numam-dpdk/lib/librte_lpm/rte_lpm.c

/*-
 *   BSD LICENSE
 * 
 *   Copyright(c) 2010-2012 Intel Corporation. All rights reserved.
 *   All rights reserved.
 * 
 *   Redistribution and use in source and binary forms, with or without 
 *   modification, are permitted provided that the following conditions 
 *   are met:
 * 
 *     * Redistributions of source code must retain the above copyright 
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright 
 *       notice, this list of conditions and the following disclaimer in 
 *       the documentation and/or other materials provided with the 
 *       distribution.
 *     * Neither the name of Intel Corporation nor the names of its 
 *       contributors may be used to endorse or promote products derived 
 *       from this software without specific prior written permission.
 * 
 *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 
 *   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 
 *   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 
 *   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 
 *   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 
 *   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 
 *   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 
 *   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 
 *   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 
 *   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 
 *   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 * 
 */

#include <string.h>
#include <stdint.h>
#include <errno.h>
#include <stdarg.h>
#include <stdio.h>
#include <errno.h>
#include <sys/queue.h>

#include <rte_log.h>
#include <rte_branch_prediction.h>
#include <rte_common.h>
#include <rte_memory.h>        /* for definition of CACHE_LINE_SIZE */
#include <rte_malloc.h>
#include <rte_memzone.h>
#include <rte_tailq.h>
#include <rte_eal.h>
#include <rte_eal_memconfig.h>
#include <rte_per_lcore.h>
#include <rte_string_fns.h>
#include <rte_errno.h>

#include "rte_lpm.h"

TAILQ_HEAD(rte_lpm_list, rte_lpm);
 
#define MAX_DEPTH_TBL24 24

enum valid_flag {
	INVALID = 0,
	VALID
};

/* Macro to enable/disable run-time checks. */
#if defined(RTE_LIBRTE_LPM_DEBUG)
#include <rte_debug.h>
#define VERIFY_DEPTH(depth) do {                                \
	if ((depth == 0) || (depth > RTE_LPM_MAX_DEPTH))        \
		rte_panic("LPM: Invalid depth (%u) at line %d", \
				(unsigned)(depth), __LINE__);   \
} while (0)
#else
#define VERIFY_DEPTH(depth)
#endif

/*
 * Converts a given depth value to its corresponding mask value.
 *
 * depth  (IN)		: range = 1 - 32
 * mask   (OUT)		: 32bit mask
 */
static uint32_t __attribute__((pure))
depth_to_mask(uint8_t depth)
{
	VERIFY_DEPTH(depth);

	/* To calculate a mask start with a 1 on the left hand side and right
	 * shift while populating the left hand side with 1's
	 */
	return (int)0x80000000 >> (depth - 1);
}

/*
 * Converts given depth value to its corresponding range value.
 */
static inline uint32_t __attribute__((pure))
depth_to_range(uint8_t depth)
{
	VERIFY_DEPTH(depth);

	/*
	 * Calculate tbl24 range. (Note: 2^depth = 1 << depth)
	 */
	if (depth <= MAX_DEPTH_TBL24)
		return 1 << (MAX_DEPTH_TBL24 - depth);

	/* Else if depth is greater than 24 */
	return (1 << (RTE_LPM_MAX_DEPTH - depth));
}

/*
 * Find an existing lpm table and return a pointer to it.
 */
struct rte_lpm *
rte_lpm_find_existing(const char *name)
{
	struct rte_lpm *l;
	struct rte_lpm_list *lpm_list;

	/* check that we have an initialised tail queue */
	if ((lpm_list = RTE_TAILQ_LOOKUP_BY_IDX(RTE_TAILQ_LPM, rte_lpm_list)) == NULL) {
		rte_errno = E_RTE_NO_TAILQ;
		return NULL;
	}

