Re: [dpdk-dev] [PATCH v2] librte_lpm: Improve performance of the delete and add functions

[Alex Kiselev <alex@therouter.net>]

Please see inline replies

> On Mon, Jul 02, 2018 at 07:42:11PM +0300, Alex Kiselev wrote:
>> There are two major problems with the library:
>> first, there is no need to rebuild the whole LPM tree
>> when a rule is deleted and second, due to the current
>> rules algorithm with complexity O(n) it's almost
>> impossible to deal with large rule sets (50k or so rules).
>> This patch addresses those two issues.

>> Signed-off-by: Alex Kiselev <alex@therouter.net>

> Hi,

> Some initial review comments inline below

> /Bruce
>> ---
>>  lib/librte_lpm/rte_lpm6.c | 1073 ++++++++++++++++++++++++++++++++++-----------
>>  1 file changed, 816 insertions(+), 257 deletions(-)

>> diff --git a/lib/librte_lpm/rte_lpm6.c b/lib/librte_lpm/rte_lpm6.c
>> index 149677eb1..438db0831 100644
>> --- a/lib/librte_lpm/rte_lpm6.c
>> +++ b/lib/librte_lpm/rte_lpm6.c
>> @@ -21,6 +21,10 @@
>>  #include <rte_errno.h>
>>  #include <rte_rwlock.h>
>>  #include <rte_spinlock.h>
>> +#include <rte_hash.h>
>> +#include <rte_hash_crc.h>
>> +#include <rte_mempool.h>
>> +#include <assert.h>
>>  
>>  #include "rte_lpm6.h"
>>  
>> @@ -37,6 +41,9 @@
>>  #define BYTE_SIZE                                 8
>>  #define BYTES2_SIZE                              16
>>  
>> +#define RULE_HASH_TABLE_EXTRA_SPACE             256
>> +#define TBL24_IND                        UINT32_MAX
>> +
>>  #define lpm6_tbl8_gindex next_hop
>>  
>>  /** Flags for setting an entry as valid/invalid. */
>> @@ -70,6 +77,23 @@ struct rte_lpm6_rule {
>>       uint8_t depth; /**< Rule depth. */
>>  };
>>  
>> +/** Rules tbl entry key. */
>> +struct rte_lpm6_rule_key {
>> +     uint8_t ip[RTE_LPM6_IPV6_ADDR_SIZE]; /**< Rule IP address. */
>> +     uint8_t depth; /**< Rule depth. */
>> +};
>> +
>> +/* Header of tbl8 */
>> +struct rte_lpm_tbl8_hdr {
>> +     uint32_t owner_tbl_ind; /**< owner table: TBL24_IND if owner is tbl24,
>> +                                     * otherwise index of tbl8
>> +                                     */
>> +     uint32_t owner_entry_ind; /**< index of the owner table entry where
>> +                                     * pointer to the tbl8 is stored
>> +                                     */
>> +     uint32_t ref_cnt; /**< table reference counter */
>> +};
>> +
>>  /** LPM6 structure. */
>>  struct rte_lpm6 {
>>       /* LPM metadata. */
>> @@ -77,12 +101,18 @@ struct rte_lpm6 {
>>       uint32_t max_rules;              /**< Max number of rules. */
>>       uint32_t used_rules;             /**< Used rules so far. */
>>       uint32_t number_tbl8s;           /**< Number of tbl8s to allocate. */
>> -     uint32_t next_tbl8;              /**< Next tbl8 to be used. */
>>  
>>       /* LPM Tables. */
>> -     struct rte_lpm6_rule *rules_tbl; /**< LPM rules. */
>> +     struct rte_mempool *rules_pool; /**< LPM rules mempool. */
>> +     struct rte_hash *rules_tbl; /**< LPM rules. */
>>       struct rte_lpm6_tbl_entry tbl24[RTE_LPM6_TBL24_NUM_ENTRIES]
>>                       __rte_cache_aligned; /**< LPM tbl24 table. */
>> +
>> +     uint32_t *tbl8_pool; /**< pool of indexes of free tbl8s */
>> +     uint32_t tbl8_pool_pos; /**< current position in the tbl8 pool */
>> +
>> +     struct rte_lpm_tbl8_hdr *tbl8_hdrs; /* array of tbl8 headers */
>> +
>>       struct rte_lpm6_tbl_entry tbl8[0]
>>                       __rte_cache_aligned; /**< LPM tbl8 table. */
>>  };
>> @@ -93,22 +123,130 @@ struct rte_lpm6 {
>>   * and set the rest to 0.
>>   */
>>  static inline void
>> -mask_ip(uint8_t *ip, uint8_t depth)
>> +ip6_mask_addr(uint8_t *ip, uint8_t depth)
>>  {
>> -        int16_t part_depth, mask;
>> -        int i;
>> +     int16_t part_depth, mask;
>> +     int i;
>>  
>> -             part_depth = depth;
>> +     part_depth = depth;
>>  
>> -             for (i = 0; i < RTE_LPM6_IPV6_ADDR_SIZE; i++) {
>> -                     if (part_depth < BYTE_SIZE && part_depth >= 0) {
>> -                             mask = (uint16_t)(~(UINT8_MAX >> part_depth));
>> -                             ip[i] = (uint8_t)(ip[i] & mask);
>> -                     } else if (part_depth < 0) {
>> -                             ip[i] = 0;
>> -                     }
>> -                     part_depth -= BYTE_SIZE;
>> -             }
>> +     for (i = 0; i < RTE_LPM6_IPV6_ADDR_SIZE; i++) {
>> +             if (part_depth < BYTE_SIZE && part_depth >= 0) {
>> +                     mask = (uint16_t)(~(UINT8_MAX >> part_depth));
>> +                     ip[i] = (uint8_t)(ip[i] & mask);
>> +             } else if (part_depth < 0)
>> +                     ip[i] = 0;
>> +
>> +             part_depth -= BYTE_SIZE;
>> +     }
>> +}

> This block is just a whitespace cleanup, as far as I can see. If there are
> other little cleanups like that as part of this set, it would be nice to
> have them as a separate initial patch, to make it easier to review the more
> complicated changes.
If I am not mistaken there was only one place that needed cleanup.


