2 * Copyright (c) 2009 Nicira Networks.
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at:
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
18 #include "classifier.h"
21 #include <netinet/in.h>
25 const struct cls_field cls_fields[CLS_N_FIELDS + 1] = {
26 #define CLS_FIELD(WILDCARDS, MEMBER, NAME) \
27 { offsetof(flow_t, MEMBER), \
28 sizeof ((flow_t *)0)->MEMBER, \
33 { sizeof(flow_t), 0, 0, "exact" },
36 static uint32_t hash_fields(const flow_t *, int table_idx);
37 static bool equal_fields(const flow_t *, const flow_t *, int table_idx);
39 static int table_idx_from_wildcards(uint32_t wildcards);
40 static struct cls_rule *table_insert(struct hmap *, struct cls_rule *);
41 static struct cls_rule *insert_exact_rule(struct classifier *,
43 static struct cls_bucket *find_bucket(struct hmap *, size_t hash,
44 const struct cls_rule *);
45 static struct cls_rule *search_table(const struct hmap *table, int field_idx,
46 const struct cls_rule *);
47 static struct cls_rule *search_exact_table(const struct classifier *,
48 size_t hash, const flow_t *);
49 static bool rules_match_1wild(const struct cls_rule *fixed,
50 const struct cls_rule *wild, int field_idx);
52 /* Converts the flow in 'flow' into a cls_rule in 'rule', with the given
53 * 'wildcards' and 'priority'.*/
55 cls_rule_from_flow(struct cls_rule *rule, const flow_t *flow,
56 uint32_t wildcards, unsigned int priority)
58 assert(flow->reserved == 0);
60 flow_wildcards_init(&rule->wc, wildcards);
61 rule->priority = priority;
62 rule->table_idx = table_idx_from_wildcards(rule->wc.wildcards);
65 /* Converts the ofp_match in 'match' into a cls_rule in 'rule', with the given
68 cls_rule_from_match(struct cls_rule *rule, const struct ofp_match *match,
69 unsigned int priority)
72 flow_from_match(&rule->flow, &wildcards, match);
73 flow_wildcards_init(&rule->wc, wildcards);
74 rule->priority = rule->wc.wildcards ? priority : UINT16_MAX;
75 rule->table_idx = table_idx_from_wildcards(rule->wc.wildcards);
78 /* Prints cls_rule 'rule', for debugging.
80 * (The output could be improved and expanded, but this was good enough to
81 * debug the classifier.) */
83 cls_rule_print(const struct cls_rule *rule)
85 printf("wildcards=%x priority=%u ", rule->wc.wildcards, rule->priority);
86 flow_print(stdout, &rule->flow);
90 /* Adjusts pointers around 'old', which must be in classifier 'cls', to
91 * compensate for it having been moved in memory to 'new' (e.g. due to
94 * This function cannot be realized in all possible flow classifier
95 * implementations, so we will probably have to change the interface if we
96 * change the implementation. Shouldn't be a big deal though. */
98 cls_rule_moved(struct classifier *cls, struct cls_rule *old,
102 if (new->wc.wildcards) {
103 list_moved(&new->node.list);
105 hmap_moved(&cls->exact_table, &old->node.hmap, &new->node.hmap);
110 /* Replaces 'old', which must be in classifier 'cls', by 'new' (e.g. due to
111 * realloc()); that is, after calling this function 'new' will be in 'cls' in
114 * 'new' and 'old' must be exactly the same: wildcard the same fields, have the
115 * same fixed values for non-wildcarded fields, and have the same priority.
117 * The caller takes ownership of 'old' and is thus responsible for freeing it,
118 * etc., as necessary.
