		return NULL;
	range->start = start;
	range->end = end;
	range->type = type;
	pthread_mutex_init(&range->lock, NULL);
	return range;
}

static
void free_range_cb(struct rcu_head *head)
{
	struct cds_ja_range *range =
		caa_container_of(head, struct cds_ja_range, head);
	free(range);
}

static
void free_range(struct cds_ja_range *range)
{
	free(range);
}

static
void rcu_free_range(struct cds_ja *ja, struct cds_ja_range *range)
{
	cds_lfht_rcu_flavor(ja->ht)->update_call_rcu(&range->head,
			free_range_cb);
}

struct cds_ja_range *cds_ja_range_add(struct cds_ja *ja,
		uint64_t start,		/* inclusive */
		uint64_t end)		/* inclusive */
{
	struct cds_ja_node *old_node, *old_node_end;
	struct cds_ja_range *old_range, *old_range_end, *new_range, *ranges[3];
	unsigned int nr_ranges, i;
	int ret;

retry:
	/*
	 * Find if requested range is entirely contained within a single
	 * free range.
	 */
	old_node = cds_ja_lookup_below_equal(ja, start, NULL);
	assert(old_node);

	old_range = caa_container_of(old_node, struct cds_ja_range, ja_node);
	switch (CMM_LOAD_SHARED(old_range->type)) {
	case CDS_JA_RANGE_ALLOCATED:
		return NULL;
	case CDS_JA_RANGE_FREE:
		break;
	case CDS_JA_RANGE_REMOVED:
		goto retry;
	}

	old_node_end = cds_ja_lookup_below_equal(ja, end, NULL);
	assert(old_node_end);
	old_range_end = caa_container_of(old_node_end,
			struct cds_ja_range, ja_node);
	if (old_range_end != old_range) {
		switch (CMM_LOAD_SHARED(old_range->type)) {
		case CDS_JA_RANGE_ALLOCATED:
		case CDS_JA_RANGE_FREE:		/* fall-through */
			return NULL;
		case CDS_JA_RANGE_REMOVED:
			goto retry;
		}
	}

	pthread_mutex_lock(&old_range->lock);

	if (old_range->type == CDS_JA_RANGE_REMOVED) {
		pthread_mutex_unlock(&old_range->lock);
		goto retry;
	}

	/* Create replacement ranges: at most 2 free and 1 allocated */
	if (start == old_range->start) {
		if (end == old_range->end) {
			/* 1 range */
			ranges[0] = new_range = range_create(start, end,
				CDS_JA_RANGE_ALLOCATED);
			nr_ranges = 1;
		} else {
			/* 2 ranges */
			ranges[0] = new_range = range_create(start, end,
				CDS_JA_RANGE_ALLOCATED);
			ranges[1] = range_create(end + 1, old_range->end,
				CDS_JA_RANGE_FREE);
			nr_ranges = 2;
		}
	} else {
		if (end == old_range->end) {
			/* 2 ranges */
			ranges[0] = range_create(old_range->start, start - 1,
				CDS_JA_RANGE_FREE);
			ranges[1] = new_range = range_create(start, end,
				CDS_JA_RANGE_ALLOCATED);
			nr_ranges = 2;
		} else {
			/* 3 ranges */
			ranges[0] = range_create(old_range->start, start - 1,
				CDS_JA_RANGE_FREE);
			ranges[1] = new_range = range_create(start, end,
				CDS_JA_RANGE_ALLOCATED);
			ranges[2] = range_create(end + 1, old_range->end,
				CDS_JA_RANGE_FREE);
			nr_ranges = 3;
		}
	}

	/* Add replacement ranges to Judy array */
	for (i = 0; i < nr_ranges; i++) {
		ret = cds_ja_add(ja, ranges[i]->start, &ranges[i]->ja_node);
		assert(!ret);
	}

	/*
	 * We add replacement ranges _before_ removing old ranges, so
	 * concurrent traversals will always see one or the other. This
	 * is OK because we temporarily have a duplicate key, and Judy
	 * arrays provide key existence guarantee for lookups performed
	 * concurrently with add followed by del of duplicate keys.
	 */