	TAILQ_FOREACH(l, lpm_list, next) {
		if (strncmp(name, l->name, RTE_LPM_NAMESIZE) == 0)
			break;
	}

	if (l == NULL)
		rte_errno = ENOENT;

	return l;
}

/*
 * Allocates memory for LPM object
 */
struct rte_lpm *
rte_lpm_create(const char *name, int socket_id, int max_rules,
		__rte_unused int flags)
{
	char mem_name[RTE_LPM_NAMESIZE];
	struct rte_lpm *lpm = NULL;
	uint32_t mem_size;
	struct rte_lpm_list *lpm_list;

	/* check that we have an initialised tail queue */
	if ((lpm_list = 
	     RTE_TAILQ_LOOKUP_BY_IDX(RTE_TAILQ_LPM, rte_lpm_list)) == NULL) {
		rte_errno = E_RTE_NO_TAILQ;
		return NULL;	
	}

	RTE_BUILD_BUG_ON(sizeof(struct rte_lpm_tbl24_entry) != 2);
	RTE_BUILD_BUG_ON(sizeof(struct rte_lpm_tbl8_entry) != 2);

	/* Check user arguments. */
	if ((name == NULL) || (socket_id < -1) || (max_rules == 0)){
		rte_errno = EINVAL;
		return NULL;
	}

	rte_snprintf(mem_name, sizeof(mem_name), "LPM_%s", name);

	/*
	 * Pad out max_rules so that each depth is given the same number of
	 * rules.
	 */
	if (max_rules % RTE_LPM_MAX_DEPTH) {
		max_rules += RTE_LPM_MAX_DEPTH -
				(max_rules % RTE_LPM_MAX_DEPTH);
	}

	/* Determine the amount of memory to allocate. */
	mem_size = sizeof(*lpm) + (sizeof(lpm->rules_tbl[0]) * max_rules);

	/* guarantee there's no existing */
	TAILQ_FOREACH(lpm, lpm_list, next) {
		if (strncmp(name, lpm->name, RTE_LPM_NAMESIZE) == 0)
			break;
	}
	if (lpm != NULL)
		return NULL;

	/* Allocate memory to store the LPM data structures. */
	lpm = (struct rte_lpm *)rte_zmalloc_socket(mem_name, mem_size,
			CACHE_LINE_SIZE, socket_id);
	if (lpm == NULL) {
		RTE_LOG(ERR, LPM, "LPM memory allocation failed\n");
		return NULL;
	}

	/* Save user arguments. */
	lpm->max_rules_per_depth = max_rules / RTE_LPM_MAX_DEPTH;
	rte_snprintf(lpm->name, sizeof(lpm->name), "%s", name);

	TAILQ_INSERT_TAIL(lpm_list, lpm, next);

	return lpm;
}

/*
 * Deallocates memory for given LPM table.
 */
void
rte_lpm_free(struct rte_lpm *lpm)
{
	/* Check user arguments. */
	if (lpm == NULL)
		return;

	RTE_EAL_TAILQ_REMOVE(RTE_TAILQ_LPM, rte_lpm_list, lpm);
	rte_free(lpm);
}

/*
 * Adds a rule to the rule table.
 *
 * NOTE: The rule table is split into 32 groups. Each group contains rules that
 * apply to a specific prefix depth (i.e. group 1 contains rules that apply to
 * prefixes with a depth of 1 etc.). In the following code (depth - 1) is used
 * to refer to depth 1 because even though the depth range is 1 - 32, depths
 * are stored in the rule table from 0 - 31.
 * NOTE: Valid range for depth parameter is 1 .. 32 inclusive.
 */
static inline int32_t
rule_add(struct rte_lpm *lpm, uint32_t ip_masked, uint8_t depth,
	uint8_t next_hop)
{
	uint32_t rule_gindex, rule_index, last_rule;

	VERIFY_DEPTH(depth);

	/* rule_gindex stands for rule group index. */
	rule_gindex = ((depth - 1) * lpm->max_rules_per_depth);
	/* Initialise rule_index to point to start of rule group. */
	rule_index = rule_gindex;
	/* Last rule = Last used rule in this rule group. */
	last_rule = rule_gindex + lpm->used_rules_at_depth[depth - 1];
		