>> +
>> +/* copy ipv6 address */
>> +static inline void
>> +ip6_copy_addr(uint8_t *dst, const uint8_t *src)
>> +{
>> +     rte_memcpy(dst, src, RTE_LPM6_IPV6_ADDR_SIZE);
>> +}
>> +
>> +/*
>> + * LPM6 rule hash function
>> + */
>> +static inline uint32_t
>> +rule_hash_crc(const void *data, __rte_unused uint32_t data_len,
>> +               uint32_t init_val)
>> +{
>> +     return rte_hash_crc(data, sizeof(struct rte_lpm6_rule_key), init_val);
>> +}

> Why bother passing in the length and making the data a void pointer.
 
I beleive it should be compatible with the rte_hash_function prototype.

> Why
> not just have the prototype:
> rule_hash_crc(struct rte_lpm6_rule_key *data, uint32_t init_val)


>> +
>> +/*
>> + * Init pool of free tbl8 indexes
>> + */
>> +static void
>> +tbl8_pool_init(struct rte_lpm6 *lpm)
>> +{
>> +     /* put entire range of indexes to the tbl8 pool */
>> +     uint32_t i;
>> +     for (i = 0; i < lpm->number_tbl8s; i++)
>> +             lpm->tbl8_pool[i] = i;
>> +
>> +     lpm->tbl8_pool_pos = 0;
>> +}
>> +
>> +/*
>> + * Get an index of a free tbl8 from the pool
>> + */
>> +static inline uint32_t
>> +tbl8_get(struct rte_lpm6 *lpm, uint32_t *tbl8_ind)
>> +{
>> +     if (lpm->tbl8_pool_pos == lpm->number_tbl8s)
>> +             /* no more free tbl8 */
>> +             return -ENOSPC;
>> +
>> +     /* next index */
>> +     *tbl8_ind = lpm->tbl8_pool[lpm->tbl8_pool_pos++];
>> +     return 0;
>> +}
>> +
>> +/*
>> + * Put an index of a free tbl8 back to the pool
>> + */
>> +static inline uint32_t
>> +tbl8_put(struct rte_lpm6 *lpm, uint32_t tbl8_ind)
>> +{
>> +     if (lpm->tbl8_pool_pos == 0)
>> +             /* pool is full */
>> +             return -ENOSPC;
>> +
>> +     lpm->tbl8_pool[--lpm->tbl8_pool_pos] = tbl8_ind;
>> +     return 0;
>> +}
>> +
>> +/*
>> + * Returns number of tbl8s awailable in the pool

> Typo: available
ok, I'll fix it.

>> + */
>> +static inline uint32_t
>> +tbl8_available(struct rte_lpm6 *lpm)
>> +{
>> +     return lpm->number_tbl8s - lpm->tbl8_pool_pos;
>> +}
>> +
>> +/*
>> + * Init a rule key.
>> + *           note that ip must be already masked
>> + */
>> +static inline void
>> +rule_key_init(struct rte_lpm6_rule_key *key, uint8_t *ip, uint8_t depth)
>> +{
>> +     ip6_copy_addr(key->ip, ip);
>> +     key->depth = depth;
>> +}
>> +
>> +/*
>> + * Recreate the entire LPM tree by reinserting all rules
>> + */
>> +static void
>> +recreate_lpm(struct rte_lpm6 *lpm)
>> +{
>> +     struct rte_lpm6_rule *rule;
>> +     struct rte_lpm6_rule *rule_key;
>> +     uint32_t iter = 0;
>> +     while (rte_hash_iterate(lpm->rules_tbl, (const void **) &rule_key,
>> +                     (void **) &rule, &iter) >= 0)
>> +             rte_lpm6_add(lpm, rule->ip, rule->depth, rule->next_hop);
>> +}
>> +
>> +/*
>> + *   Free all rules
>> + */
>> +static void
>> +rules_free(struct rte_lpm6 *lpm)
>> +{
>> +     struct rte_lpm6_rule *rule;
>> +     struct rte_lpm6_rule *rule_key;
>> +     uint32_t iter = 0;
>> +     while (rte_hash_iterate(lpm->rules_tbl, (const void **) &rule_key,
>> +                     (void **) &rule, &iter) >= 0)
>> +             rte_mempool_put(lpm->rules_pool, rule);
>>  }
>>  
>>  /*
>> @@ -121,7 +259,7 @@ rte_lpm6_create(const char *name, int socket_id,
>>       char mem_name[RTE_LPM6_NAMESIZE];
>>       struct rte_lpm6 *lpm = NULL;
>>       struct rte_tailq_entry *te;
>> -     uint64_t mem_size, rules_size;
>> +     uint64_t mem_size;
>>       struct rte_lpm6_list *lpm_list;
>>  
>>       lpm_list = RTE_TAILQ_CAST(rte_lpm6_tailq.head, rte_lpm6_list);
>> @@ -136,12 +274,72 @@ rte_lpm6_create(const char *name, int socket_id,
>>               return NULL;
>>       }
>>  
>> +     struct rte_mempool *rules_mempool = NULL;
>> +     struct rte_hash *rules_tbl = NULL;
>> +     uint32_t *tbl8_pool = NULL;
>> +     struct rte_lpm_tbl8_hdr *tbl8_hdrs = NULL;
>> +
>> +     /* allocate rules mempool */
>> +     snprintf(mem_name, sizeof(mem_name), "LRM_%s", name);

> LRM == "LPM Rules Mempool" I assume? [Not that it actually matters]
yes


>> +     rules_mempool = rte_mempool_create(mem_name,
>> +                     config->max_rules, sizeof(struct rte_lpm6_rule), 0, 0,
>> +                     NULL, NULL, NULL, NULL, socket_id,
>> +                     MEMPOOL_F_NO_CACHE_ALIGN);
>> +     if (rules_mempool == NULL) {
>> +             RTE_LOG(ERR, LPM, "LPM rules mempool allocation failed: %s (%d)",
>> +                               rte_strerror(rte_errno), rte_errno);
>> +             rte_errno = ENOMEM;
>> +             goto fail_wo_unlock;
>> +     }
>> +
>> +     /* create rules hash table */
>> +     snprintf(mem_name, sizeof(mem_name), "LRH_%s", name);
>> +
>> +     struct rte_hash_parameters rule_hash_tbl_params = {
>> +             .entries = config->max_rules + RULE_HASH_TABLE_EXTRA_SPACE,

> Are 256 extra slots going to be enough here? Would it be safer to multiply
> max_rules by e.g. 1.2 or similar?
yes. it would be safer.