	/* Remove old free range */
	ret = cds_ja_del(ja, old_range->start, &old_range->ja_node);
	assert(!ret);
	old_range->type = CDS_JA_RANGE_REMOVED;
	pthread_mutex_unlock(&old_range->lock);

	rcu_free_range(ja, old_range);

	return new_range;
}

int cds_ja_range_del(struct cds_ja *ja, struct cds_ja_range *range)
{
	struct cds_ja_node *prev_node, *next_node;
	struct cds_ja_range *new_range;
	struct cds_ja_range *merge_ranges[3], *lock_ranges[3];
	unsigned int nr_merge, nr_lock, i;
	uint64_t start, end;
	int ret;

retry:
	nr_merge = 0;
	nr_lock = 0;
	prev_node = cds_ja_lookup_below_equal(ja, range->start - 1, NULL);
	if (prev_node) {
		struct cds_ja_range *prev_range;

		prev_range = caa_container_of(prev_node,
			struct cds_ja_range, ja_node);
		lock_ranges[nr_lock++] = prev_range;
		if (prev_range->type != CDS_JA_RANGE_ALLOCATED)
			merge_ranges[nr_merge++] = prev_range;
	}

	lock_ranges[nr_lock++] = range;
	merge_ranges[nr_merge++] = range;

	next_node = cds_ja_lookup_above_equal(ja, range->end + 1, NULL);
	if (next_node) {
		struct cds_ja_range *next_range;

		next_range = caa_container_of(next_node,
			struct cds_ja_range, ja_node);
		lock_ranges[nr_lock++] = next_range;
		if (next_range->type != CDS_JA_RANGE_ALLOCATED)
			merge_ranges[nr_merge++] = next_range;
	}

	/* Acquire locks in increasing key order for range merge */
	for (i = 0; i < nr_lock; i++)
		pthread_mutex_lock(&lock_ranges[i]->lock);
	/* Ensure they are valid */
	for (i = 0; i < nr_lock; i++) {
		if (lock_ranges[i]->type == CDS_JA_RANGE_REMOVED)
			goto unlock_retry;
	}

	/* Create new free range */
	start = merge_ranges[0]->start;
	end = merge_ranges[nr_merge - 1]->end;
	new_range = range_create(start, end, CDS_JA_RANGE_FREE);
	ret = cds_ja_add(ja, start, &new_range->ja_node);
	assert(!ret);

	/* Remove old ranges */
	for (i = 0; i < nr_merge; i++) {
		ret = cds_ja_del(ja, merge_ranges[i]->start,
				&merge_ranges[i]->ja_node);
		assert(!ret);
		merge_ranges[i]->type = CDS_JA_RANGE_REMOVED;
	}
	for (i = 0; i < nr_lock; i++)
		pthread_mutex_unlock(&lock_ranges[i]->lock);
	/* Free old merged ranges */
	for (i = 0; i < nr_merge; i++)
		rcu_free_range(ja, merge_ranges[i]);

	return 0;

	/* retry paths */
unlock_retry:
	for (i = 0; i < nr_lock; i++)
		pthread_mutex_unlock(&lock_ranges[i]->lock);
	goto retry;
}

int cds_ja_range_init(struct cds_ja *ja)
{
	struct cds_ja_node *node;
	struct cds_ja_range *range;
	int ret;

	/*
	 * Sanity check: should be empty.
	 */
	node = cds_ja_lookup_above_equal(ja, 0, NULL);
	if (node)
		return -EINVAL;
	range = range_create(0, UINT64_MAX, CDS_JA_RANGE_FREE);
	if (!range)
		return -EINVAL;
	ret = cds_ja_add(ja, 0, &range->ja_node);
	return ret;
}

int cds_ja_range_fini(struct cds_ja *ja)
{
	uint64_t key;
	struct cds_ja_node *ja_node;
	int ret = 0;

	cds_ja_for_each_key_rcu(ja, key, ja_node) {
		struct cds_ja_node *tmp_node;

		cds_ja_for_each_duplicate_safe_rcu(ja_node, tmp_node) {
			struct cds_ja_range *range;