	/* Scan through rule group to see if rule already exists. */
	for (rule_index = rule_gindex; rule_index < last_rule; rule_index++) {

		/* If rule already exists update its next_hop and return. */
		if (lpm->rules_tbl[rule_index].ip == ip_masked) {
			lpm->rules_tbl[rule_index].next_hop = next_hop;

			return rule_index;
		}
	}

	/*
	 * If rule does not exist check if there is space to add a new rule to
	 * this rule group. If there is no space return error. */
	if (lpm->used_rules_at_depth[depth - 1] == lpm->max_rules_per_depth) {
		return -ENOSPC;
	}

	/* If there is space for the new rule add it. */
	lpm->rules_tbl[rule_index].ip = ip_masked;
	lpm->rules_tbl[rule_index].next_hop = next_hop;

	/* Increment the used rules counter for this rule group. */
	lpm->used_rules_at_depth[depth - 1]++;

	return rule_index;
}

/*
 * Delete a rule from the rule table.
 * NOTE: Valid range for depth parameter is 1 .. 32 inclusive.
 */
static inline void
rule_delete(struct rte_lpm *lpm, int32_t rule_index, uint8_t depth)
{
	uint32_t rule_gindex, last_rule_index;

	VERIFY_DEPTH(depth);

	rule_gindex = ((depth - 1) * lpm->max_rules_per_depth);
	last_rule_index = rule_gindex +
			(lpm->used_rules_at_depth[depth - 1]) - 1;
	/*
	 * Overwrite redundant rule with last rule in group and decrement rule
	 * counter.
	 */
	lpm->rules_tbl[rule_index] = lpm->rules_tbl[last_rule_index];
	lpm->used_rules_at_depth[depth - 1]--;
}


/*
 * Finds a rule in rule table.
 * NOTE: Valid range for depth parameter is 1 .. 32 inclusive.
 */
static inline int32_t
rule_find(struct rte_lpm *lpm, uint32_t ip_masked, uint8_t depth)
{
	uint32_t rule_gindex, last_rule, rule_index;

	VERIFY_DEPTH(depth);

	rule_gindex = ((depth - 1) * lpm->max_rules_per_depth);
	last_rule = rule_gindex + lpm->used_rules_at_depth[depth - 1];

	/* Scan used rules at given depth to find rule. */
	for (rule_index = rule_gindex; rule_index < last_rule; rule_index++) {
		/* If rule is found return the rule index. */
		if (lpm->rules_tbl[rule_index].ip == ip_masked)
			return (rule_index);
	}

	/* If rule is not found return -E_RTE_NO_TAILQ. */
	return -E_RTE_NO_TAILQ;
}

/*
 * Find, clean and allocate a tbl8.
 */
static inline int32_t
tbl8_alloc(struct rte_lpm_tbl8_entry *tbl8)
{
	uint32_t tbl8_gindex; /* tbl8 group index. */
	struct rte_lpm_tbl8_entry *tbl8_entry;

	/* Scan through tbl8 to find a free (i.e. INVALID) tbl8 group. */
	for (tbl8_gindex = 0; tbl8_gindex < RTE_LPM_TBL8_NUM_GROUPS;
			tbl8_gindex++) {
		tbl8_entry = &tbl8[tbl8_gindex *
		                   RTE_LPM_TBL8_GROUP_NUM_ENTRIES];
		/* If a free tbl8 group is found clean it and set as VALID. */
		if (!tbl8_entry->valid_group) {
			memset(&tbl8_entry[0], 0,
					RTE_LPM_TBL8_GROUP_NUM_ENTRIES *
					sizeof(tbl8_entry[0]));

			tbl8_entry->valid_group = VALID;

