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ovs/lib/classifier.c
Jarno Rajahalme 627fb667b2 lib/classifier: Separate cls_rule internals from the API. 
Keep an internal representation of a rule separate from the one
embedded into user's structs.  This allows for further memory
optimization in the classifier.

Signed-off-by: Jarno Rajahalme <jrajahalme@nicira.com>
Acked-by: Ethan Jackson <ethan@nicira.com>
2014-04-29 15:50:38 -07:00

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/*
* Copyright (c) 2009, 2010, 2011, 2012, 2013 Nicira, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at:
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <config.h>
#include "classifier.h"
#include <errno.h>
#include <netinet/in.h>
#include "byte-order.h"
#include "dynamic-string.h"
#include "flow.h"
#include "hash.h"
#include "odp-util.h"
#include "ofp-util.h"
#include "ovs-thread.h"
#include "packets.h"
#include "vlog.h"
VLOG_DEFINE_THIS_MODULE(classifier);
struct trie_node;
/* Prefix trie for a 'field' */
struct cls_trie {
const struct mf_field *field; /* Trie field, or NULL. */
struct trie_node *root; /* NULL if none. */
};
struct cls_subtable_entry {
struct cls_subtable *subtable;
uint32_t *mask_values;
tag_type tag;
unsigned int max_priority;
};
struct cls_subtable_cache {
struct cls_subtable_entry *subtables;
size_t alloc_size; /* Number of allocated elements. */
size_t size; /* One past last valid array element. */
};
enum {
CLS_MAX_INDICES = 3 /* Maximum number of lookup indices per subtable. */
};
struct cls_classifier {
int n_rules; /* Total number of rules. */
uint8_t n_flow_segments;
uint8_t flow_segments[CLS_MAX_INDICES]; /* Flow segment boundaries to use
* for staged lookup. */
struct hmap subtables; /* Contains "struct cls_subtable"s. */
struct cls_subtable_cache subtables_priority;
struct hmap partitions; /* Contains "struct cls_partition"s. */
struct cls_trie tries[CLS_MAX_TRIES]; /* Prefix tries. */
unsigned int n_tries;
};
/* A set of rules that all have the same fields wildcarded. */
struct cls_subtable {
struct hmap_node hmap_node; /* Within struct cls_classifier 'subtables'
* hmap. */
struct hmap rules; /* Contains "struct cls_rule"s. */
struct minimask mask; /* Wildcards for fields. */
int n_rules; /* Number of rules, including duplicates. */
unsigned int max_priority; /* Max priority of any rule in the subtable. */
unsigned int max_count; /* Count of max_priority rules. */
tag_type tag; /* Tag generated from mask for partitioning. */
uint8_t n_indices; /* How many indices to use. */
uint8_t index_ofs[CLS_MAX_INDICES]; /* u32 flow segment boundaries. */
struct hindex indices[CLS_MAX_INDICES]; /* Staged lookup indices. */
unsigned int trie_plen[CLS_MAX_TRIES]; /* Trie prefix length in 'mask'. */
};
/* Associates a metadata value (that is, a value of the OpenFlow 1.1+ metadata
* field) with tags for the "cls_subtable"s that contain rules that match that
* metadata value. */
struct cls_partition {
struct hmap_node hmap_node; /* In struct cls_classifier's 'partitions'
* hmap. */
ovs_be64 metadata; /* metadata value for this partition. */
tag_type tags; /* OR of each flow's cls_subtable tag. */
struct tag_tracker tracker; /* Tracks the bits in 'tags'. */
};
/* Internal representation of a rule in a "struct cls_subtable". */
struct cls_match {
struct cls_rule *cls_rule;
struct hindex_node index_nodes[CLS_MAX_INDICES]; /* Within subtable's
* 'indices'. */
struct hmap_node hmap_node; /* Within struct cls_subtable 'rules'. */
unsigned int priority; /* Larger numbers are higher priorities. */
struct cls_partition *partition;
struct list list; /* List of identical, lower-priority rules. */
struct minimatch match; /* Matching rule. */
};
static struct cls_match *
cls_match_alloc(struct cls_rule *rule)
{
struct cls_match *cls_match = xmalloc(sizeof *cls_match);
cls_match->cls_rule = rule;
minimatch_clone(&cls_match->match, &rule->match);
cls_match->priority = rule->priority;
rule->cls_match = cls_match;
return cls_match;
}
struct trie_ctx;
static struct cls_subtable *find_subtable(const struct cls_classifier *,
const struct minimask *);
static struct cls_subtable *insert_subtable(struct cls_classifier *,
const struct minimask *);
static void destroy_subtable(struct cls_classifier *, struct cls_subtable *);
static void update_subtables_after_insertion(struct cls_classifier *,
struct cls_subtable *,
unsigned int new_priority);
static void update_subtables_after_removal(struct cls_classifier *,
struct cls_subtable *,
unsigned int del_priority);
static struct cls_match *find_match_wc(const struct cls_subtable *,
const struct flow *, struct trie_ctx *,
unsigned int n_tries,
struct flow_wildcards *);
static struct cls_match *find_equal(struct cls_subtable *,
const struct miniflow *, uint32_t hash);
static struct cls_match *insert_rule(struct cls_classifier *,
struct cls_subtable *, struct cls_rule *);
/* Iterates RULE over HEAD and all of the cls_rules on HEAD->list. */
#define FOR_EACH_RULE_IN_LIST(RULE, HEAD) \
for ((RULE) = (HEAD); (RULE) != NULL; (RULE) = next_rule_in_list(RULE))
#define FOR_EACH_RULE_IN_LIST_SAFE(RULE, NEXT, HEAD) \
for ((RULE) = (HEAD); \
(RULE) != NULL && ((NEXT) = next_rule_in_list(RULE), true); \
(RULE) = (NEXT))
static struct cls_match *next_rule_in_list__(struct cls_match *);
static struct cls_match *next_rule_in_list(struct cls_match *);
static unsigned int minimask_get_prefix_len(const struct minimask *,
const struct mf_field *);
static void trie_init(struct cls_classifier *, int trie_idx,
const struct mf_field *);
static unsigned int trie_lookup(const struct cls_trie *, const struct flow *,
unsigned int *checkbits);
static void trie_destroy(struct trie_node *);
static void trie_insert(struct cls_trie *, const struct cls_rule *, int mlen);
static void trie_remove(struct cls_trie *, const struct cls_rule *, int mlen);
static void mask_set_prefix_bits(struct flow_wildcards *, uint8_t be32ofs,
unsigned int nbits);
static bool mask_prefix_bits_set(const struct flow_wildcards *,
uint8_t be32ofs, unsigned int nbits);
static void
cls_subtable_cache_init(struct cls_subtable_cache *array)
{
memset(array, 0, sizeof *array);
}
static void
cls_subtable_cache_destroy(struct cls_subtable_cache *array)
{
free(array->subtables);
memset(array, 0, sizeof *array);
}
/* Array insertion. */
static void
cls_subtable_cache_push_back(struct cls_subtable_cache *array,
struct cls_subtable_entry a)
{
if (array->size == array->alloc_size) {
array->subtables = x2nrealloc(array->subtables, &array->alloc_size,
sizeof a);
}
array->subtables[array->size++] = a;
}
/* Only for rearranging entries in the same cache. */
static inline void
cls_subtable_cache_splice(struct cls_subtable_entry *to,
struct cls_subtable_entry *start,
struct cls_subtable_entry *end)
{
if (to > end) {
/* Same as splicing entries to (start) from [end, to). */
struct cls_subtable_entry *temp = to;
to = start; start = end; end = temp;
}
if (to < start) {
while (start != end) {
struct cls_subtable_entry temp = *start;
memmove(to + 1, to, (start - to) * sizeof *to);
*to = temp;
start++;
}
} /* Else nothing to be done. */
}
/* Array removal. */
static inline void
cls_subtable_cache_remove(struct cls_subtable_cache *array,
struct cls_subtable_entry *elem)
{
ssize_t size = (&array->subtables[array->size]
- (elem + 1)) * sizeof *elem;
if (size > 0) {
memmove(elem, elem + 1, size);
}
array->size--;
}
#define CLS_SUBTABLE_CACHE_FOR_EACH(SUBTABLE, ITER, ARRAY) \
for (ITER = (ARRAY)->subtables; \
ITER < &(ARRAY)->subtables[(ARRAY)->size] \
&& OVS_LIKELY(SUBTABLE = ITER->subtable); \
++ITER)
#define CLS_SUBTABLE_CACHE_FOR_EACH_CONTINUE(SUBTABLE, ITER, ARRAY) \
for (++ITER; \
ITER < &(ARRAY)->subtables[(ARRAY)->size] \
&& OVS_LIKELY(SUBTABLE = ITER->subtable); \
++ITER)
#define CLS_SUBTABLE_CACHE_FOR_EACH_REVERSE(SUBTABLE, ITER, ARRAY) \
for (ITER = &(ARRAY)->subtables[(ARRAY)->size]; \
ITER > (ARRAY)->subtables \
&& OVS_LIKELY(SUBTABLE = (--ITER)->subtable);)
/* flow/miniflow/minimask/minimatch utilities.