>> +             .key_len = sizeof(struct rte_lpm6_rule_key),
>> +             .hash_func = rule_hash_crc,

> Given that this is not for data plane use, it might be better to use jhash
> as the hash function. It's slower, but it does give a better rule
> distribution so allows more compact tables.
yeah, good idea 


>> +             .hash_func_init_val = 0,
>> +             .name = mem_name,
>> +             .reserved = 0,
>> +             .socket_id = socket_id,
>> +             .extra_flag = 0
>> +     };
>> +
>> +     rules_tbl = rte_hash_create(&rule_hash_tbl_params);
>> +     if (rules_tbl == NULL) {
>> +             RTE_LOG(ERR, LPM, "LPM rules hash table allocation failed: %s (%d)",
>> +                               rte_strerror(rte_errno), rte_errno);
>> +             goto fail_wo_unlock;
>> +     }
>> +
>> +     /* allocate tbl8 indexes pool */
>> +     tbl8_pool = rte_malloc(NULL,
>> +                     sizeof(uint32_t) * config->number_tbl8s,
>> +                     RTE_CACHE_LINE_SIZE);
>> +     if (tbl8_pool == NULL) {
>> +             RTE_LOG(ERR, LPM, "LPM tbl8 pool allocation failed: %s (%d)",
>> +                               rte_strerror(rte_errno), rte_errno);
>> +             rte_errno = ENOMEM;
>> +             goto fail_wo_unlock;
>> +     }
>> +
>> +     /* allocate tbl8 headers */
>> +     tbl8_hdrs = rte_malloc(NULL,
>> +                     sizeof(struct rte_lpm_tbl8_hdr) * config->number_tbl8s,
>> +                     RTE_CACHE_LINE_SIZE);
>> +     if (tbl8_hdrs == NULL) {
>> +             RTE_LOG(ERR, LPM, "LPM tbl8 headers allocation failed: %s (%d)",
>> +                               rte_strerror(rte_errno), rte_errno);
>> +             rte_errno = ENOMEM;
>> +             goto fail_wo_unlock;
>> +     }
>> +
>>       snprintf(mem_name, sizeof(mem_name), "LPM_%s", name);
>>  
>>       /* Determine the amount of memory to allocate. */
>>       mem_size = sizeof(*lpm) + (sizeof(lpm->tbl8[0]) *
>>                       RTE_LPM6_TBL8_GROUP_NUM_ENTRIES * config->number_tbl8s);
>> -     rules_size = sizeof(struct rte_lpm6_rule) * config->max_rules;
>>  
>>       rte_rwlock_write_lock(RTE_EAL_TAILQ_RWLOCK);
>>  
>> @@ -154,7 +352,7 @@ rte_lpm6_create(const char *name, int socket_id,
>>       lpm = NULL;
>>       if (te != NULL) {
>>               rte_errno = EEXIST;
>> -             goto exit;
>> +             goto fail;
>>       }
>>  
>>       /* allocate tailq entry */
>> @@ -162,30 +360,18 @@ rte_lpm6_create(const char *name, int socket_id,
>>       if (te == NULL) {
>>               RTE_LOG(ERR, LPM, "Failed to allocate tailq entry!\n");
>>               rte_errno = ENOMEM;
>> -             goto exit;
>> +             goto fail;
>>       }
>>  
>>       /* Allocate memory to store the LPM data structures. */
>> -     lpm = rte_zmalloc_socket(mem_name, (size_t)mem_size,
>> +     lpm = (struct rte_lpm6 *)rte_zmalloc_socket(mem_name, (size_t)mem_size,
>>                       RTE_CACHE_LINE_SIZE, socket_id);
>>  
>>       if (lpm == NULL) {
>>               RTE_LOG(ERR, LPM, "LPM memory allocation failed\n");
>>               rte_free(te);
>>               rte_errno = ENOMEM;
>> -             goto exit;
>> -     }
>> -
>> -     lpm->rules_tbl = rte_zmalloc_socket(NULL,
>> -                     (size_t)rules_size, RTE_CACHE_LINE_SIZE, socket_id);
>> -
>> -     if (lpm->rules_tbl == NULL) {
>> -             RTE_LOG(ERR, LPM, "LPM rules_tbl allocation failed\n");
>> -             rte_free(lpm);
>> -             lpm = NULL;
>> -             rte_free(te);
>> -             rte_errno = ENOMEM;
>> -             goto exit;
>> +             goto fail;
>>       }
>>  
>>       /* Save user arguments. */
>> @@ -193,14 +379,37 @@ rte_lpm6_create(const char *name, int socket_id,
>>       lpm->number_tbl8s = config->number_tbl8s;
>>       snprintf(lpm->name, sizeof(lpm->name), "%s", name);
>>  
>> +     lpm->rules_tbl = rules_tbl;
>> +     lpm->tbl8_pool = tbl8_pool;
>> +     lpm->tbl8_hdrs = tbl8_hdrs;
>> +     lpm->rules_pool = rules_mempool;
>> +
>> +     /* init the stack */
>> +     tbl8_pool_init(lpm);
>> +
>>       te->data = (void *) lpm;
>>  
>>       TAILQ_INSERT_TAIL(lpm_list, te, next);
>> +     rte_rwlock_write_unlock(RTE_EAL_TAILQ_RWLOCK);
>> +     return lpm;
>>  
>> -exit:
>> +fail:
>>       rte_rwlock_write_unlock(RTE_EAL_TAILQ_RWLOCK);
>>  
>> -     return lpm;
>> +fail_wo_unlock:
>> +     if (rules_mempool != NULL)
>> +             rte_mempool_free(rules_mempool);
>> +
>> +     if (tbl8_hdrs != NULL)
>> +             rte_free(tbl8_hdrs);
>> +
>> +     if (tbl8_pool != NULL)
>> +             rte_free(tbl8_pool);
>> +
>> +     if (rules_tbl != NULL)
>> +             rte_hash_free(rules_tbl);
>> +