			range = caa_container_of(ja_node,
					struct cds_ja_range, ja_node);
			ret = cds_ja_del(ja, key, &range->ja_node);
			if (ret) {
				goto end;
			}
			/* Alone using Judy array, OK to free now */
			free_range(range);
		}
	}
end:
	return ret;
}
Commit	Line	Data
b45a45b9 MD	1	/*
	2	* rcuja/rcuja-range.c
	3	*
	4	* Userspace RCU library - RCU Judy Array Range Support
	5	*
	6	* Copyright 2012-2013 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
	7	*
	8	* This library is free software; you can redistribute it and/or
	9	* modify it under the terms of the GNU Lesser General Public
	10	* License as published by the Free Software Foundation; either
	11	* version 2.1 of the License, or (at your option) any later version.
	12	*
	13	* This library is distributed in the hope that it will be useful,
	14	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	15	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	16	* Lesser General Public License for more details.
	17	*
	18	* You should have received a copy of the GNU Lesser General Public
	19	* License along with this library; if not, write to the Free Software
	20	* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
	21	*/
	22
	23	#define _LGPL_SOURCE
	24	#include <stdint.h>
	25	#include <errno.h>
	26	#include <limits.h>
	27	#include <string.h>
	28	#include <assert.h>
	29	#include <pthread.h>
	30	#include <urcu/rcuja.h>
	31	#include <urcu/compiler.h>
	32	#include <urcu/arch.h>
	33	#include <urcu-pointer.h>
	34	#include <urcu/uatomic.h>
	35	#include <urcu/rcuja-range.h>
	36	#include <urcu-flavor.h>
	37
	38	#include "rcuja-internal.h"
	39
	40	/*
	41	* Discussion about order of lookup/lock vs allocated node deletion.
	42	*
	43	* - If node deletion returns before call to
	44	* cds_ja_range_lookup(), the node will not be found by lookup.
	45	* - If node deletion is called after cds_ja_range_lock() returns a
	46	* non-NULL range, the deletion will wait until the lock is released
	47	* before it takes place.
	48	* - If node deletion call/return overlaps with the call to
	49	* cds_ja_range_lookup() and return from cds_ja_range_lock(), the node
	50	* may or may not be found by each of cds_ja_range_lookup() and
	51	* cds_ja_range_lock().
	52	*/
	53
	54	/*
	55	* Discussion about order of lookup/lock vs allocated node add. Assuming
	56	* no concurrent delete.
	57	*
	58	* - If node add returns before call to
	59	* cds_ja_range_lookup(), the node will be found by lookup.
	60	* - If node add is called after cds_ja_range_lookup returns, the node
	61	* will not be found by lookup.
	62	* - If node add call/return overlaps with the call to and return from
	63	* cds_ja_range_lookup(), the node may or may not be found.
	64	* - If node add call/return overlaps with call to cds_ja_range_lookup()
65	* and return from cds_ja_range_lock(), in the specific case where
66	* cds_ja_range_lookup() _does_ succeed, then cds_ja_range_lock() will
67	* succeed (still assuming no concurrent deletion).
68	*/
69
c34bfad2 MD	70	/*
	71	* Discussion: concurrent deletion of contiguous allocated ranges.
	72	*
	73	* Ensuring that merge of contiguous free ranges is always performed, we
	74	* need to ensure locking of concurrent removal of contiguous allocated
	75	* ranges one with respect to another. This is done by locking the