* These are only used by the classifier, so place them here to allow
* for better optimization. */
static inline uint64_t
miniflow_get_map_in_range(const struct miniflow *miniflow,
uint8_t start, uint8_t end, unsigned int *offset)
{
uint64_t map = miniflow->map;
*offset = 0;
if (start > 0) {
uint64_t msk = (UINT64_C(1) << start) - 1; /* 'start' LSBs set */
*offset = count_1bits(map & msk);
map &= ~msk;
}
if (end < FLOW_U32S) {
uint64_t msk = (UINT64_C(1) << end) - 1; /* 'end' LSBs set */
map &= msk;
}
return map;
}
/* Returns a hash value for the bits of 'flow' where there are 1-bits in
* 'mask', given 'basis'.
*
* The hash values returned by this function are the same as those returned by
* miniflow_hash_in_minimask(), only the form of the arguments differ. */
static inline uint32_t
flow_hash_in_minimask(const struct flow *flow, const struct minimask *mask,
uint32_t basis)
{
const uint32_t *flow_u32 = (const uint32_t *)flow;
const uint32_t *p = mask->masks.values;
uint32_t hash;
uint64_t map;
hash = basis;
for (map = mask->masks.map; map; map = zero_rightmost_1bit(map)) {
hash = mhash_add(hash, flow_u32[raw_ctz(map)] & *p++);
}
return mhash_finish(hash, (p - mask->masks.values) * 4);
}
/* Returns a hash value for the bits of 'flow' where there are 1-bits in
* 'mask', given 'basis'.
*
* The hash values returned by this function are the same as those returned by
* flow_hash_in_minimask(), only the form of the arguments differ. */
static inline uint32_t
miniflow_hash_in_minimask(const struct miniflow *flow,
const struct minimask *mask, uint32_t basis)
{
const uint32_t *p = mask->masks.values;
uint32_t hash = basis;
uint32_t flow_u32;
MINIFLOW_FOR_EACH_IN_MAP(flow_u32, flow, mask->masks.map) {
hash = mhash_add(hash, flow_u32 & *p++);
}
return mhash_finish(hash, (p - mask->masks.values) * 4);
}
/* Returns a hash value for the bits of range [start, end) in 'flow',
* where there are 1-bits in 'mask', given 'hash'.
*
* The hash values returned by this function are the same as those returned by
* minimatch_hash_range(), only the form of the arguments differ. */
static inline uint32_t
flow_hash_in_minimask_range(const struct flow *flow,
const struct minimask *mask,
uint8_t start, uint8_t end, uint32_t *basis)
{
const uint32_t *flow_u32 = (const uint32_t *)flow;
unsigned int offset;
uint64_t map = miniflow_get_map_in_range(&mask->masks, start, end,
&offset);
const uint32_t *p = mask->masks.values + offset;
uint32_t hash = *basis;
for (; map; map = zero_rightmost_1bit(map)) {
hash = mhash_add(hash, flow_u32[raw_ctz(map)] & *p++);
}
*basis = hash; /* Allow continuation from the unfinished value. */
return mhash_finish(hash, (p - mask->masks.values) * 4);
}
/* Fold minimask 'mask''s wildcard mask into 'wc's wildcard mask. */
static inline void
flow_wildcards_fold_minimask(struct flow_wildcards *wc,
const struct minimask *mask)
{
flow_union_with_miniflow(&wc->masks, &mask->masks);
}
/* Fold minimask 'mask''s wildcard mask into 'wc's wildcard mask
* in range [start, end). */
static inline void
flow_wildcards_fold_minimask_range(struct flow_wildcards *wc,
const struct minimask *mask,
uint8_t start, uint8_t end)
{
uint32_t *dst_u32 = (uint32_t *)&wc->masks;
unsigned int offset;
uint64_t map = miniflow_get_map_in_range(&mask->masks, start, end,
&offset);
const uint32_t *p = mask->masks.values + offset;
for (; map; map = zero_rightmost_1bit(map)) {
dst_u32[raw_ctz(map)] |= *p++;
}
}
/* Returns a hash value for 'flow', given 'basis'. */
static inline uint32_t
miniflow_hash(const struct miniflow *flow, uint32_t basis)
{
const uint32_t *p = flow->values;
uint32_t hash = basis;
uint64_t hash_map = 0;
uint64_t map;
for (map = flow->map; map; map = zero_rightmost_1bit(map)) {
if (*p) {
hash = mhash_add(hash, *p);
hash_map |= rightmost_1bit(map);
}
p++;
}
hash = mhash_add(hash, hash_map);
hash = mhash_add(hash, hash_map >> 32);
return mhash_finish(hash, p - flow->values);
}
/* Returns a hash value for 'mask', given 'basis'. */
static inline uint32_t
minimask_hash(const struct minimask *mask, uint32_t basis)
{
return miniflow_hash(&mask->masks, basis);
}
/* Returns a hash value for 'match', given 'basis'. */
static inline uint32_t
minimatch_hash(const struct minimatch *match, uint32_t basis)
{
return miniflow_hash(&match->flow, minimask_hash(&match->mask, basis));
}
/* Returns a hash value for the bits of range [start, end) in 'minimatch',
* given 'basis'.
*
* The hash values returned by this function are the same as those returned by
* flow_hash_in_minimask_range(), only the form of the arguments differ. */
static inline uint32_t
minimatch_hash_range(const struct minimatch *match, uint8_t start, uint8_t end,
uint32_t *basis)
{
unsigned int offset;
const uint32_t *p, *q;
uint32_t hash = *basis;
int n, i;
n = count_1bits(miniflow_get_map_in_range(&match->mask.masks, start, end,
&offset));
q = match->mask.masks.values + offset;
p = match->flow.values + offset;
for (i = 0; i < n; i++) {
hash = mhash_add(hash, p[i] & q[i]);
}
*basis = hash; /* Allow continuation from the unfinished value. */
return mhash_finish(hash, (offset + n) * 4);
}
/* cls_rule. */
/* Initializes 'rule' to match packets specified by 'match' at the given
* 'priority'. 'match' must satisfy the invariant described in the comment at
* the definition of struct match.
*
* The caller must eventually destroy 'rule' with cls_rule_destroy().
*
* (OpenFlow uses priorities between 0 and UINT16_MAX, inclusive, but
* internally Open vSwitch supports a wider range.) */
void
cls_rule_init(struct cls_rule *rule,
const struct match *match, unsigned int priority)
{
minimatch_init(&rule->match, match);
rule->priority = priority;
rule->cls_match = NULL;
}
/* Same as cls_rule_init() for initialization from a "struct minimatch". */
void
cls_rule_init_from_minimatch(struct cls_rule *rule,
const struct minimatch *match,
unsigned int priority)
{
minimatch_clone(&rule->match, match);
rule->priority = priority;
rule->cls_match = NULL;
}
/* Initializes 'dst' as a copy of 'src'.
*
* The caller must eventually destroy 'dst' with cls_rule_destroy(). */
void
cls_rule_clone(struct cls_rule *dst, const struct cls_rule *src)
{
minimatch_clone(&dst->match, &src->match);
dst->priority = src->priority;
dst->cls_match = NULL;
}
/* Initializes 'dst' with the data in 'src', destroying 'src'.
*
* The caller must eventually destroy 'dst' with cls_rule_destroy(). */
void
cls_rule_move(struct cls_rule *dst, struct cls_rule *src)
{
minimatch_move(&dst->match, &src->match);
dst->priority = src->priority;
dst->cls_match = NULL;
}
/* Frees memory referenced by 'rule'. Doesn't free 'rule' itself (it's
* normally embedded into a larger structure).