			/* Return group index for allocated tbl8 group. */
			return tbl8_gindex;
		}
	}

	/* If there are no tbl8 groups free then return error. */
	return -ENOSPC;
}

static inline void
tbl8_free(struct rte_lpm_tbl8_entry *tbl8, uint32_t tbl8_group_start)
{
	/* Set tbl8 group invalid*/
	tbl8[tbl8_group_start].valid_group = INVALID;
}

static inline int32_t
add_depth_small(struct rte_lpm *lpm, uint32_t ip, uint8_t depth,
		uint8_t next_hop)
{
	uint32_t tbl24_index, tbl24_range, tbl8_index, tbl8_group_end, i, j;

	/* Calculate the index into Table24. */
	tbl24_index = ip >> 8;
	tbl24_range = depth_to_range(depth);

	for (i = tbl24_index; i < (tbl24_index + tbl24_range); i++) {
		/*
		 * For invalid OR valid and non-extended tbl 24 entries set
		 * entry.
		 */
		if (!lpm->tbl24[i].valid || (lpm->tbl24[i].ext_entry == 0 &&
				lpm->tbl24[i].depth <= depth)) {

			struct rte_lpm_tbl24_entry new_tbl24_entry = {
				{ .next_hop = next_hop, },
				.valid = VALID,
				.ext_entry = 0,
				.depth = depth,
			};

			/* Setting tbl24 entry in one go to avoid race
			 * conditions */
			lpm->tbl24[i] = new_tbl24_entry;

			continue;
		}

		/* If tbl24 entry is valid and extended calculate the index
		 * into tbl8. */
		tbl8_index = lpm->tbl24[tbl24_index].tbl8_gindex * 
				RTE_LPM_TBL8_GROUP_NUM_ENTRIES;
		tbl8_group_end = tbl8_index + RTE_LPM_TBL8_GROUP_NUM_ENTRIES;

		for (j = tbl8_index; j < tbl8_group_end; j++) {
			if (!lpm->tbl8[j].valid ||
					lpm->tbl8[j].depth <= depth) {
				struct rte_lpm_tbl8_entry new_tbl8_entry = {
					.valid = VALID,
					.valid_group = VALID,
					.depth = depth,
					.next_hop = next_hop,
				};

				/*
				 * Setting tbl8 entry in one go to avoid race
				 * conditions
				 */
				lpm->tbl8[j] = new_tbl8_entry;

				continue;
			}
		}
	}

	return 0;
}

static inline int32_t
add_depth_big(struct rte_lpm *lpm, uint32_t ip_masked, uint8_t depth,
		uint8_t next_hop)
{
	uint32_t tbl24_index;
	int32_t tbl8_group_index, tbl8_group_start, tbl8_group_end, tbl8_index,
		tbl8_range, i;

	tbl24_index = (ip_masked >> 8);
	tbl8_range = depth_to_range(depth);

	if (!lpm->tbl24[tbl24_index].valid) {
		/* Search for a free tbl8 group. */
		tbl8_group_index = tbl8_alloc(lpm->tbl8);

		/* Check tbl8 allocation was successful. */
		if (tbl8_group_index < 0) {
			return tbl8_group_index;
		}

		/* Find index into tbl8 and range. */
		tbl8_index = (tbl8_group_index *
				RTE_LPM_TBL8_GROUP_NUM_ENTRIES) +
				(ip_masked & 0xFF);

		/* Set tbl8 entry. */
		for (i = tbl8_index; i < (tbl8_index + tbl8_range); i++) {
			lpm->tbl8[i].depth = depth;
			lpm->tbl8[i].next_hop = next_hop;
			lpm->tbl8[i].valid = VALID;
		}

		/*
		 * Update tbl24 entry to point to new tbl8 entry. Note: The
		 * ext_flag and tbl8_index need to be updated simultaneously,
		 * so assign whole structure in one go
		 */

		struct rte_lpm_tbl24_entry new_tbl24_entry = {
			{ .tbl8_gindex = (uint8_t)tbl8_group_index, },
			.valid = VALID,
			.ext_entry = 1,
			.depth = 0,
		};

		lpm->tbl24[tbl24_index] = new_tbl24_entry;