	76	* ranges prior to and after the range to remove, even if that range is
	77	* allocated. This serializes removal of contiguous ranges. The only
	78	* cases for which there is no range to lock is when removing an
	79	* allocated range starting at 0, and/or ending at the end of the key
	80	* space.
	81	*/
	82
b45a45b9 MD	83	/*
	84	* Discussion of the type state transitions.
	85	*
	86	* State transitions of "type" always go from either:
	87	*
	88	* CDS_JA_RANGE_FREE -> CDS_JA_RANGE_REMOVED
	89	* or
	90	* CDS_JA_RANGE_ALLOCATED -> CDS_JA_RANGE_REMOVED
	91	*
	92	* A range type never changes otherwise.
	93	*/
	94
	95
	96	struct cds_ja_range cds_ja_range_lookup(struct cds_ja ja, uint64_t key)
	97	{
	98	struct cds_ja_node node, last_node;
	99	struct cds_ja_range *range;
	100
	101	node = cds_ja_lookup_below_equal(ja, key, NULL);
	102	assert(node);
	103	/*
	104	* Get the last of duplicate chain. Adding a node to Judy array
	105	* duplicates inserts them at the end of the chain.
	106	*/
	107	cds_ja_for_each_duplicate_rcu(node)
	108	last_node = node;
	109	range = caa_container_of(last_node, struct cds_ja_range, ja_node);
	110	/*
	111	* If last node in the duplicates is removed or free, we can
	112	* consider that either a removal or add operation is in
	113	* progress, or removal is the last completed operation to
	114	* update this range. We can therefore consider that this area
	115	* is not allocated.
	116	*/
	117	if (range->type != CDS_JA_RANGE_ALLOCATED)
	118	return NULL;
	119	/*
	120	* We found an allocated range. We can return it for use with
7c74dcc7	121	* RCU read-side protection for existence. However, we have no
b45a45b9 MD	122	* mutual exclusion against removal at this point.
	123	*/
	124	return range;
	125	}
	126
	127	/*
	128	* Provide mutual exclusion against removal.
	129	*/
	130	struct cds_ja_range cds_ja_range_lock(struct cds_ja_range range)
	131	{
	132	pthread_mutex_lock(&range->lock);
	133
	134	if (range->type == CDS_JA_RANGE_REMOVED)
	135	goto removed;
	136	return range;
	137
	138	removed:
	139	pthread_mutex_unlock(&range->lock);
	140	return NULL;
	141	}
	142
	143	void cds_ja_range_unlock(struct cds_ja_range *range)
	144	{
	145	pthread_mutex_unlock(&range->lock);
	146	}
	147
	148	static
	149	struct cds_ja_range *range_create(
	150	uint64_t start, /* inclusive */
	151	uint64_t end, /* inclusive */
	152	enum cds_ja_range_type type)
	153	{
	154	struct cds_ja_range *range;
	155
	156	range = calloc(sizeof(*range), 1);
	157	if (!range)
	158	return NULL;
	159	range->start = start;
	160	range->end = end;
	161	range->type = type;
	162	pthread_mutex_init(&range->lock, NULL);
	163	return range;
	164	}
	165
	166	static
	167	void free_range_cb(struct rcu_head *head)
	168	{
	169	struct cds_ja_range *range =
	170	caa_container_of(head, struct cds_ja_range, head);
	171	free(range);
	172	}
	173
	174	static
	175	void free_range(struct cds_ja_range *range)
	176	{
	177	free(range);
	178	}
	179
	180	static
	181	void rcu_free_range(struct cds_ja ja, struct cds_ja_range range)
	182	{
	183	cds_lfht_rcu_flavor(ja->ht)->update_call_rcu(&range->head,
	184	free_range_cb);
	185	}
186
187	struct cds_ja_range cds_ja_range_add(struct cds_ja ja,
188	uint64_t start, /* inclusive */
189	uint64_t end) /* inclusive */
190	{
191	struct cds_ja_node old_node, old_node_end;
192	struct cds_ja_range old_range, old_range_end, new_range, ranges[3];