*
* ('rule' must not currently be in a classifier.) */
void
cls_rule_destroy(struct cls_rule *rule)
{
ovs_assert(!rule->cls_match);
minimatch_destroy(&rule->match);
}
/* Returns true if 'a' and 'b' match the same packets at the same priority,
* false if they differ in some way. */
bool
cls_rule_equal(const struct cls_rule *a, const struct cls_rule *b)
{
return a->priority == b->priority && minimatch_equal(&a->match, &b->match);
}
/* Returns a hash value for 'rule', folding in 'basis'. */
uint32_t
cls_rule_hash(const struct cls_rule *rule, uint32_t basis)
{
return minimatch_hash(&rule->match, hash_int(rule->priority, basis));
}
/* Appends a string describing 'rule' to 's'. */
void
cls_rule_format(const struct cls_rule *rule, struct ds *s)
{
minimatch_format(&rule->match, s, rule->priority);
}
/* Returns true if 'rule' matches every packet, false otherwise. */
bool
cls_rule_is_catchall(const struct cls_rule *rule)
{
return minimask_is_catchall(&rule->match.mask);
}
/* Initializes 'cls' as a classifier that initially contains no classification
* rules. */
void
classifier_init(struct classifier *cls_, const uint8_t *flow_segments)
{
struct cls_classifier *cls = xmalloc(sizeof *cls);
fat_rwlock_init(&cls_->rwlock);
cls_->cls = cls;
cls->n_rules = 0;
hmap_init(&cls->subtables);
cls_subtable_cache_init(&cls->subtables_priority);
hmap_init(&cls->partitions);
cls->n_flow_segments = 0;
if (flow_segments) {
while (cls->n_flow_segments < CLS_MAX_INDICES
&& *flow_segments < FLOW_U32S) {
cls->flow_segments[cls->n_flow_segments++] = *flow_segments++;
}
}
cls->n_tries = 0;
}
/* Destroys 'cls'. Rules within 'cls', if any, are not freed; this is the
* caller's responsibility. */
void
classifier_destroy(struct classifier *cls_)
{
if (cls_) {
struct cls_classifier *cls = cls_->cls;
struct cls_subtable *partition, *next_partition;
struct cls_subtable *subtable, *next_subtable;
int i;
fat_rwlock_destroy(&cls_->rwlock);
if (!cls) {
return;
}
for (i = 0; i < cls->n_tries; i++) {
trie_destroy(cls->tries[i].root);
}
HMAP_FOR_EACH_SAFE (subtable, next_subtable, hmap_node,
&cls->subtables) {
destroy_subtable(cls, subtable);
}
hmap_destroy(&cls->subtables);
HMAP_FOR_EACH_SAFE (partition, next_partition, hmap_node,
&cls->partitions) {
hmap_remove(&cls->partitions, &partition->hmap_node);
free(partition);
}
hmap_destroy(&cls->partitions);
cls_subtable_cache_destroy(&cls->subtables_priority);
free(cls);
}
}
/* We use uint64_t as a set for the fields below. */
BUILD_ASSERT_DECL(MFF_N_IDS <= 64);
/* Set the fields for which prefix lookup should be performed. */
void
classifier_set_prefix_fields(struct classifier *cls_,
const enum mf_field_id *trie_fields,
unsigned int n_fields)
{
struct cls_classifier *cls = cls_->cls;
uint64_t fields = 0;
int i, trie;
for (i = 0, trie = 0; i < n_fields && trie < CLS_MAX_TRIES; i++) {
const struct mf_field *field = mf_from_id(trie_fields[i]);
if (field->flow_be32ofs < 0 || field->n_bits % 32) {
/* Incompatible field. This is the only place where we
* enforce these requirements, but the rest of the trie code
* depends on the flow_be32ofs to be non-negative and the
* field length to be a multiple of 32 bits. */
continue;
}
if (fields & (UINT64_C(1) << trie_fields[i])) {
/* Duplicate field, there is no need to build more than
* one index for any one field. */
continue;
}
fields |= UINT64_C(1) << trie_fields[i];
if (trie >= cls->n_tries || field != cls->tries[trie].field) {
trie_init(cls, trie, field);
}
trie++;
}
/* Destroy the rest. */
for (i = trie; i < cls->n_tries; i++) {
trie_init(cls, i, NULL);
}
cls->n_tries = trie;
}
static void
trie_init(struct cls_classifier *cls, int trie_idx,
const struct mf_field *field)
{
struct cls_trie *trie = &cls->tries[trie_idx];
struct cls_subtable *subtable;
struct cls_subtable_entry *iter;
if (trie_idx < cls->n_tries) {
trie_destroy(trie->root);
}
trie->root = NULL;
trie->field = field;
/* Add existing rules to the trie. */
CLS_SUBTABLE_CACHE_FOR_EACH (subtable, iter, &cls->subtables_priority) {
unsigned int plen;
plen = field ? minimask_get_prefix_len(&subtable->mask, field) : 0;
/* Initialize subtable's prefix length on this field. */
subtable->trie_plen[trie_idx] = plen;
if (plen) {
struct cls_match *head;
HMAP_FOR_EACH (head, hmap_node, &subtable->rules) {
struct cls_match *match;
FOR_EACH_RULE_IN_LIST (match, head) {
trie_insert(trie, match->cls_rule, plen);
}
}
}
}
}
/* Returns true if 'cls' contains no classification rules, false otherwise. */
bool
classifier_is_empty(const struct classifier *cls)
{
return cls->cls->n_rules == 0;
}
/* Returns the number of rules in 'cls'. */
int
classifier_count(const struct classifier *cls)
{
return cls->cls->n_rules;
}
static uint32_t
hash_metadata(ovs_be64 metadata_)
{
uint64_t metadata = (OVS_FORCE uint64_t) metadata_;
return hash_uint64(metadata);
}
static struct cls_partition *
find_partition(const struct cls_classifier *cls, ovs_be64 metadata,
uint32_t hash)
{
struct cls_partition *partition;
HMAP_FOR_EACH_IN_BUCKET (partition, hmap_node, hash, &cls->partitions) {
if (partition->metadata == metadata) {
return partition;
}
}
return NULL;
}
static struct cls_partition *
create_partition(struct cls_classifier *cls, struct cls_subtable *subtable,
ovs_be64 metadata)
{
uint32_t hash = hash_metadata(metadata);
struct cls_partition *partition = find_partition(cls, metadata, hash);
if (!partition) {
partition = xmalloc(sizeof *partition);
partition->metadata = metadata;
partition->tags = 0;
tag_tracker_init(&partition->tracker);
hmap_insert(&cls->partitions, &partition->hmap_node, hash);
}
tag_tracker_add(&partition->tracker, &partition->tags, subtable->tag);
return partition;
}
/* Inserts 'rule' into 'cls'. Until 'rule' is removed from 'cls', the caller
* must not modify or free it.
*
* If 'cls' already contains an identical rule (including wildcards, values of
* fixed fields, and priority), replaces the old rule by 'rule' and returns the
* rule that was replaced. The caller takes ownership of the returned rule and
* is thus responsible for destroying it with cls_rule_destroy(), freeing the
* memory block in which it resides, etc., as necessary.
*
* Returns NULL if 'cls' does not contain a rule with an identical key, after
* inserting the new rule. In this case, no rules are displaced by the new
* rule, even rules that cannot have any effect because the new rule matches a
* superset of their flows and has higher priority. */
struct cls_rule *
classifier_replace(struct classifier *cls_, struct cls_rule *rule)
{
struct cls_classifier *cls = cls_->cls;
struct cls_match *old_rule;
struct cls_subtable *subtable;
subtable = find_subtable(cls, &rule->match.mask);
if (!subtable) {
subtable = insert_subtable(cls, &rule->match.mask);
}
old_rule = insert_rule(cls, subtable, rule);
if (!old_rule) {
int i;
rule->cls_match->partition = NULL;
if (minimask_get_metadata_mask(&rule->match.mask) == OVS_BE64_MAX) {
ovs_be64 metadata = miniflow_get_metadata(&rule->match.flow);
rule->cls_match->partition = create_partition(cls, subtable,
metadata);
}
subtable->n_rules++;
cls->n_rules++;
for (i = 0; i < cls->n_tries; i++) {
if (subtable->trie_plen[i]) {
trie_insert(&cls->tries[i], rule, subtable->trie_plen[i]);
}
}
return NULL;
} else {
struct cls_rule *old_cls_rule = old_rule->cls_rule;
rule->cls_match->partition = old_rule->partition;
old_cls_rule->cls_match = NULL;
free(old_rule);
return old_cls_rule;
}
}
/* Inserts 'rule' into 'cls'. Until 'rule' is removed from 'cls', the caller
* must not modify or free it.