	}/* If valid entry but not extended calculate the index into Table8. */
	else if (lpm->tbl24[tbl24_index].ext_entry == 0) {
		/* Search for free tbl8 group. */
		tbl8_group_index = tbl8_alloc(lpm->tbl8);

		if (tbl8_group_index < 0) {
			return tbl8_group_index;
		}

		tbl8_group_start = tbl8_group_index *
				RTE_LPM_TBL8_GROUP_NUM_ENTRIES;
		tbl8_group_end = tbl8_group_start +
				RTE_LPM_TBL8_GROUP_NUM_ENTRIES;

		/* Populate new tbl8 with tbl24 value. */
		for (i = tbl8_group_start; i < tbl8_group_end; i++) {
			lpm->tbl8[i].valid = VALID;
			lpm->tbl8[i].depth = lpm->tbl24[tbl24_index].depth;
			lpm->tbl8[i].next_hop =
					lpm->tbl24[tbl24_index].next_hop;
		}

		tbl8_index = tbl8_group_start + (ip_masked & 0xFF);

		/* Insert new rule into the tbl8 entry. */
		for (i = tbl8_index; i < tbl8_index + tbl8_range; i++) {
			if (!lpm->tbl8[i].valid ||
					lpm->tbl8[i].depth <= depth) {
				lpm->tbl8[i].valid = VALID;
				lpm->tbl8[i].depth = depth;
				lpm->tbl8[i].next_hop = next_hop;

				continue;
			}
		}

		/*
		 * Update tbl24 entry to point to new tbl8 entry. Note: The
		 * ext_flag and tbl8_index need to be updated simultaneously,
		 * so assign whole structure in one go.
		 */

		struct rte_lpm_tbl24_entry new_tbl24_entry = {
				{ .tbl8_gindex = (uint8_t)tbl8_group_index, },
				.valid = VALID,
				.ext_entry = 1,
				.depth = 0,
		};

		lpm->tbl24[tbl24_index] = new_tbl24_entry;

	}
	else { /*
		* If it is valid, extended entry calculate the index into tbl8.
		*/
		tbl8_group_index = lpm->tbl24[tbl24_index].tbl8_gindex;
		tbl8_group_start = tbl8_group_index *
				RTE_LPM_TBL8_GROUP_NUM_ENTRIES;
		tbl8_index = tbl8_group_start + (ip_masked & 0xFF);

		for (i = tbl8_index; i < (tbl8_index + tbl8_range); i++) {

			if (!lpm->tbl8[i].valid ||
					lpm->tbl8[i].depth <= depth) {
				struct rte_lpm_tbl8_entry new_tbl8_entry = {
					.valid = VALID,
					.depth = depth,
					.next_hop = next_hop,
				};

				/*
				 * Setting tbl8 entry in one go to avoid race
				 * condition
				 */
				lpm->tbl8[i] = new_tbl8_entry;

				continue;
			}
		}
	}

	return 0;
}

/*
 * Add a route
 */
int
rte_lpm_add(struct rte_lpm *lpm, uint32_t ip, uint8_t depth,
		uint8_t next_hop)
{
	int32_t rule_index, status = 0;
	uint32_t ip_masked;

	/* Check user arguments. */
	if ((lpm == NULL) || (depth < 1) || (depth > RTE_LPM_MAX_DEPTH))
		return -EINVAL;

	ip_masked = ip & depth_to_mask(depth);

	/* Add the rule to the rule table. */
	rule_index = rule_add(lpm, ip_masked, depth, next_hop);

	/* If the is no space available for new rule return error. */
	if (rule_index < 0) {
		return rule_index;
	}

	if (depth <= MAX_DEPTH_TBL24) {
		status = add_depth_small(lpm, ip_masked, depth, next_hop);
	}
	else { /* If depth > RTE_LPM_MAX_DEPTH_TBL24 */
		status = add_depth_big(lpm, ip_masked, depth, next_hop);