> rte_free doesn't have an issue with taking NULL as parameter, so you can
> omit the various NULL checks and just have the series of free calls.
got it

>> +     return NULL;
>>  }
>>  
>>  /*
>> @@ -259,50 +468,93 @@ rte_lpm6_free(struct rte_lpm6 *lpm)
>>  
>>       rte_rwlock_write_unlock(RTE_EAL_TAILQ_RWLOCK);
>>  
>> -     rte_free(lpm->rules_tbl);
>> +     rte_mempool_free(lpm->rules_pool);
>> +     rte_free(lpm->tbl8_hdrs);
>> +     rte_free(lpm->tbl8_pool);
>> +     rte_hash_free(lpm->rules_tbl);
>>       rte_free(lpm);
>>       rte_free(te);
>>  }
>>  
>> +/* Find a rule */
>> +static inline struct rte_lpm6_rule*
>> +rule_find_with_key(struct rte_lpm6 *lpm,
>> +               const struct rte_lpm6_rule_key *rule_key)
>> +{
>> +     /* look for a rule */
>> +     struct rte_lpm6_rule    *rule;
>> +     int ret = rte_hash_lookup_data(lpm->rules_tbl,
>> +             (const void *) rule_key, (void **) &rule);
>> +     return (ret >= 0) ? rule : NULL;
>> +}
>> +
>> +/* Find a rule */
>> +static struct rte_lpm6_rule*
>> +rule_find(struct rte_lpm6 *lpm, uint8_t *ip, uint8_t depth)
>> +{
>> +     /* init a rule key */
>> +     struct rte_lpm6_rule_key rule_key;
>> +     rule_key_init(&rule_key, ip, depth);
>> +
>> +     return rule_find_with_key(lpm, &rule_key);
>> +}
>> +
>>  /*
>>   * Checks if a rule already exists in the rules table and updates
>>   * the nexthop if so. Otherwise it adds a new rule if enough space is available.
>> + *
>> + * Returns:
>> + *    0 - next hop of existed rule is updated
>> + *    1 - new rule successfuly added
>> + *   <0 - error
>>   */
>> -static inline int32_t
>> -rule_add(struct rte_lpm6 *lpm, uint8_t *ip, uint32_t next_hop, uint8_t depth)
>> +static inline int
>> +rule_add(struct rte_lpm6 *lpm, uint8_t *ip, uint8_t depth, uint32_t next_hop)
>>  {
>> -     uint32_t rule_index;
>> +     /* init a rule key */
>> +     struct rte_lpm6_rule_key rule_key;
>> +     rule_key_init(&rule_key, ip, depth);
>>  
>>       /* Scan through rule list to see if rule already exists. */
>> -     for (rule_index = 0; rule_index < lpm->used_rules; rule_index++) {
>> -
>> -             /* If rule already exists update its next_hop and return. */
>> -             if ((memcmp (lpm->rules_tbl[rule_index].ip, ip,
>> -                             RTE_LPM6_IPV6_ADDR_SIZE) == 0) &&
>> -                             lpm->rules_tbl[rule_index].depth == depth) {
>> -                     lpm->rules_tbl[rule_index].next_hop = next_hop;
>> +     struct rte_lpm6_rule *rule = rule_find_with_key(lpm, &rule_key);
>>  
>> -                     return rule_index;
>> -             }
>> +     /* If rule already exists update its next_hop and return. */
>> +     if (rule != NULL) {
>> +             rule->next_hop = next_hop;
>> +             return 0;
>>       }
>>  
>>       /*
>>        * 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 == lpm->max_rules) {
>> +     if (lpm->used_rules == lpm->max_rules)
>>               return -ENOSPC;
>> -     }
>>  
>> -     /* If there is space for the new rule add it. */
>> -     rte_memcpy(lpm->rules_tbl[rule_index].ip, ip, RTE_LPM6_IPV6_ADDR_SIZE);
>> -     lpm->rules_tbl[rule_index].next_hop = next_hop;
>> -     lpm->rules_tbl[rule_index].depth = depth;
>> +     /*
>> +      * If there is space for the new rule add it.
>> +      */
>> +
>> +     /* get a new rule */
>> +     int ret = rte_mempool_get(lpm->rules_pool, (void **) &rule);
>> +     if (ret < 0)
>> +             return ret;
>> +
>> +     /* init the rule */
>> +     rule->depth = depth;
>> +     ip6_copy_addr(rule->ip, ip);
>> +     rule->next_hop = next_hop;
>> +
>> +     /* add the rule */
>> +     ret = rte_hash_add_key_data(lpm->rules_tbl, &rule_key, rule);
>> +     if (ret < 0) {
>> +             rte_mempool_put(lpm->rules_pool, rule);
>> +             return ret;
>> +     }
>>  
>>       /* Increment the used rules counter for this rule group. */
>>       lpm->used_rules++;
>> -
>> -     return rule_index;
>> +     return 1;
>>  }
>>  
>>  /*
>> @@ -311,24 +563,24 @@ rule_add(struct rte_lpm6 *lpm, uint8_t *ip, uint32_t next_hop, uint8_t depth)
>>   * in the IP address returns a match.
>>   */
>>  static void
>> -expand_rule(struct rte_lpm6 *lpm, uint32_t tbl8_gindex, uint8_t depth,
>> -             uint32_t next_hop)
>> +expand_rule(struct rte_lpm6 *lpm, uint32_t tbl8_gindex, uint8_t old_depth,
>> +             uint8_t new_depth, uint32_t next_hop, uint8_t valid)

> Is this change to have separate old depths and new depths a bug fix for an
> existing issue, or just a change needed due to the rework below?

It's not a bug fix. the function is now used not only in the add rule, 
but in delete rule operation too, which requires a little bit 
more complicated logic. 