*
* 'cls' must not contain an identical rule (including wildcards, values of
* fixed fields, and priority). Use classifier_find_rule_exactly() to find
* such a rule. */
void
classifier_insert(struct classifier *cls, struct cls_rule *rule)
{
struct cls_rule *displaced_rule = classifier_replace(cls, rule);
ovs_assert(!displaced_rule);
}
/* Removes 'rule' from 'cls'. It is the caller's responsibility to destroy
* 'rule' with cls_rule_destroy(), freeing the memory block in which 'rule'
* resides, etc., as necessary. */
void
classifier_remove(struct classifier *cls_, struct cls_rule *rule)
{
struct cls_classifier *cls = cls_->cls;
struct cls_partition *partition;
struct cls_match *cls_match = rule->cls_match;
struct cls_match *head;
struct cls_subtable *subtable;
int i;
ovs_assert(cls_match);
subtable = find_subtable(cls, &rule->match.mask);
ovs_assert(subtable);
for (i = 0; i < cls->n_tries; i++) {
if (subtable->trie_plen[i]) {
trie_remove(&cls->tries[i], rule, subtable->trie_plen[i]);
}
}
/* Remove rule node from indices. */
for (i = 0; i < subtable->n_indices; i++) {
hindex_remove(&subtable->indices[i], &cls_match->index_nodes[i]);
}
head = find_equal(subtable, &rule->match.flow, cls_match->hmap_node.hash);
if (head != cls_match) {
list_remove(&cls_match->list);
} else if (list_is_empty(&cls_match->list)) {
hmap_remove(&subtable->rules, &cls_match->hmap_node);
} else {
struct cls_match *next = CONTAINER_OF(cls_match->list.next,
struct cls_match, list);
list_remove(&cls_match->list);
hmap_replace(&subtable->rules, &cls_match->hmap_node,
&next->hmap_node);
}
partition = cls_match->partition;
if (partition) {
tag_tracker_subtract(&partition->tracker, &partition->tags,
subtable->tag);
if (!partition->tags) {
hmap_remove(&cls->partitions, &partition->hmap_node);
free(partition);
}
}
if (--subtable->n_rules == 0) {
destroy_subtable(cls, subtable);
} else {
update_subtables_after_removal(cls, subtable, cls_match->priority);
}
cls->n_rules--;
rule->cls_match = NULL;
free(cls_match);
}
/* Prefix tree context. Valid when 'lookup_done' is true. Can skip all
* subtables which have more than 'match_plen' bits in their corresponding
* field at offset 'be32ofs'. If skipped, 'maskbits' prefix bits should be
* unwildcarded to quarantee datapath flow matches only packets it should. */
struct trie_ctx {
const struct cls_trie *trie;
bool lookup_done; /* Status of the lookup. */
uint8_t be32ofs; /* U32 offset of the field in question. */
unsigned int match_plen; /* Longest prefix than could possibly match. */
unsigned int maskbits; /* Prefix length needed to avoid false matches. */
};
static void
trie_ctx_init(struct trie_ctx *ctx, const struct cls_trie *trie)
{
ctx->trie = trie;
ctx->be32ofs = trie->field->flow_be32ofs;
ctx->lookup_done = false;
}
static inline void
lookahead_subtable(const struct cls_subtable_entry *subtables)
{
ovs_prefetch_range(subtables->subtable, sizeof *subtables->subtable);
ovs_prefetch_range(subtables->mask_values, 1);
}
/* Finds and returns the highest-priority rule in 'cls' that matches 'flow'.
* Returns a null pointer if no rules in 'cls' match 'flow'. If multiple rules
* of equal priority match 'flow', returns one arbitrarily.
*
* If a rule is found and 'wc' is non-null, bitwise-OR's 'wc' with the
* set of bits that were significant in the lookup. At some point
* earlier, 'wc' should have been initialized (e.g., by
* flow_wildcards_init_catchall()). */
struct cls_rule *
classifier_lookup(const struct classifier *cls_, const struct flow *flow,
struct flow_wildcards *wc)
{
struct cls_classifier *cls = cls_->cls;
const struct cls_partition *partition;
tag_type tags;
struct cls_match *best;
struct trie_ctx trie_ctx[CLS_MAX_TRIES];
int i;
struct cls_subtable_entry *subtables = cls->subtables_priority.subtables;
int n_subtables = cls->subtables_priority.size;
int64_t best_priority = -1;
/* Prefetch the subtables array. */
ovs_prefetch_range(subtables, n_subtables * sizeof *subtables);
/* Determine 'tags' such that, if 'subtable->tag' doesn't intersect them,
* then 'flow' cannot possibly match in 'subtable':
*
* - If flow->metadata maps to a given 'partition', then we can use
* 'tags' for 'partition->tags'.
*
* - If flow->metadata has no partition, then no rule in 'cls' has an
* exact-match for flow->metadata. That means that we don't need to
* search any subtable that includes flow->metadata in its mask.
*
* In either case, we always need to search any cls_subtables that do not
* include flow->metadata in its mask. One way to do that would be to
* check the "cls_subtable"s explicitly for that, but that would require an
* extra branch per subtable. Instead, we mark such a cls_subtable's
* 'tags' as TAG_ALL and make sure that 'tags' is never empty. This means
* that 'tags' always intersects such a cls_subtable's 'tags', so we don't
* need a special case.
*/
partition = (hmap_is_empty(&cls->partitions)
? NULL
: find_partition(cls, flow->metadata,
hash_metadata(flow->metadata)));
tags = partition ? partition->tags : TAG_ARBITRARY;
/* Initialize trie contexts for match_find_wc(). */
for (i = 0; i < cls->n_tries; i++) {
trie_ctx_init(&trie_ctx[i], &cls->tries[i]);
}
/* Prefetch the first subtables. */
if (n_subtables > 1) {
lookahead_subtable(subtables);
lookahead_subtable(subtables + 1);
}
best = NULL;
for (i = 0; OVS_LIKELY(i < n_subtables); i++) {
struct cls_match *rule;
if ((int64_t)subtables[i].max_priority <= best_priority) {
/* Subtables are in descending priority order,
* can not find anything better. */
break;
}
/* Prefetch a forthcoming subtable. */
if (i + 2 < n_subtables) {
lookahead_subtable(&subtables[i + 2]);
}
if (!tag_intersects(tags, subtables[i].tag)) {
continue;
}
rule = find_match_wc(subtables[i].subtable, flow, trie_ctx,
cls->n_tries, wc);
if (rule && (int64_t)rule->priority > best_priority) {
best_priority = (int64_t)rule->priority;
best = rule;
}
}
return best ? best->cls_rule : NULL;
}
/* Returns true if 'target' satisifies 'match', that is, if each bit for which
* 'match' specifies a particular value has the correct value in 'target'. */
static bool
minimatch_matches_miniflow(const struct minimatch *match,
const struct miniflow *target)
{
const uint32_t *flowp = (const uint32_t *)match->flow.values;
const uint32_t *maskp = (const uint32_t *)match->mask.masks.values;
uint32_t target_u32;
MINIFLOW_FOR_EACH_IN_MAP(target_u32, target, match->mask.masks.map) {
if ((*flowp++ ^ target_u32) & *maskp++) {
return false;
}
}
return true;
}
static inline struct cls_match *
find_match_miniflow(const struct cls_subtable *subtable,
const struct miniflow *flow,
uint32_t hash)
{
struct cls_match *rule;
HMAP_FOR_EACH_WITH_HASH (rule, hmap_node, hash, &subtable->rules) {
if (minimatch_matches_miniflow(&rule->match, flow)) {
return rule;
}
}
return NULL;
}
/* Finds and returns the highest-priority rule in 'cls' that matches
* 'miniflow'. Returns a null pointer if no rules in 'cls' match 'flow'.
* If multiple rules of equal priority match 'flow', returns one arbitrarily.
*
* This function is optimized for the userspace datapath, which only ever has
* one priority value for it's flows!