		/*
		 * If add fails due to exhaustion of tbl8 extensions delete
		 * rule that was added to rule table.
		 */
		if (status < 0) {
			rule_delete(lpm, rule_index, depth);

			return status;
		}
	}

	return 0;
}

static inline int32_t
find_previous_rule(struct rte_lpm *lpm, uint32_t ip, uint8_t depth)
{
	int32_t rule_index;
	uint32_t ip_masked;
	uint8_t prev_depth;

	for (prev_depth = (uint8_t)(depth - 1); prev_depth > 0; prev_depth--) {
		ip_masked = ip & depth_to_mask(prev_depth);

		rule_index = rule_find(lpm, ip_masked, prev_depth);

		if (rule_index >= 0)
			return rule_index;
	}

	return -1;
}

static inline int32_t
delete_depth_small(struct rte_lpm *lpm, uint32_t ip_masked,
	uint8_t depth, int32_t sub_rule_index)
{
	uint32_t tbl24_range, tbl24_index, tbl8_group_index, tbl8_index, i, j;
	uint8_t new_depth;

	/* Calculate the range and index into Table24. */
	tbl24_range = depth_to_range(depth);
	tbl24_index = (ip_masked >> 8);

	/*
	 * Firstly check the sub_rule_index. A -1 indicates no replacement rule
	 * and a positive number indicates a sub_rule_index.
	 */
	if (sub_rule_index < 0) {
		/*
		 * If no replacement rule exists then invalidate entries
		 * associated with this rule.
		 */
		for (i = tbl24_index; i < (tbl24_index + tbl24_range); i++) {
			
			if (lpm->tbl24[i].ext_entry == 0 &&
					lpm->tbl24[i].depth <= depth ) {
				lpm->tbl24[i].valid = INVALID;
			}
			else {
				/*
				 * If TBL24 entry is extended, then there has
				 * to be a rule with depth >= 25 in the
				 * associated TBL8 group.
				 */

				tbl8_group_index = lpm->tbl24[i].tbl8_gindex;
				tbl8_index = tbl8_group_index *
						RTE_LPM_TBL8_GROUP_NUM_ENTRIES;

				for (j = tbl8_index; j < (tbl8_index +
					RTE_LPM_TBL8_GROUP_NUM_ENTRIES); j++) {

					if (lpm->tbl8[j].depth <= depth)
						lpm->tbl8[j].valid = INVALID;
				}
			}
		}
	}
	else {
		/*
		 * If a replacement rule exists then modify entries
		 * associated with this rule.
		 */

		/* Calculate depth of sub_rule. */
		new_depth = (uint8_t) (sub_rule_index /
				lpm->max_rules_per_depth);

		struct rte_lpm_tbl24_entry new_tbl24_entry = {
			{.next_hop = lpm->rules_tbl[sub_rule_index].next_hop,},
			.valid = VALID,
			.ext_entry = 0,
			.depth = new_depth,
		};

		struct rte_lpm_tbl8_entry new_tbl8_entry = {
			.valid = VALID,
			.depth = new_depth,
			.next_hop = lpm->rules_tbl
			[sub_rule_index].next_hop,
		};

		for (i = tbl24_index; i < (tbl24_index + tbl24_range); i++) {

			if (lpm->tbl24[i].ext_entry == 0 &&
					lpm->tbl24[i].depth <= depth ) {
				lpm->tbl24[i] = new_tbl24_entry;
			}
			else {
				/*
				 * If TBL24 entry is extended, then there has
				 * to be a rule with depth >= 25 in the
				 * associated TBL8 group.
				 */

				tbl8_group_index = lpm->tbl24[i].tbl8_gindex;
				tbl8_index = tbl8_group_index *
						RTE_LPM_TBL8_GROUP_NUM_ENTRIES;
				
				for (j = tbl8_index; j < (tbl8_index +
					RTE_LPM_TBL8_GROUP_NUM_ENTRIES); j++) {