>>  {
>>       uint32_t tbl8_group_end, tbl8_gindex_next, j;
>>  
>>       tbl8_group_end = tbl8_gindex + RTE_LPM6_TBL8_GROUP_NUM_ENTRIES;
>>  
>>       struct rte_lpm6_tbl_entry new_tbl8_entry = {
>> -             .valid = VALID,
>> -             .valid_group = VALID,
>> -             .depth = depth,
>> +             .valid = valid,
>> +             .valid_group = valid,
>> +             .depth = new_depth,
>>               .next_hop = next_hop,
>>               .ext_entry = 0,
>>       };
>>  
>>       for (j = tbl8_gindex; j < tbl8_group_end; j++) {
>>               if (!lpm->tbl8[j].valid || (lpm->tbl8[j].ext_entry == 0
>> -                             && lpm->tbl8[j].depth <= depth)) {
>> +                             && lpm->tbl8[j].depth <= old_depth)) {
>>  
>>                       lpm->tbl8[j] = new_tbl8_entry;
>>  
>> @@ -336,11 +588,101 @@ expand_rule(struct rte_lpm6 *lpm, uint32_t tbl8_gindex, uint8_t depth,
>>  
>>                       tbl8_gindex_next = lpm->tbl8[j].lpm6_tbl8_gindex
>>                                       * RTE_LPM6_TBL8_GROUP_NUM_ENTRIES;
>> -                     expand_rule(lpm, tbl8_gindex_next, depth, next_hop);
>> +                     expand_rule(lpm, tbl8_gindex_next, old_depth, new_depth,
>> +                                     next_hop, valid);
>>               }
>>       }
>>  }
>>  
>> +/*
>> + * Init a tbl8 header
>> + */
>> +static inline void
>> +init_tbl8_header(struct rte_lpm6 *lpm, uint32_t tbl_ind,
>> +             uint32_t owner_tbl_ind, uint32_t owner_entry_ind)
>> +{
>> +     struct rte_lpm_tbl8_hdr *tbl_hdr = &lpm->tbl8_hdrs[tbl_ind];
>> +     tbl_hdr->owner_tbl_ind = owner_tbl_ind;
>> +     tbl_hdr->owner_entry_ind = owner_entry_ind;
>> +     tbl_hdr->ref_cnt = 0;
>> +}
>> +
>> +/*
>> + * Calculate index to the table based on the number and position
>> + * of the bytes being inspected in this step.
>> + */
>> +static uint32_t
>> +get_bitshift(const uint8_t *ip, uint8_t first_byte, uint8_t bytes)
>> +{
>> +     uint32_t entry_ind, i;
>> +     int8_t bitshift;
>> +
>> +     entry_ind = 0;
>> +     for (i = first_byte; i < (uint32_t)(first_byte + bytes); i++) {
>> +             bitshift = (int8_t)((bytes - i)*BYTE_SIZE);
>> +
>> +             if (bitshift < 0)
>> +                     bitshift = 0;
>> +             entry_ind = entry_ind | ip[i-1] << bitshift;
>> +     }
>> +
>> +     return entry_ind;
>> +}
>> +
>> +/*
>> + * Simulate adding a new route to the LPM counting number
>> + * of new tables that will be needed
>> + *
>> + * It returns 0 on success, or 1 if
>> + * the process needs to be continued by calling the function again.
>> + */
>> +static inline int
>> +simulate_add_step(struct rte_lpm6 *lpm, struct rte_lpm6_tbl_entry *tbl,
>> +             struct rte_lpm6_tbl_entry **next_tbl, const uint8_t *ip,
>> +             uint8_t bytes, uint8_t first_byte, uint8_t depth,
>> +             uint32_t *need_tbl_nb)
>> +{
>> +     uint32_t entry_ind;
>> +     uint8_t bits_covered;
>> +     uint32_t next_tbl_ind;
>> +
>> +     /*
>> +      * Calculate index to the table based on the number and position
>> +      * of the bytes being inspected in this step.
>> +      */
>> +     entry_ind = get_bitshift(ip, first_byte, bytes);
>> +
>> +     /* Number of bits covered in this step */
>> +     bits_covered = (uint8_t)((bytes+first_byte-1)*BYTE_SIZE);
>> +
>> +     if (depth <= bits_covered) {
>> +             *need_tbl_nb = 0;
>> +             return 0;
>> +     }
>> +
>> +     if (tbl[entry_ind].valid == 0 || tbl[entry_ind].ext_entry == 0) {
>> +             /* from this point on a new table is needed on each level
>> +              * that is not covered yet
>> +              */
>> +             depth -= bits_covered;
>> +             uint32_t cnt = depth >> 3; /* depth / 3 */

> depth / 8, not / 3. Perhaps "/ BYTE_SIZE" might be best.