*/
struct cls_rule *classifier_lookup_miniflow_first(const struct classifier *cls_,
const struct miniflow *flow)
{
struct cls_classifier *cls = cls_->cls;
struct cls_subtable *subtable;
struct cls_subtable_entry *iter;
CLS_SUBTABLE_CACHE_FOR_EACH (subtable, iter, &cls->subtables_priority) {
struct cls_match *rule;
rule = find_match_miniflow(subtable, flow,
miniflow_hash_in_minimask(flow,
&subtable->mask,
0));
if (rule) {
return rule->cls_rule;
}
}
return NULL;
}
/* Finds and returns a rule in 'cls' with exactly the same priority and
* matching criteria as 'target'. Returns a null pointer if 'cls' doesn't
* contain an exact match. */
struct cls_rule *
classifier_find_rule_exactly(const struct classifier *cls_,
const struct cls_rule *target)
{
struct cls_classifier *cls = cls_->cls;
struct cls_match *head, *rule;
struct cls_subtable *subtable;
subtable = find_subtable(cls, &target->match.mask);
if (!subtable) {
return NULL;
}
/* Skip if there is no hope. */
if (target->priority > subtable->max_priority) {
return NULL;
}
head = find_equal(subtable, &target->match.flow,
miniflow_hash_in_minimask(&target->match.flow,
&target->match.mask, 0));
FOR_EACH_RULE_IN_LIST (rule, head) {
if (target->priority >= rule->priority) {
return target->priority == rule->priority ? rule->cls_rule : NULL;
}
}
return NULL;
}
/* Finds and returns a rule in 'cls' with priority 'priority' and exactly the
* same matching criteria as 'target'. Returns a null pointer if 'cls' doesn't
* contain an exact match. */
struct cls_rule *
classifier_find_match_exactly(const struct classifier *cls,
const struct match *target,
unsigned int priority)
{
struct cls_rule *retval;
struct cls_rule cr;
cls_rule_init(&cr, target, priority);
retval = classifier_find_rule_exactly(cls, &cr);
cls_rule_destroy(&cr);
return retval;
}
/* Checks if 'target' would overlap any other rule in 'cls'. Two rules are
* considered to overlap if both rules have the same priority and a packet
* could match both. */
bool
classifier_rule_overlaps(const struct classifier *cls_,
const struct cls_rule *target)
{
struct cls_classifier *cls = cls_->cls;
struct cls_subtable *subtable;
struct cls_subtable_entry *iter;
/* Iterate subtables in the descending max priority order. */
CLS_SUBTABLE_CACHE_FOR_EACH (subtable, iter, &cls->subtables_priority) {
uint32_t storage[FLOW_U32S];
struct minimask mask;
struct cls_match *head;
if (target->priority > iter->max_priority) {
break; /* Can skip this and the rest of the subtables. */
}
minimask_combine(&mask, &target->match.mask, &subtable->mask, storage);
HMAP_FOR_EACH (head, hmap_node, &subtable->rules) {
struct cls_match *rule;
FOR_EACH_RULE_IN_LIST (rule, head) {
if (rule->priority < target->priority) {
break; /* Rules in descending priority order. */
}
if (rule->priority == target->priority
&& miniflow_equal_in_minimask(&target->match.flow,
&rule->match.flow, &mask)) {
return true;
}
}
}
}
return false;
}
/* Returns true if 'rule' exactly matches 'criteria' or if 'rule' is more
* specific than 'criteria'. That is, 'rule' matches 'criteria' and this
* function returns true if, for every field:
*
* - 'criteria' and 'rule' specify the same (non-wildcarded) value for the
* field, or
*
* - 'criteria' wildcards the field,
*
* Conversely, 'rule' does not match 'criteria' and this function returns false
* if, for at least one field:
*
* - 'criteria' and 'rule' specify different values for the field, or
*
* - 'criteria' specifies a value for the field but 'rule' wildcards it.
*
* Equivalently, the truth table for whether a field matches is:
*
* rule
*
* c wildcard exact
* r +---------+---------+
* i wild | yes | yes |
* t card | | |
* e +---------+---------+
* r exact | no |if values|
* i | |are equal|
* a +---------+---------+
*
* This is the matching rule used by OpenFlow 1.0 non-strict OFPT_FLOW_MOD
* commands and by OpenFlow 1.0 aggregate and flow stats.
*
* Ignores rule->priority. */
bool
cls_rule_is_loose_match(const struct cls_rule *rule,
const struct minimatch *criteria)
{
return (!minimask_has_extra(&rule->match.mask, &criteria->mask)
&& miniflow_equal_in_minimask(&rule->match.flow, &criteria->flow,
&criteria->mask));
}
/* Iteration. */
static bool
rule_matches(const struct cls_match *rule, const struct cls_rule *target)
{
return (!target
|| miniflow_equal_in_minimask(&rule->match.flow,
&target->match.flow,
&target->match.mask));
}
static struct cls_match *
search_subtable(const struct cls_subtable *subtable,
const struct cls_rule *target)
{
if (!target || !minimask_has_extra(&subtable->mask, &target->match.mask)) {
struct cls_match *rule;
HMAP_FOR_EACH (rule, hmap_node, &subtable->rules) {
if (rule_matches(rule, target)) {
return rule;
}
}
}
return NULL;
}
/* Initializes 'cursor' for iterating through rules in 'cls':
*
* - If 'target' is null, the cursor will visit every rule in 'cls'.
*
* - If 'target' is nonnull, the cursor will visit each 'rule' in 'cls'
* such that cls_rule_is_loose_match(rule, target) returns true.
*
* Ignores target->priority. */
void
cls_cursor_init(struct cls_cursor *cursor, const struct classifier *cls,
const struct cls_rule *target)
{
cursor->cls = cls->cls;
cursor->target = target && !cls_rule_is_catchall(target) ? target : NULL;
}
/* Returns the first matching cls_rule in 'cursor''s iteration, or a null
* pointer if there are no matches. */
struct cls_rule *
cls_cursor_first(struct cls_cursor *cursor)
{
struct cls_subtable *subtable;
HMAP_FOR_EACH (subtable, hmap_node, &cursor->cls->subtables) {
struct cls_match *rule = search_subtable(subtable, cursor->target);
if (rule) {
cursor->subtable = subtable;
return rule->cls_rule;
}
}
return NULL;
}
/* Returns the next matching cls_rule in 'cursor''s iteration, or a null
* pointer if there are no more matches. */
struct cls_rule *
cls_cursor_next(struct cls_cursor *cursor, const struct cls_rule *rule_)
{
struct cls_match *rule = CONST_CAST(struct cls_match *, rule_->cls_match);
const struct cls_subtable *subtable;
struct cls_match *next;
next = next_rule_in_list__(rule);
if (next->priority < rule->priority) {
return next->cls_rule;
}
/* 'next' is the head of the list, that is, the rule that is included in
* the subtable's hmap. (This is important when the classifier contains
* rules that differ only in priority.) */
rule = next;
HMAP_FOR_EACH_CONTINUE (rule, hmap_node, &cursor->subtable->rules) {
if (rule_matches(rule, cursor->target)) {
return rule->cls_rule;
}
}
subtable = cursor->subtable;
HMAP_FOR_EACH_CONTINUE (subtable, hmap_node, &cursor->cls->subtables) {
rule = search_subtable(subtable, cursor->target);
if (rule) {
cursor->subtable = subtable;
return rule->cls_rule;
}
}
return NULL;
}
static struct cls_subtable *
find_subtable(const struct cls_classifier *cls, const struct minimask *mask)
{
struct cls_subtable *subtable;
HMAP_FOR_EACH_IN_BUCKET (subtable, hmap_node, minimask_hash(mask, 0),
&cls->subtables) {
if (minimask_equal(mask, &subtable->mask)) {
return subtable;
}
}
return NULL;
}
static struct cls_subtable *
insert_subtable(struct cls_classifier *cls, const struct minimask *mask)
{
uint32_t hash = minimask_hash(mask, 0);
struct cls_subtable *subtable;
int i, index = 0;
struct flow_wildcards old, new;
uint8_t prev;
struct cls_subtable_entry elem;
subtable = xzalloc(sizeof *subtable);
hmap_init(&subtable->rules);
minimask_clone(&subtable->mask, mask);
/* Init indices for segmented lookup, if any. */
flow_wildcards_init_catchall(&new);
old = new;
prev = 0;
for (i = 0; i < cls->n_flow_segments; i++) {
flow_wildcards_fold_minimask_range(&new, mask, prev,
cls->flow_segments[i]);
/* Add an index if it adds mask bits. */
if (!flow_wildcards_equal(&new, &old)) {
hindex_init(&subtable->indices[index]);
subtable->index_ofs[index] = cls->flow_segments[i];
index++;
old = new;
}
prev = cls->flow_segments[i];
}
/* Check if the rest of the subtable's mask adds any bits,
* and remove the last index if it doesn't. */
if (index > 0) {
flow_wildcards_fold_minimask_range(&new, mask, prev, FLOW_U32S);
if (flow_wildcards_equal(&new, &old)) {
--index;
subtable->index_ofs[index] = 0;
hindex_destroy(&subtable->indices[index]);
}
}
subtable->n_indices = index;
subtable->tag = (minimask_get_metadata_mask(mask) == OVS_BE64_MAX
? tag_create_deterministic(hash)
: TAG_ALL);
for (i = 0; i < cls->n_tries; i++) {
subtable->trie_plen[i] = minimask_get_prefix_len(mask,
cls->tries[i].field);
}
hmap_insert(&cls->subtables, &subtable->hmap_node, hash);
elem.subtable = subtable;
elem.mask_values = subtable->mask.masks.values;
elem.tag = subtable->tag;
elem.max_priority = subtable->max_priority;
cls_subtable_cache_push_back(&cls->subtables_priority, elem);
return subtable;
}
static void
destroy_subtable(struct cls_classifier *cls, struct cls_subtable *subtable)
{
int i;
struct cls_subtable *table = NULL;
struct cls_subtable_entry *iter;
CLS_SUBTABLE_CACHE_FOR_EACH (table, iter, &cls->subtables_priority) {
if (table == subtable) {
cls_subtable_cache_remove(&cls->subtables_priority, iter);
break;
}
}
for (i = 0; i < subtable->n_indices; i++) {
hindex_destroy(&subtable->indices[i]);
}
minimask_destroy(&subtable->mask);
hmap_remove(&cls->subtables, &subtable->hmap_node);
hmap_destroy(&subtable->rules);
free(subtable);
}
/* This function performs the following updates for 'subtable' in 'cls'
* following the addition of a new rule with priority 'new_priority' to
* 'subtable':
*
* - Update 'subtable->max_priority' and 'subtable->max_count' if necessary.