					if (lpm->tbl8[j].depth <= depth)
						lpm->tbl8[j] = new_tbl8_entry;
				}
			}
		}
	}

	return 0;
}

/*
 * Checks if table 8 group can be recycled.
 *
 * Return of -EEXIST means tbl8 is in use and thus can not be recycled.
 * Return of -EINVAL means tbl8 is empty and thus can be recycled
 * Return of value > -1 means tbl8 is in use but has all the same values and
 * thus can be recycled
 */
static inline int32_t
tbl8_recycle_check(struct rte_lpm_tbl8_entry *tbl8, uint32_t tbl8_group_start)
{
	uint32_t tbl8_group_end, i;
	tbl8_group_end = tbl8_group_start + RTE_LPM_TBL8_GROUP_NUM_ENTRIES;

	/*
	 * Check the first entry of the given tbl8. If it is invalid we know
	 * this tbl8 does not contain any rule with a depth < RTE_LPM_MAX_DEPTH
	 *  (As they would affect all entries in a tbl8) and thus this table
	 *  can not be recycled.
	 */
	if (tbl8[tbl8_group_start].valid) {
		/*
		 * If first entry is valid check if the depth is less than 24
		 * and if so check the rest of the entries to verify that they
		 * are all of this depth.
		 */
		if (tbl8[tbl8_group_start].depth < MAX_DEPTH_TBL24) {
			for (i = (tbl8_group_start + 1); i < tbl8_group_end;
					i++) {

				if (tbl8[i].depth !=
						tbl8[tbl8_group_start].depth) {

					return -EEXIST;
				}
			}
			/* If all entries are the same return the tb8 index */
			return tbl8_group_start;
		}

		return -EEXIST;
	}
	/*
	 * If the first entry is invalid check if the rest of the entries in
	 * the tbl8 are invalid.
	 */
	for (i = (tbl8_group_start + 1); i < tbl8_group_end; i++) {
		if (tbl8[i].valid)
			return -EEXIST;
	}
	/* If no valid entries are found then return -EINVAL. */
	return -EINVAL;
}

static inline int32_t
delete_depth_big(struct rte_lpm *lpm, uint32_t ip_masked,
	uint8_t depth, int32_t sub_rule_index)
{
	uint32_t tbl24_index, tbl8_group_index, tbl8_group_start, tbl8_index,
			tbl8_range, i;
	uint8_t new_depth;
	int32_t tbl8_recycle_index;

	/*
	 * Calculate the index into tbl24 and range. Note: All depths larger
	 * than MAX_DEPTH_TBL24 are associated with only one tbl24 entry.
	 */
	tbl24_index = ip_masked >> 8;

	/* Calculate the index into tbl8 and range. */
	tbl8_group_index = lpm->tbl24[tbl24_index].tbl8_gindex;
	tbl8_group_start = tbl8_group_index * RTE_LPM_TBL8_GROUP_NUM_ENTRIES;
	tbl8_index = tbl8_group_start + (ip_masked & 0xFF);
	tbl8_range = depth_to_range(depth);

	if (sub_rule_index < 0) {
		/*
		 * Loop through the range of entries on tbl8 for which the
		 * rule_to_delete must be removed or modified.
		 */
		for (i = tbl8_index; i < (tbl8_index + tbl8_range); i++) {
			if (lpm->tbl8[i].depth <= depth)
				lpm->tbl8[i].valid = INVALID;
		}
	}
	else {
		new_depth = (uint8_t)(sub_rule_index /
				lpm->max_rules_per_depth);

		/* Set new tbl8 entry. */
		struct rte_lpm_tbl8_entry new_tbl8_entry = {
			.valid = VALID,
			.depth = new_depth,
			.next_hop = lpm->rules_tbl[sub_rule_index].next_hop,
		};