>> +             if (depth & 7) /* 0b00000111 */
>> +                     /* if depth % 8 > 0 then one more table is needed
>> +                      * for those last bits
>> +                      */
>> +                     cnt++;
>> +
>> +             *need_tbl_nb = cnt;
>> +             return 0;
>> +     }
>> +
>> +     next_tbl_ind = tbl[entry_ind].lpm6_tbl8_gindex;
>> +     *next_tbl = &(lpm->tbl8[next_tbl_ind *
>> +             RTE_LPM6_TBL8_GROUP_NUM_ENTRIES]);
>> +     *need_tbl_nb = 0;
>> +     return 1;
>> +}
>> +
>>  /*
>>   * Partially adds a new route to the data structure (tbl24+tbl8s).
>>   * It returns 0 on success, a negative number on failure, or 1 if
>> @@ -348,25 +690,21 @@ expand_rule(struct rte_lpm6 *lpm, uint32_t tbl8_gindex, uint8_t depth,
>>   */
>>  static inline int
>>  add_step(struct rte_lpm6 *lpm, struct rte_lpm6_tbl_entry *tbl,
>> -             struct rte_lpm6_tbl_entry **tbl_next, uint8_t *ip, uint8_t bytes,
>> -             uint8_t first_byte, uint8_t depth, uint32_t next_hop)
>> +             uint32_t tbl_ind, struct rte_lpm6_tbl_entry **next_tbl,
>> +             uint32_t *next_tbl_ind, uint8_t *ip, uint8_t bytes,
>> +             uint8_t first_byte, uint8_t depth, uint32_t next_hop,
>> +             uint8_t is_new_rule)
>>  {
>> -     uint32_t tbl_index, tbl_range, tbl8_group_start, tbl8_group_end, i;
>> -     int32_t tbl8_gindex;
>> -     int8_t bitshift;
>> +     uint32_t entry_ind, tbl_range, tbl8_group_start, tbl8_group_end, i;
>> +     uint32_t tbl8_gindex;
>>       uint8_t bits_covered;
>> +     int ret;
>>  
>>       /*
>>        * Calculate index to the table based on the number and position
>>        * of the bytes being inspected in this step.
>>        */
>> -     tbl_index = 0;
>> -     for (i = first_byte; i < (uint32_t)(first_byte + bytes); i++) {
>> -             bitshift = (int8_t)((bytes - i)*BYTE_SIZE);
>> -
>> -             if (bitshift < 0) bitshift = 0;
>> -             tbl_index = tbl_index | ip[i-1] << bitshift;
>> -     }
>> +     entry_ind = get_bitshift(ip, first_byte, bytes);
>>  
>>       /* Number of bits covered in this step */
>>       bits_covered = (uint8_t)((bytes+first_byte-1)*BYTE_SIZE);
>> @@ -378,7 +716,7 @@ add_step(struct rte_lpm6 *lpm, struct rte_lpm6_tbl_entry *tbl,
>>       if (depth <= bits_covered) {
>>               tbl_range = 1 << (bits_covered - depth);
>>  
>> -             for (i = tbl_index; i < (tbl_index + tbl_range); i++) {
>> +             for (i = entry_ind; i < (entry_ind + tbl_range); i++) {
>>                       if (!tbl[i].valid || (tbl[i].ext_entry == 0 &&
>>                                       tbl[i].depth <= depth)) {
>>  
>> @@ -400,10 +738,15 @@ add_step(struct rte_lpm6 *lpm, struct rte_lpm6_tbl_entry *tbl,
>>                                */
>>                               tbl8_gindex = tbl[i].lpm6_tbl8_gindex *
>>                                               RTE_LPM6_TBL8_GROUP_NUM_ENTRIES;
>> -                             expand_rule(lpm, tbl8_gindex, depth, next_hop);
>> +                             expand_rule(lpm, tbl8_gindex, depth, depth,
>> +                                             next_hop, VALID);
>>                       }
>>               }
>>  
>> +             /* update tbl8 rule reference counter */
>> +             if (tbl_ind != TBL24_IND && is_new_rule)
>> +                     lpm->tbl8_hdrs[tbl_ind].ref_cnt++;
>> +
>>               return 0;
>>       }
>>       /*
>> @@ -412,12 +755,24 @@ add_step(struct rte_lpm6 *lpm, struct rte_lpm6_tbl_entry *tbl,
>>        */
>>       else {
>>               /* If it's invalid a new tbl8 is needed */
>> -             if (!tbl[tbl_index].valid) {
>> -                     if (lpm->next_tbl8 < lpm->number_tbl8s)
>> -                             tbl8_gindex = (lpm->next_tbl8)++;
>> -                     else
>> +             if (!tbl[entry_ind].valid) {
>> +                     /* get a new table */
>> +                     ret = tbl8_get(lpm, &tbl8_gindex);
>> +                     if (ret != 0)
>>                               return -ENOSPC;
>>  
>> +                     /* invalidate all new tbl8 entries */
>> +                     tbl8_group_start = tbl8_gindex *
>> +                                     RTE_LPM6_TBL8_GROUP_NUM_ENTRIES;
>> +                     memset(&lpm->tbl8[tbl8_group_start], 0,
>> +                                       RTE_LPM6_TBL8_GROUP_NUM_ENTRIES);
>> +
>> +                     /* init the new table's header:
>> +                      *   save the reference to the owner table
>> +                      */
>> +                     init_tbl8_header(lpm, tbl8_gindex, tbl_ind, entry_ind);
>> +
>> +                     /* reference to a new tbl8 */
>>                       struct rte_lpm6_tbl_entry new_tbl_entry = {
>>                               .lpm6_tbl8_gindex = tbl8_gindex,
>>                               .depth = 0,
>> @@ -426,17 +781,20 @@ add_step(struct rte_lpm6 *lpm, struct rte_lpm6_tbl_entry *tbl,
>>                               .ext_entry = 1,
>>                       };
>>  
>> -                     tbl[tbl_index] = new_tbl_entry;
>> +                     tbl[entry_ind] = new_tbl_entry;
>> +
>> +                     /* update the current table's reference counter */
>> +                     if (tbl_ind != TBL24_IND)
>> +                             lpm->tbl8_hdrs[tbl_ind].ref_cnt++;
>>               }
>>               /*
>> -              * If it's valid but not extended the rule that was stored *
>> +              * If it's valid but not extended the rule that was stored
>>                * here needs to be moved to the next table.
>>                */
>> -             else if (tbl[tbl_index].ext_entry == 0) {
>> -                     /* Search for free tbl8 group. */