*
* - Update 'subtable''s position in 'cls->subtables_priority' if necessary.
*
* This function should only be called after adding a new rule, not after
* replacing a rule by an identical one or modifying a rule in-place. */
static void
update_subtables_after_insertion(struct cls_classifier *cls,
struct cls_subtable *subtable,
unsigned int new_priority)
{
if (new_priority == subtable->max_priority) {
++subtable->max_count;
} else if (new_priority > subtable->max_priority) {
struct cls_subtable *table;
struct cls_subtable_entry *iter, *subtable_iter = NULL;
subtable->max_priority = new_priority;
subtable->max_count = 1;
/* Possibly move 'subtable' earlier in the priority list. If we break
* out of the loop, then 'subtable_iter' should be moved just before
* 'iter'. If the loop terminates normally, then 'iter' will be the
* first list element and we'll move subtable just before that
* (e.g. to the front of the list). */
CLS_SUBTABLE_CACHE_FOR_EACH_REVERSE (table, iter, &cls->subtables_priority) {
if (table == subtable) {
subtable_iter = iter; /* Locate the subtable as we go. */
iter->max_priority = new_priority;
} else if (table->max_priority >= new_priority) {
ovs_assert(subtable_iter != NULL);
iter++;
break;
}
}
/* Move 'subtable' just before 'iter' (unless it's already there). */
if (iter != subtable_iter) {
cls_subtable_cache_splice(iter, subtable_iter, subtable_iter + 1);
}
}
}
/* This function performs the following updates for 'subtable' in 'cls'
* following the deletion of a rule with priority 'del_priority' from
* 'subtable':
*
* - Update 'subtable->max_priority' and 'subtable->max_count' if necessary.
*
* - Update 'subtable''s position in 'cls->subtables_priority' if necessary.
*
* This function should only be called after removing a rule, not after
* replacing a rule by an identical one or modifying a rule in-place. */
static void
update_subtables_after_removal(struct cls_classifier *cls,
struct cls_subtable *subtable,
unsigned int del_priority)
{
if (del_priority == subtable->max_priority && --subtable->max_count == 0) {
struct cls_match *head;
struct cls_subtable *table;
struct cls_subtable_entry *iter, *subtable_iter = NULL;
subtable->max_priority = 0;
HMAP_FOR_EACH (head, hmap_node, &subtable->rules) {
if (head->priority > subtable->max_priority) {
subtable->max_priority = head->priority;
subtable->max_count = 1;
} else if (head->priority == subtable->max_priority) {
++subtable->max_count;
}
}
/* Possibly move 'subtable' later in the priority list. If we break
* out of the loop, then 'subtable' should be moved just before that
* 'iter'. If the loop terminates normally, then 'iter' will be the
* list head and we'll move subtable just before that (e.g. to the back
* of the list). */
CLS_SUBTABLE_CACHE_FOR_EACH (table, iter, &cls->subtables_priority) {
if (table == subtable) {
subtable_iter = iter; /* Locate the subtable as we go. */
iter->max_priority = subtable->max_priority;
} else if (table->max_priority <= subtable->max_priority) {
ovs_assert(subtable_iter != NULL);
break;
}
}
/* Move 'subtable' just before 'iter' (unless it's already there). */
if (iter != subtable_iter) {
cls_subtable_cache_splice(iter, subtable_iter, subtable_iter + 1);
}
}
}
struct range {
uint8_t start;
uint8_t end;
};
/* Return 'true' if can skip rest of the subtable based on the prefix trie
* lookup results. */
static inline bool
check_tries(struct trie_ctx trie_ctx[CLS_MAX_TRIES], unsigned int n_tries,
const unsigned int field_plen[CLS_MAX_TRIES],
const struct range ofs, const struct flow *flow,
struct flow_wildcards *wc)
{
int j;
/* Check if we could avoid fully unwildcarding the next level of
* fields using the prefix tries. The trie checks are done only as
* needed to avoid folding in additional bits to the wildcards mask. */
for (j = 0; j < n_tries; j++) {
/* Is the trie field relevant for this subtable? */
if (field_plen[j]) {
struct trie_ctx *ctx = &trie_ctx[j];
uint8_t be32ofs = ctx->be32ofs;
/* Is the trie field within the current range of fields? */
if (be32ofs >= ofs.start && be32ofs < ofs.end) {
/* On-demand trie lookup. */
if (!ctx->lookup_done) {
ctx->match_plen = trie_lookup(ctx->trie, flow,
&ctx->maskbits);
ctx->lookup_done = true;
}
/* Possible to skip the rest of the subtable if subtable's
* prefix on the field is longer than what is known to match
* based on the trie lookup. */
if (field_plen[j] > ctx->match_plen) {
/* RFC: We want the trie lookup to never result in
* unwildcarding any bits that would not be unwildcarded
* otherwise. Since the trie is shared by the whole
* classifier, it is possible that the 'maskbits' contain
* bits that are irrelevant for the partition of the
* classifier relevant for the current flow. */
/* Can skip if the field is already unwildcarded. */
if (mask_prefix_bits_set(wc, be32ofs, ctx->maskbits)) {
return true;
}
/* Check that the trie result will not unwildcard more bits
* than this stage will. */
if (ctx->maskbits <= field_plen[j]) {
/* Unwildcard the bits and skip the rest. */
mask_set_prefix_bits(wc, be32ofs, ctx->maskbits);
/* Note: Prerequisite already unwildcarded, as the only
* prerequisite of the supported trie lookup fields is
* the ethertype, which is currently always
* unwildcarded.
*/
return true;
}
}
}
}
}
return false;
}
static inline struct cls_match *
find_match(const struct cls_subtable *subtable, const struct flow *flow,
uint32_t hash)
{
struct cls_match *rule;
HMAP_FOR_EACH_WITH_HASH (rule, hmap_node, hash, &subtable->rules) {
if (minimatch_matches_flow(&rule->match, flow)) {
return rule;
}
}
return NULL;
}
static struct cls_match *
find_match_wc(const struct cls_subtable *subtable, const struct flow *flow,
struct trie_ctx trie_ctx[CLS_MAX_TRIES], unsigned int n_tries,
struct flow_wildcards *wc)
{
uint32_t basis = 0, hash;
struct cls_match *rule = NULL;
int i;
struct range ofs;
if (OVS_UNLIKELY(!wc)) {
return find_match(subtable, flow,
flow_hash_in_minimask(flow, &subtable->mask, 0));
}
ofs.start = 0;
/* Try to finish early by checking fields in segments. */
for (i = 0; i < subtable->n_indices; i++) {
struct hindex_node *inode;
ofs.end = subtable->index_ofs[i];
if (check_tries(trie_ctx, n_tries, subtable->trie_plen, ofs, flow,
wc)) {
goto range_out;
}
hash = flow_hash_in_minimask_range(flow, &subtable->mask, ofs.start,
ofs.end, &basis);
ofs.start = ofs.end;
inode = hindex_node_with_hash(&subtable->indices[i], hash);
if (!inode) {
/* No match, can stop immediately, but must fold in the mask
* covered so far. */
goto range_out;
}
/* If we have narrowed down to a single rule already, check whether
* that rule matches. If it does match, then we're done. If it does
* not match, then we know that we will never get a match, but we do
* not yet know how many wildcards we need to fold into 'wc' so we
* continue iterating through indices to find that out. (We won't
* waste time calling minimatch_matches_flow() again because we've set
* 'rule' nonnull.)
*
* This check shows a measurable benefit with non-trivial flow tables.