		/*
		 * Loop through the range of entries on tbl8 for which the
		 * rule_to_delete must be modified.
		 */
		for (i = tbl8_index; i < (tbl8_index + tbl8_range); i++) {
			if (lpm->tbl8[i].depth <= depth)
				lpm->tbl8[i] = new_tbl8_entry;
		}
	}

	/*
	 * Check if there are any valid entries in this tbl8 group. If all
	 * tbl8 entries are invalid we can free the tbl8 and invalidate the
	 * associated tbl24 entry.
	 */

	tbl8_recycle_index = tbl8_recycle_check(lpm->tbl8, tbl8_group_start);

	if (tbl8_recycle_index == -EINVAL){
		/* Set tbl24 before freeing tbl8 to avoid race condition. */
		lpm->tbl24[tbl24_index].valid = 0;
		tbl8_free(lpm->tbl8, tbl8_group_start);
	}
	else if (tbl8_recycle_index > -1) {
		/* Update tbl24 entry. */
		struct rte_lpm_tbl24_entry new_tbl24_entry = {
			{ .next_hop = lpm->tbl8[tbl8_recycle_index].next_hop, },
			.valid = VALID,
			.ext_entry = 0,
			.depth = lpm->tbl8[tbl8_recycle_index].depth,
		};

		/* Set tbl24 before freeing tbl8 to avoid race condition. */
		lpm->tbl24[tbl24_index] = new_tbl24_entry;
		tbl8_free(lpm->tbl8, tbl8_group_start);
	}

	return 0;
}

/*
 * Deletes a rule
 */
int
rte_lpm_delete(struct rte_lpm *lpm, uint32_t ip, uint8_t depth)
{
	int32_t rule_to_delete_index, sub_rule_index;
	uint32_t ip_masked;
	/*
	 * Check input arguments. Note: IP must be a positive integer of 32
	 * bits in length therefore it need not be checked.
	 */
	if ((lpm == NULL) || (depth < 1) || (depth > RTE_LPM_MAX_DEPTH)) {
		return -EINVAL;
	}

	ip_masked = ip & depth_to_mask(depth);

	/*
	 * Find the index of the input rule, that needs to be deleted, in the
	 * rule table.
	 */
	rule_to_delete_index = rule_find(lpm, ip_masked, depth);

	/*
	 * Check if rule_to_delete_index was found. If no rule was found the
	 * function rule_find returns -E_RTE_NO_TAILQ.
	 */
	if (rule_to_delete_index < 0)
		return -E_RTE_NO_TAILQ;

	/* Delete the rule from the rule table. */
	rule_delete(lpm, rule_to_delete_index, depth);

	/*
	 * Find rule to replace the rule_to_delete. If there is no rule to
	 * replace the rule_to_delete we return -1 and invalidate the table
	 * entries associated with this rule.
	 */
	sub_rule_index = find_previous_rule(lpm, ip, depth);

	/*
	 * If the input depth value is less than 25 use function
	 * delete_depth_small otherwise use delete_depth_big.
	 */
	if (depth <= MAX_DEPTH_TBL24) {
		return delete_depth_small(lpm, ip_masked, depth,
				sub_rule_index);
	}
	else { /* If depth > MAX_DEPTH_TBL24 */
		return delete_depth_big(lpm, ip_masked, depth, sub_rule_index);
	}
}

/*
 * Delete all rules from the LPM table.
 */
void
rte_lpm_delete_all(struct rte_lpm *lpm)
{
	/* Zero used rules counter. */
	memset(lpm->used_rules_at_depth, 0, sizeof(lpm->used_rules_at_depth));

	/* Zero tbl24. */
	memset(lpm->tbl24, 0, sizeof(lpm->tbl24));

	/* Zero tbl8. */
	memset(lpm->tbl8, 0, sizeof(lpm->tbl8));

	/* Delete all rules form the rules table. */
	memset(lpm->rules_tbl, 0, sizeof(lpm->rules_tbl[0]) *
			(lpm->max_rules_per_depth * RTE_LPM_MAX_DEPTH));
}