193	unsigned int nr_ranges, i;
194	int ret;
195
196	retry:
197	/*
198	* Find if requested range is entirely contained within a single
199	* free range.
200	*/
201	old_node = cds_ja_lookup_below_equal(ja, start, NULL);
202	assert(old_node);
203
204	old_range = caa_container_of(old_node, struct cds_ja_range, ja_node);
205	switch (CMM_LOAD_SHARED(old_range->type)) {
206	case CDS_JA_RANGE_ALLOCATED:
207	return NULL;
208	case CDS_JA_RANGE_FREE:
209	break;
210	case CDS_JA_RANGE_REMOVED:
211	goto retry;
212	}
213
214	old_node_end = cds_ja_lookup_below_equal(ja, end, NULL);
215	assert(old_node_end);
216	old_range_end = caa_container_of(old_node_end,
217	struct cds_ja_range, ja_node);
218	if (old_range_end != old_range) {
219	switch (CMM_LOAD_SHARED(old_range->type)) {
220	case CDS_JA_RANGE_ALLOCATED:
221	case CDS_JA_RANGE_FREE: /* fall-through */
b45a45b9 MD	222	return NULL;
	223	case CDS_JA_RANGE_REMOVED:
	224	goto retry;
	225	}
	226	}
	227
	228	pthread_mutex_lock(&old_range->lock);
	229
	230	if (old_range->type == CDS_JA_RANGE_REMOVED) {
	231	pthread_mutex_unlock(&old_range->lock);
	232	goto retry;
	233	}
	234
	235	/* Create replacement ranges: at most 2 free and 1 allocated */
	236	if (start == old_range->start) {
	237	if (end == old_range->end) {
	238	/* 1 range */
	239	ranges[0] = new_range = range_create(start, end,
	240	CDS_JA_RANGE_ALLOCATED);
	241	nr_ranges = 1;
	242	} else {
	243	/* 2 ranges */
	244	ranges[0] = new_range = range_create(start, end,
	245	CDS_JA_RANGE_ALLOCATED);
	246	ranges[1] = range_create(end + 1, old_range->end,
	247	CDS_JA_RANGE_FREE);
	248	nr_ranges = 2;
	249	}
	250	} else {
	251	if (end == old_range->end) {
	252	/* 2 ranges */
	253	ranges[0] = range_create(old_range->start, start - 1,
	254	CDS_JA_RANGE_FREE);
	255	ranges[1] = new_range = range_create(start, end,
	256	CDS_JA_RANGE_ALLOCATED);
	257	nr_ranges = 2;
	258	} else {
	259	/* 3 ranges */
	260	ranges[0] = range_create(old_range->start, start - 1,
	261	CDS_JA_RANGE_FREE);
	262	ranges[1] = new_range = range_create(start, end,
	263	CDS_JA_RANGE_ALLOCATED);
	264	ranges[2] = range_create(end + 1, old_range->end,
	265	CDS_JA_RANGE_FREE);
	266	nr_ranges = 3;
	267	}
	268	}
	269
	270	/* Add replacement ranges to Judy array */
	271	for (i = 0; i < nr_ranges; i++) {
	272	ret = cds_ja_add(ja, ranges[i]->start, &ranges[i]->ja_node);
	273	assert(!ret);
	274	}
	275
	276	/*
	277	* We add replacement ranges _before_ removing old ranges, so
	278	* concurrent traversals will always see one or the other. This
	279	* is OK because we temporarily have a duplicate key, and Judy
	280	* arrays provide key existence guarantee for lookups performed
	281	* concurrently with add followed by del of duplicate keys.
	282	*/
	283
	284	/* Remove old free range */
	285	ret = cds_ja_del(ja, old_range->start, &old_range->ja_node);
286	assert(!ret);
287	old_range->type = CDS_JA_RANGE_REMOVED;
288	pthread_mutex_unlock(&old_range->lock);
289
290	rcu_free_range(ja, old_range);
291
292	return new_range;
293	}
294
295	int cds_ja_range_del(struct cds_ja ja, struct cds_ja_range range)
296	{
297	struct cds_ja_node prev_node, next_node;
c34bfad2 MD	298	struct cds_ja_range *new_range;
	299	struct cds_ja_range merge_ranges[3], lock_ranges[3];
	300	unsigned int nr_merge, nr_lock, i;
b45a45b9 MD	301	uint64_t start, end;