*
* (Rare) hash collisions may cause us to miss the opportunity for this
* optimization. */
if (!inode->s && !rule) {
ASSIGN_CONTAINER(rule, inode - i, index_nodes);
if (minimatch_matches_flow(&rule->match, flow)) {
goto out;
}
}
}
ofs.end = FLOW_U32S;
/* Trie check for the final range. */
if (check_tries(trie_ctx, n_tries, subtable->trie_plen, ofs, flow, wc)) {
goto range_out;
}
if (!rule) {
/* Multiple potential matches exist, look for one. */
hash = flow_hash_in_minimask_range(flow, &subtable->mask, ofs.start,
ofs.end, &basis);
rule = find_match(subtable, flow, hash);
} else {
/* We already narrowed the matching candidates down to just 'rule',
* but it didn't match. */
rule = NULL;
}
out:
/* Must unwildcard all the fields, as they were looked at. */
flow_wildcards_fold_minimask(wc, &subtable->mask);
return rule;
range_out:
/* Must unwildcard the fields looked up so far, if any. */
if (ofs.start) {
flow_wildcards_fold_minimask_range(wc, &subtable->mask, 0, ofs.start);
}
return NULL;
}
static struct cls_match *
find_equal(struct cls_subtable *subtable, const struct miniflow *flow,
uint32_t hash)
{
struct cls_match *head;
HMAP_FOR_EACH_WITH_HASH (head, hmap_node, hash, &subtable->rules) {
if (miniflow_equal(&head->match.flow, flow)) {
return head;
}
}
return NULL;
}
static struct cls_match *
insert_rule(struct cls_classifier *cls, struct cls_subtable *subtable,
struct cls_rule *new)
{
struct cls_match *cls_match = cls_match_alloc(new);
struct cls_match *head;
struct cls_match *old = NULL;
int i;
uint32_t basis = 0, hash;
uint8_t prev_be32ofs = 0;
/* Add new node to segment indices. */
for (i = 0; i < subtable->n_indices; i++) {
hash = minimatch_hash_range(&new->match, prev_be32ofs,
subtable->index_ofs[i], &basis);
hindex_insert(&subtable->indices[i], &cls_match->index_nodes[i], hash);
prev_be32ofs = subtable->index_ofs[i];
}
hash = minimatch_hash_range(&new->match, prev_be32ofs, FLOW_U32S, &basis);
head = find_equal(subtable, &new->match.flow, hash);
if (!head) {
hmap_insert(&subtable->rules, &cls_match->hmap_node, hash);
list_init(&cls_match->list);
goto out;
} else {
/* Scan the list for the insertion point that will keep the list in
* order of decreasing priority. */
struct cls_match *rule;
cls_match->hmap_node.hash = hash; /* Otherwise done by hmap_insert. */
FOR_EACH_RULE_IN_LIST (rule, head) {
if (cls_match->priority >= rule->priority) {
if (rule == head) {
/* 'new' is the new highest-priority flow in the list. */
hmap_replace(&subtable->rules,
&rule->hmap_node, &cls_match->hmap_node);
}
if (cls_match->priority == rule->priority) {
list_replace(&cls_match->list, &rule->list);
old = rule;
goto out;
} else {
list_insert(&rule->list, &cls_match->list);
goto out;
}
}
}
/* Insert 'new' at the end of the list. */
list_push_back(&head->list, &cls_match->list);
}
out:
if (!old) {
update_subtables_after_insertion(cls, subtable, cls_match->priority);
} else {
/* Remove old node from indices. */
for (i = 0; i < subtable->n_indices; i++) {
hindex_remove(&subtable->indices[i], &old->index_nodes[i]);
}
}
return old;
}
static struct cls_match *
next_rule_in_list__(struct cls_match *rule)
{
struct cls_match *next = OBJECT_CONTAINING(rule->list.next, next, list);
return next;
}
static struct cls_match *
next_rule_in_list(struct cls_match *rule)
{
struct cls_match *next = next_rule_in_list__(rule);
return next->priority < rule->priority ? next : NULL;
}
/* A longest-prefix match tree. */
struct trie_node {
uint32_t prefix; /* Prefix bits for this node, MSB first. */
uint8_t nbits; /* Never zero, except for the root node. */
unsigned int n_rules; /* Number of rules that have this prefix. */
struct trie_node *edges[2]; /* Both NULL if leaf. */
};
/* Max bits per node. Must fit in struct trie_node's 'prefix'.
* Also tested with 16, 8, and 5 to stress the implementation. */
#define TRIE_PREFIX_BITS 32
/* Return at least 'plen' bits of the 'prefix', starting at bit offset 'ofs'.
* Prefixes are in the network byte order, and the offset 0 corresponds to
* the most significant bit of the first byte. The offset can be read as
* "how many bits to skip from the start of the prefix starting at 'pr'". */
static uint32_t
raw_get_prefix(const ovs_be32 pr[], unsigned int ofs, unsigned int plen)
{
uint32_t prefix;
pr += ofs / 32; /* Where to start. */
ofs %= 32; /* How many bits to skip at 'pr'. */
prefix = ntohl(*pr) << ofs; /* Get the first 32 - ofs bits. */
if (plen > 32 - ofs) { /* Need more than we have already? */
prefix |= ntohl(*++pr) >> (32 - ofs);
}
/* Return with possible unwanted bits at the end. */
return prefix;
}
/* Return min(TRIE_PREFIX_BITS, plen) bits of the 'prefix', starting at bit
* offset 'ofs'. Prefixes are in the network byte order, and the offset 0
* corresponds to the most significant bit of the first byte. The offset can
* be read as "how many bits to skip from the start of the prefix starting at
* 'pr'". */
static uint32_t
trie_get_prefix(const ovs_be32 pr[], unsigned int ofs, unsigned int plen)
{
if (!plen) {
return 0;
}
if (plen > TRIE_PREFIX_BITS) {
plen = TRIE_PREFIX_BITS; /* Get at most TRIE_PREFIX_BITS. */
}
/* Return with unwanted bits cleared. */
return raw_get_prefix(pr, ofs, plen) & ~0u << (32 - plen);
}
/* Return the number of equal bits in 'nbits' of 'prefix's MSBs and a 'value'
* starting at "MSB 0"-based offset 'ofs'. */
static unsigned int
prefix_equal_bits(uint32_t prefix, unsigned int nbits, const ovs_be32 value[],
unsigned int ofs)
{
uint64_t diff = prefix ^ raw_get_prefix(value, ofs, nbits);
/* Set the bit after the relevant bits to limit the result. */
return raw_clz64(diff << 32 | UINT64_C(1) << (63 - nbits));
}
/* Return the number of equal bits in 'node' prefix and a 'prefix' of length
* 'plen', starting at "MSB 0"-based offset 'ofs'. */
static unsigned int
trie_prefix_equal_bits(const struct trie_node *node, const ovs_be32 prefix[],
unsigned int ofs, unsigned int plen)
{
return prefix_equal_bits(node->prefix, MIN(node->nbits, plen - ofs),
prefix, ofs);
}
/* Return the bit at ("MSB 0"-based) offset 'ofs' as an int. 'ofs' can
* be greater than 31. */
static unsigned int
be_get_bit_at(const ovs_be32 value[], unsigned int ofs)
{
return (((const uint8_t *)value)[ofs / 8] >> (7 - ofs % 8)) & 1u;
}
/* Return the bit at ("MSB 0"-based) offset 'ofs' as an int. 'ofs' must
* be between 0 and 31, inclusive. */
static unsigned int
get_bit_at(const uint32_t prefix, unsigned int ofs)
{
return (prefix >> (31 - ofs)) & 1u;
}
/* Create new branch. */
static struct trie_node *
trie_branch_create(const ovs_be32 *prefix, unsigned int ofs, unsigned int plen,
unsigned int n_rules)
{
struct trie_node *node = xmalloc(sizeof *node);
node->prefix = trie_get_prefix(prefix, ofs, plen);
if (plen <= TRIE_PREFIX_BITS) {
node->nbits = plen;
node->edges[0] = NULL;
node->edges[1] = NULL;
node->n_rules = n_rules;
} else { /* Need intermediate nodes. */
struct trie_node *subnode = trie_branch_create(prefix,
ofs + TRIE_PREFIX_BITS,
plen - TRIE_PREFIX_BITS,
n_rules);
int bit = get_bit_at(subnode->prefix, 0);
node->nbits = TRIE_PREFIX_BITS;
node->edges[bit] = subnode;
node->edges[!bit] = NULL;
node->n_rules = 0;
}
return node;
}
static void
trie_node_destroy(struct trie_node *node)
{
free(node);
}
static void
trie_destroy(struct trie_node *node)
{
if (node) {
trie_destroy(node->edges[0]);
trie_destroy(node->edges[1]);
free(node);
}
}
static bool
trie_is_leaf(const struct trie_node *trie)
{
return !trie->edges[0] && !trie->edges[1]; /* No children. */
}
static void
mask_set_prefix_bits(struct flow_wildcards *wc, uint8_t be32ofs,
unsigned int nbits)
{
ovs_be32 *mask = &((ovs_be32 *)&wc->masks)[be32ofs];
unsigned int i;
for (i = 0; i < nbits / 32; i++) {
mask[i] = OVS_BE32_MAX;
}
if (nbits % 32) {
mask[i] |= htonl(~0u << (32 - nbits % 32));
}
}
static bool
mask_prefix_bits_set(const struct flow_wildcards *wc, uint8_t be32ofs,
unsigned int nbits)
{
ovs_be32 *mask = &((ovs_be32 *)&wc->masks)[be32ofs];
unsigned int i;
ovs_be32 zeroes = 0;
for (i = 0; i < nbits / 32; i++) {
zeroes |= ~mask[i];
}
if (nbits % 32) {
zeroes |= ~mask[i] & htonl(~0u << (32 - nbits % 32));
}
return !zeroes; /* All 'nbits' bits set. */
}
static struct trie_node **
trie_next_edge(struct trie_node *node, const ovs_be32 value[],
unsigned int ofs)
{
return node->edges + be_get_bit_at(value, ofs);
}
static const struct trie_node *
trie_next_node(const struct trie_node *node, const ovs_be32 value[],
unsigned int ofs)
{
return node->edges[be_get_bit_at(value, ofs)];
}
/* Return the prefix mask length necessary to find the longest-prefix match for
* the '*value' in the prefix tree 'node'.