>> -                     if (lpm->next_tbl8 < lpm->number_tbl8s)
>> -                             tbl8_gindex = (lpm->next_tbl8)++;
>> -                     else
>> +             else if (tbl[entry_ind].ext_entry == 0) {
>> +                     /* get a new tbl8 index */
>> +                     ret = tbl8_get(lpm, &tbl8_gindex);
>> +                     if (ret != 0)
>>                               return -ENOSPC;
>>  
>>                       tbl8_group_start = tbl8_gindex *
>> @@ -444,13 +802,22 @@ add_step(struct rte_lpm6 *lpm, struct rte_lpm6_tbl_entry *tbl,
>>                       tbl8_group_end = tbl8_group_start +
>>                                       RTE_LPM6_TBL8_GROUP_NUM_ENTRIES;
>>  
>> +                     struct rte_lpm6_tbl_entry tbl_entry = {
>> +                             .next_hop = tbl[entry_ind].next_hop,
>> +                             .depth = tbl[entry_ind].depth,
>> +                             .valid = VALID,
>> +                             .valid_group = VALID,
>> +                             .ext_entry = 0
>> +                     };
>> +
>>                       /* Populate new tbl8 with tbl value. */
>> -                     for (i = tbl8_group_start; i < tbl8_group_end; i++) {
>> -                             lpm->tbl8[i].valid = VALID;
>> -                             lpm->tbl8[i].depth = tbl[tbl_index].depth;
>> -                             lpm->tbl8[i].next_hop = tbl[tbl_index].next_hop;
>> -                             lpm->tbl8[i].ext_entry = 0;
>> -                     }
>> +                     for (i = tbl8_group_start; i < tbl8_group_end; i++)
>> +                             lpm->tbl8[i] = tbl_entry;
>> +
>> +                     /* init the new table's header:
>> +                      *   save the reference to the owner table
>> +                      */
>> +                     init_tbl8_header(lpm, tbl8_gindex, tbl_ind, entry_ind);
>>  
>>                       /*
>>                        * Update tbl entry to point to new tbl8 entry. Note: The
>> @@ -465,11 +832,16 @@ add_step(struct rte_lpm6 *lpm, struct rte_lpm6_tbl_entry *tbl,
>>                               .ext_entry = 1,
>>                       };
>>  
>> -                     tbl[tbl_index] = new_tbl_entry;
>> +                     tbl[entry_ind] = new_tbl_entry;
>> +
>> +                     /* update the current table's reference counter */
>> +                     if (tbl_ind != TBL24_IND)
>> +                             lpm->tbl8_hdrs[tbl_ind].ref_cnt++;
>>               }
>>  
>> -             *tbl_next = &(lpm->tbl8[tbl[tbl_index].lpm6_tbl8_gindex *
>> -                             RTE_LPM6_TBL8_GROUP_NUM_ENTRIES]);
>> +             *next_tbl_ind = tbl[entry_ind].lpm6_tbl8_gindex;
>> +             *next_tbl = &(lpm->tbl8[*next_tbl_ind *
>> +                               RTE_LPM6_TBL8_GROUP_NUM_ENTRIES]);
>>       }
>>  
>>       return 1;
>> @@ -486,13 +858,55 @@ rte_lpm6_add_v20(struct rte_lpm6 *lpm, uint8_t *ip, uint8_t depth,
>>  }
>>  VERSION_SYMBOL(rte_lpm6_add, _v20, 2.0);
>>  
>> +
>> +/*
>> + * Simulate adding a route to LPM
>> + *
>> + *   Returns:
>> + *           0 if success
>> + *    -ENOSPC not enought tbl8 left
>> + */
>> +static int
>> +simulate_add(struct rte_lpm6 *lpm, const uint8_t *masked_ip, uint8_t depth)
>> +{
>> +     struct rte_lpm6_tbl_entry *tbl;
>> +     struct rte_lpm6_tbl_entry *tbl_next = NULL;
>> +     int ret, i;
>> +
>> +     /* number of new tables needed for a step */
>> +     uint32_t need_tbl_nb;
>> +     /* total number of new tables needed */
>> +     uint32_t total_need_tbl_nb;
>> +
>> +     /* Inspect the first three bytes through tbl24 on the first step. */
>> +     ret = simulate_add_step(lpm, lpm->tbl24, &tbl_next, masked_ip,
>> +                     ADD_FIRST_BYTE, 1, depth, &need_tbl_nb);
>> +     total_need_tbl_nb = need_tbl_nb;
>> +     /*
>> +      * Inspect one by one the rest of the bytes until
>> +      * the process is completed.
>> +      */
>> +     for (i = ADD_FIRST_BYTE; i < RTE_LPM6_IPV6_ADDR_SIZE && ret == 1; i++) {
>> +             tbl = tbl_next;
>> +             ret = simulate_add_step(lpm, tbl, &tbl_next, masked_ip, 1,
>> +                             (uint8_t)(i+1), depth, &need_tbl_nb);
>> +             total_need_tbl_nb += need_tbl_nb;
>> +     }
>> +
>> +     if (tbl8_available(lpm) < total_need_tbl_nb)
>> +             /* not enought tbl8 to add a rule */
>> +             return -ENOSPC;
>> +
>> +     return 0;
>> +}
>> +
>>  int
>>  rte_lpm6_add_v1705(struct rte_lpm6 *lpm, uint8_t *ip, uint8_t depth,
>>               uint32_t next_hop)
>>  {
>>       struct rte_lpm6_tbl_entry *tbl;
>>       struct rte_lpm6_tbl_entry *tbl_next = NULL;
>> -     int32_t rule_index;
>> +     uint32_t tbl_next_num;
>>       int status;
>>       uint8_t masked_ip[RTE_LPM6_IPV6_ADDR_SIZE];
>>       int i;
>> @@ -502,26 +916,26 @@ rte_lpm6_add_v1705(struct rte_lpm6 *lpm, uint8_t *ip, uint8_t depth,
>>               return -EINVAL;
>>  
>>       /* Copy the IP and mask it to avoid modifying user's input data. */
>> -     memcpy(masked_ip, ip, RTE_LPM6_IPV6_ADDR_SIZE);
>> -     mask_ip(masked_ip, depth);
>> +     ip6_copy_addr(masked_ip, ip);
>> +     ip6_mask_addr(masked_ip, depth);
>>  
>>       /* Add the rule to the rule table. */
>> -     rule_index = rule_add(lpm, masked_ip, next_hop, depth);
>> -
>> +     int is_new_rule = rule_add(lpm, masked_ip, depth, next_hop);
>>       /* If there is no space available for new rule return error. */
>> -     if (rule_index < 0) {
>> -             return rule_index;
>> -     }
>> +     if (is_new_rule < 0)
>> +             return is_new_rule;
>> +
>> +     /* Simulate adding a new route */
>> +     int ret = simulate_add(lpm, masked_ip, depth);
>> +     if (ret < 0)
>> +             return ret;