	302	int ret;
	303
	304	retry:
	305	nr_merge = 0;
c34bfad2	306	nr_lock = 0;
b45a45b9	307	prev_node = cds_ja_lookup_below_equal(ja, range->start - 1, NULL);
c34bfad2 MD	308	if (prev_node) {
c34bfad2 MD	309	struct cds_ja_range *prev_range;
b45a45b9	310
c34bfad2 MD	311	prev_range = caa_container_of(prev_node,
	312	struct cds_ja_range, ja_node);
	313	lock_ranges[nr_lock++] = prev_range;
	314	if (prev_range->type != CDS_JA_RANGE_ALLOCATED)
	315	merge_ranges[nr_merge++] = prev_range;
	316	}
	317
	318	lock_ranges[nr_lock++] = range;
b45a45b9 MD	319	merge_ranges[nr_merge++] = range;
	320
	321	next_node = cds_ja_lookup_above_equal(ja, range->end + 1, NULL);
c34bfad2 MD	322	if (next_node) {
	323	struct cds_ja_range *next_range;
	324
	325	next_range = caa_container_of(next_node,
	326	struct cds_ja_range, ja_node);
	327	lock_ranges[nr_lock++] = next_range;
	328	if (next_range->type != CDS_JA_RANGE_ALLOCATED)
	329	merge_ranges[nr_merge++] = next_range;
	330	}
b45a45b9 MD	331
b45a45b9 MD	332	/* Acquire locks in increasing key order for range merge */
c34bfad2 MD	333	for (i = 0; i < nr_lock; i++)
c34bfad2 MD	334	pthread_mutex_lock(&lock_ranges[i]->lock);
b45a45b9	335	/* Ensure they are valid */
c34bfad2 MD	336	for (i = 0; i < nr_lock; i++) {
c34bfad2 MD	337	if (lock_ranges[i]->type == CDS_JA_RANGE_REMOVED)
b45a45b9 MD	338	goto unlock_retry;
	339	}
	340
	341	/* Create new free range */
	342	start = merge_ranges[0]->start;
	343	end = merge_ranges[nr_merge - 1]->end;
	344	new_range = range_create(start, end, CDS_JA_RANGE_FREE);
	345	ret = cds_ja_add(ja, start, &new_range->ja_node);
	346	assert(!ret);
	347
	348	/* Remove old ranges */
	349	for (i = 0; i < nr_merge; i++) {
	350	ret = cds_ja_del(ja, merge_ranges[i]->start,
	351	&merge_ranges[i]->ja_node);
	352	assert(!ret);
	353	merge_ranges[i]->type = CDS_JA_RANGE_REMOVED;
b45a45b9	354	}
c34bfad2 MD	355	for (i = 0; i < nr_lock; i++)
	356	pthread_mutex_unlock(&lock_ranges[i]->lock);
	357	/* Free old merged ranges */
	358	for (i = 0; i < nr_merge; i++)
	359	rcu_free_range(ja, merge_ranges[i]);
b45a45b9 MD	360
	361	return 0;
	362
	363	/* retry paths */
	364	unlock_retry:
c34bfad2 MD	365	for (i = 0; i < nr_lock; i++)
c34bfad2 MD	366	pthread_mutex_unlock(&lock_ranges[i]->lock);
b45a45b9 MD	367	goto retry;
	368	}
	369
	370	int cds_ja_range_init(struct cds_ja *ja)
	371	{
	372	struct cds_ja_node *node;
	373	struct cds_ja_range *range;
	374	int ret;
	375
	376	/*
	377	* Sanity check: should be empty.
	378	*/
	379	node = cds_ja_lookup_above_equal(ja, 0, NULL);
	380	if (node)
	381	return -EINVAL;
	382	range = range_create(0, UINT64_MAX, CDS_JA_RANGE_FREE);
	383	if (!range)
	384	return -EINVAL;
	385	ret = cds_ja_add(ja, 0, &range->ja_node);
	386	return ret;
	387	}
	388
	389	int cds_ja_range_fini(struct cds_ja *ja)
	390	{
	391	uint64_t key;
	392	struct cds_ja_node *ja_node;
	393	int ret = 0;
	394
	395	cds_ja_for_each_key_rcu(ja, key, ja_node) {
	396	struct cds_ja_node *tmp_node;
	397
	398	cds_ja_for_each_duplicate_safe_rcu(ja_node, tmp_node) {
	399	struct cds_ja_range *range;
	400
	401	range = caa_container_of(ja_node,
	402	struct cds_ja_range, ja_node);
	403	ret = cds_ja_del(ja, key, &range->ja_node);
	404	if (ret) {
	405	goto end;
	406	}
	407	/* Alone using Judy array, OK to free now */
	408	free_range(range);
	409	}
	410	}
	411	end:
	412	return ret;
	413	}