* '*checkbits' is set to the number of bits in the prefix mask necessary to
* determine a mismatch, in case there are longer prefixes in the tree below
* the one that matched.
*/
static unsigned int
trie_lookup_value(const struct trie_node *node, const ovs_be32 value[],
unsigned int *checkbits)
{
unsigned int plen = 0, match_len = 0;
const struct trie_node *prev = NULL;
for (; node; prev = node, node = trie_next_node(node, value, plen)) {
unsigned int eqbits;
/* Check if this edge can be followed. */
eqbits = prefix_equal_bits(node->prefix, node->nbits, value, plen);
plen += eqbits;
if (eqbits < node->nbits) { /* Mismatch, nothing more to be found. */
/* Bit at offset 'plen' differed. */
*checkbits = plen + 1; /* Includes the first mismatching bit. */
return match_len;
}
/* Full match, check if rules exist at this prefix length. */
if (node->n_rules > 0) {
match_len = plen;
}
}
/* Dead end, exclude the other branch if it exists. */
*checkbits = !prev || trie_is_leaf(prev) ? plen : plen + 1;
return match_len;
}
static unsigned int
trie_lookup(const struct cls_trie *trie, const struct flow *flow,
unsigned int *checkbits)
{
const struct mf_field *mf = trie->field;
/* Check that current flow matches the prerequisites for the trie
* field. Some match fields are used for multiple purposes, so we
* must check that the trie is relevant for this flow. */
if (mf_are_prereqs_ok(mf, flow)) {
return trie_lookup_value(trie->root,
&((ovs_be32 *)flow)[mf->flow_be32ofs],
checkbits);
}
*checkbits = 0; /* Value not used in this case. */
return UINT_MAX;
}
/* Returns the length of a prefix match mask for the field 'mf' in 'minimask'.
* Returns the u32 offset to the miniflow data in '*miniflow_index', if
* 'miniflow_index' is not NULL. */
static unsigned int
minimask_get_prefix_len(const struct minimask *minimask,
const struct mf_field *mf)
{
unsigned int nbits = 0, mask_tz = 0; /* Non-zero when end of mask seen. */
uint8_t u32_ofs = mf->flow_be32ofs;
uint8_t u32_end = u32_ofs + mf->n_bytes / 4;
for (; u32_ofs < u32_end; ++u32_ofs) {
uint32_t mask;
mask = ntohl((OVS_FORCE ovs_be32)minimask_get(minimask, u32_ofs));
/* Validate mask, count the mask length. */
if (mask_tz) {
if (mask) {
return 0; /* No bits allowed after mask ended. */
}
} else {
if (~mask & (~mask + 1)) {
return 0; /* Mask not contiguous. */
}
mask_tz = ctz32(mask);
nbits += 32 - mask_tz;
}
}
return nbits;
}
/*
* This is called only when mask prefix is known to be CIDR and non-zero.
* Relies on the fact that the flow and mask have the same map, and since
* the mask is CIDR, the storage for the flow field exists even if it
* happened to be zeros.
*/
static const ovs_be32 *
minimatch_get_prefix(const struct minimatch *match, const struct mf_field *mf)
{
return match->flow.values +
count_1bits(match->flow.map & ((UINT64_C(1) << mf->flow_be32ofs) - 1));
}
/* Insert rule in to the prefix tree.
* 'mlen' must be the (non-zero) CIDR prefix length of the 'trie->field' mask
* in 'rule'. */
static void
trie_insert(struct cls_trie *trie, const struct cls_rule *rule, int mlen)
{
const ovs_be32 *prefix = minimatch_get_prefix(&rule->match, trie->field);
struct trie_node *node;
struct trie_node **edge;
int ofs = 0;
/* Walk the tree. */
for (edge = &trie->root;
(node = *edge) != NULL;
edge = trie_next_edge(node, prefix, ofs)) {
unsigned int eqbits = trie_prefix_equal_bits(node, prefix, ofs, mlen);
ofs += eqbits;
if (eqbits < node->nbits) {
/* Mismatch, new node needs to be inserted above. */
int old_branch = get_bit_at(node->prefix, eqbits);
/* New parent node. */
*edge = trie_branch_create(prefix, ofs - eqbits, eqbits,
ofs == mlen ? 1 : 0);
/* Adjust old node for its new position in the tree. */
node->prefix <<= eqbits;
node->nbits -= eqbits;
(*edge)->edges[old_branch] = node;
/* Check if need a new branch for the new rule. */
if (ofs < mlen) {
(*edge)->edges[!old_branch]
= trie_branch_create(prefix, ofs, mlen - ofs, 1);
}
return;
}
/* Full match so far. */
if (ofs == mlen) {
/* Full match at the current node, rule needs to be added here. */
node->n_rules++;
return;
}
}
/* Must insert a new tree branch for the new rule. */
*edge = trie_branch_create(prefix, ofs, mlen - ofs, 1);
}
/* 'mlen' must be the (non-zero) CIDR prefix length of the 'trie->field' mask
* in 'rule'. */
static void
trie_remove(struct cls_trie *trie, const struct cls_rule *rule, int mlen)
{
const ovs_be32 *prefix = minimatch_get_prefix(&rule->match, trie->field);
struct trie_node *node;
struct trie_node **edges[sizeof(union mf_value) * 8];
int depth = 0, ofs = 0;
/* Walk the tree. */
for (edges[depth] = &trie->root;
(node = *edges[depth]) != NULL;
edges[++depth] = trie_next_edge(node, prefix, ofs)) {
unsigned int eqbits = trie_prefix_equal_bits(node, prefix, ofs, mlen);
if (eqbits < node->nbits) {
/* Mismatch, nothing to be removed. This should never happen, as
* only rules in the classifier are ever removed. */
break; /* Log a warning. */
}
/* Full match so far. */
ofs += eqbits;
if (ofs == mlen) {
/* Full prefix match at the current node, remove rule here. */
if (!node->n_rules) {
break; /* Log a warning. */
}
node->n_rules--;
/* Check if can prune the tree. */
while (!node->n_rules && !(node->edges[0] && node->edges[1])) {
/* No rules and at most one child node, remove this node. */
struct trie_node *next;
next = node->edges[0] ? node->edges[0] : node->edges[1];
if (next) {
if (node->nbits + next->nbits > TRIE_PREFIX_BITS) {
break; /* Cannot combine. */
}
/* Combine node with next. */
next->prefix = node->prefix | next->prefix >> node->nbits;
next->nbits += node->nbits;
}
trie_node_destroy(node);
/* Update the parent's edge. */
*edges[depth] = next;
if (next || !depth) {
/* Branch not pruned or at root, nothing more to do. */
break;
}
node = *edges[--depth];
}
return;
}
}
/* Cannot go deeper. This should never happen, since only rules
* that actually exist in the classifier are ever removed. */
VLOG_WARN("Trying to remove non-existing rule from a prefix trie.");
}
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