> Do we need any rollback here for the rule that was just added?
yeah, my mistake. definitely, a rollback must be used.


>>  
>>       /* Inspect the first three bytes through tbl24 on the first step. */
>>       tbl = lpm->tbl24;
>> -     status = add_step (lpm, tbl, &tbl_next, masked_ip, ADD_FIRST_BYTE, 1,
>> -                     depth, next_hop);
>> -     if (status < 0) {
>> -             rte_lpm6_delete(lpm, masked_ip, depth);
>> -
>> -             return status;
>> -     }
>> +     status = add_step(lpm, tbl, TBL24_IND, &tbl_next, &tbl_next_num,
>> +                     masked_ip, ADD_FIRST_BYTE, 1, depth, next_hop,
>> +                     is_new_rule);
>> +     assert(status >= 0);
>>  
>>       /*
>>        * Inspect one by one the rest of the bytes until
>> @@ -529,13 +943,10 @@ rte_lpm6_add_v1705(struct rte_lpm6 *lpm, uint8_t *ip, uint8_t depth,
>>        */
>>       for (i = ADD_FIRST_BYTE; i < RTE_LPM6_IPV6_ADDR_SIZE && status == 1; i++) {
>>               tbl = tbl_next;
>> -             status = add_step (lpm, tbl, &tbl_next, masked_ip, 1, (uint8_t)(i+1),
>> -                             depth, next_hop);
>> -             if (status < 0) {
>> -                     rte_lpm6_delete(lpm, masked_ip, depth);
>> -
>> -                     return status;
>> -             }
>> +             status = add_step(lpm, tbl, tbl_next_num, &tbl_next,
>> +                             &tbl_next_num, masked_ip, 1, (uint8_t)(i+1),
>> +                             depth, next_hop, is_new_rule);
>> +             assert(status >= 0);
>>       }
>>  
>>       return status;
>> @@ -610,9 +1021,8 @@ rte_lpm6_lookup_v1705(const struct rte_lpm6 *lpm, uint8_t *ip,
>>       uint32_t tbl24_index;
>>  
>>       /* DEBUG: Check user input arguments. */
>> -     if ((lpm == NULL) || (ip == NULL) || (next_hop == NULL)) {
>> +     if ((lpm == NULL) || (ip == NULL) || (next_hop == NULL))
>>               return -EINVAL;
>> -     }
>>  
>>       first_byte = LOOKUP_FIRST_BYTE;
>>       tbl24_index = (ip[0] << BYTES2_SIZE) | (ip[1] << BYTE_SIZE) | ip[2];
>> @@ -648,9 +1058,8 @@ rte_lpm6_lookup_bulk_func_v20(const struct rte_lpm6 *lpm,
>>       int status;
>>  
>>       /* DEBUG: Check user input arguments. */
>> -     if ((lpm == NULL) || (ips == NULL) || (next_hops == NULL)) {
>> +     if ((lpm == NULL) || (ips == NULL) || (next_hops == NULL))
>>               return -EINVAL;
>> -     }
>>  
>>       for (i = 0; i < n; i++) {
>>               first_byte = LOOKUP_FIRST_BYTE;
>> @@ -724,30 +1133,6 @@ MAP_STATIC_SYMBOL(int rte_lpm6_lookup_bulk_func(const struct rte_lpm6 *lpm,
>>                               int32_t *next_hops, unsigned int n),
>>               rte_lpm6_lookup_bulk_func_v1705);
>>  
>> -/*
>> - * Finds a rule in rule table.
>> - * NOTE: Valid range for depth parameter is 1 .. 128 inclusive.
>> - */
>> -static inline int32_t
>> -rule_find(struct rte_lpm6 *lpm, uint8_t *ip, uint8_t depth)
>> -{
>> -     uint32_t rule_index;
>> -
>> -     /* Scan used rules at given depth to find rule. */
>> -     for (rule_index = 0; rule_index < lpm->used_rules; rule_index++) {
>> -             /* If rule is found return the rule index. */
>> -             if ((memcmp (lpm->rules_tbl[rule_index].ip, ip,
>> -                             RTE_LPM6_IPV6_ADDR_SIZE) == 0) &&
>> -                             lpm->rules_tbl[rule_index].depth == depth) {
>> -
>> -                     return rule_index;
>> -             }
>> -     }
>> -
>> -     /* If rule is not found return -ENOENT. */
>> -     return -ENOENT;
>> -}
>> -
>>  /*
>>   * Look for a rule in the high-level rules table
>>   */
>> @@ -775,23 +1160,20 @@ int
>>  rte_lpm6_is_rule_present_v1705(struct rte_lpm6 *lpm, uint8_t *ip, uint8_t depth,
>>               uint32_t *next_hop)
>>  {
>> -     uint8_t ip_masked[RTE_LPM6_IPV6_ADDR_SIZE];
>> -     int32_t rule_index;
>> -
>>       /* Check user arguments. */
>>       if ((lpm == NULL) || next_hop == NULL || ip == NULL ||
>>                       (depth < 1) || (depth > RTE_LPM6_MAX_DEPTH))
>>               return -EINVAL;
>>  
>>       /* Copy the IP and mask it to avoid modifying user's input data. */
>> -     memcpy(ip_masked, ip, RTE_LPM6_IPV6_ADDR_SIZE);
>> -     mask_ip(ip_masked, depth);
>> +     uint8_t masked_ip[RTE_LPM6_IPV6_ADDR_SIZE];

> The line above doesn't strictly need to be moved. It's still recommended to
> have variables at the top of the block.
ok, I'll move it the top of the block

>> +     ip6_copy_addr(masked_ip, ip);
>> +     ip6_mask_addr(masked_ip, depth);
>>  
>> -     /* Look for the rule using rule_find. */
>> -     rule_index = rule_find(lpm, ip_masked, depth);
>> +     struct rte_lpm6_rule *rule = rule_find(lpm, masked_ip, depth);
>>  

> Can mark this as const, which can help justify having it declared
> mid-block. :-)
ok, I'll move it the top of the block

> <rest snipped>


-- 
Alex