120 * This function cannot be realized in all possible flow classifier
121 * implementations, so we will probably have to change the interface if we
122 * change the implementation. Shouldn't be a big deal though. */
124 cls_rule_replace(struct classifier *cls, const struct cls_rule *old,
125 struct cls_rule *new)
128 assert(old->wc.wildcards == new->wc.wildcards);
129 assert(old->priority == new->priority);
131 if (new->wc.wildcards) {
132 list_replace(&new->node.list, &old->node.list);
134 hmap_replace(&cls->exact_table, &old->node.hmap, &new->node.hmap);
138 /* Initializes 'cls' as a classifier that initially contains no classification
141 classifier_init(struct classifier *cls)
146 for (i = 0; i < ARRAY_SIZE(cls->tables); i++) {
147 hmap_init(&cls->tables[i]);
149 hmap_init(&cls->exact_table);
152 /* Destroys 'cls'. Rules within 'cls', if any, are not freed; this is the
153 * caller's responsibility. */
155 classifier_destroy(struct classifier *cls)
158 struct cls_bucket *bucket, *next_bucket;
161 for (tbl = &cls->tables[0]; tbl < &cls->tables[CLS_N_FIELDS]; tbl++) {
162 HMAP_FOR_EACH_SAFE (bucket, next_bucket,
163 struct cls_bucket, hmap_node, tbl) {
168 hmap_destroy(&cls->exact_table);
172 /* Returns true if 'cls' does not contain any classification rules, false
175 classifier_is_empty(const struct classifier *cls)
177 return cls->n_rules == 0;
180 /* Returns the number of rules in 'classifier'. */
182 classifier_count(const struct classifier *cls)
187 /* Returns the number of rules in 'classifier' that have no wildcards. */
189 classifier_count_exact(const struct classifier *cls)
191 return hmap_count(&cls->exact_table);
194 /* Inserts 'rule' into 'cls'. Transfers ownership of 'rule' to 'cls'.
196 * If 'cls' already contains an identical rule (including wildcards, values of
197 * fixed fields, and priority), replaces the old rule by 'rule' and returns the
198 * rule that was replaced. The caller takes ownership of the returned rule and
199 * is thus responsible for freeing it, etc., as necessary.
201 * Returns NULL if 'cls' does not contain a rule with an identical key, after
202 * inserting the new rule. In this case, no rules are displaced by the new
203 * rule, even rules that cannot have any effect because the new rule matches a
204 * superset of their flows and has higher priority. */
206 classifier_insert(struct classifier *cls, struct cls_rule *rule)
208 struct cls_rule *old;
209 assert((rule->wc.wildcards == 0) == (rule->table_idx == CLS_F_IDX_EXACT));
210 old = (rule->wc.wildcards
211 ? table_insert(&cls->tables[rule->table_idx], rule)
212 : insert_exact_rule(cls, rule));
219 /* Inserts 'rule' into 'cls'. Transfers ownership of 'rule' to 'cls'.
221 * 'rule' must be an exact-match rule (rule->wc.wildcards must be 0) and 'cls'
222 * must not contain any rule with an identical key. */
224 classifier_insert_exact(struct classifier *cls, struct cls_rule *rule)
226 hmap_insert(&cls->exact_table, &rule->node.hmap,
227 flow_hash(&rule->flow, 0));
231 /* Removes 'rule' from 'cls'. It is caller's responsibility to free 'rule', if
232 * this is desirable. */
234 classifier_remove(struct classifier *cls, struct cls_rule *rule)
236 if (rule->wc.wildcards) {
237 /* Remove 'rule' from bucket. If that empties the bucket, remove the
238 * bucket from its table. */
239 struct hmap *table = &cls->tables[rule->table_idx];
240 struct list *rules = list_remove(&rule->node.list);
241 if (list_is_empty(rules)) {
242 /* This code is a little tricky. list_remove() returns the list
243 * element just after the one removed. Since the list is now
244 * empty, this will be the address of the 'rules' member of the
245 * bucket that was just emptied, so pointer arithmetic (via
246 * CONTAINER_OF) can find that bucket. */
247 struct cls_bucket *bucket;
248 bucket = CONTAINER_OF(rules, struct cls_bucket, rules);
249 hmap_remove(table, &bucket->hmap_node);
253 /* Remove 'rule' from cls->exact_table. */
254 hmap_remove(&cls->exact_table, &rule->node.hmap);
259 /* Finds and returns the highest-priority rule in 'cls' that matches 'flow'.
260 * Returns a null pointer if no rules in 'cls' match 'flow'. If multiple rules
261 * of equal priority match 'flow', returns one arbitrarily.
263 * (When multiple rules of equal priority happen to fall into the same bucket,
264 * rules added more recently take priority over rules added less recently, but
265 * this is subject to change and should not be depended upon.) */
267 classifier_lookup(const struct classifier *cls, const flow_t *flow)
269 struct cls_rule *rule = classifier_lookup_exact(cls, flow);
271 rule = classifier_lookup_wild(cls, flow);
277 classifier_lookup_exact(const struct classifier *cls, const flow_t *flow)
279 return (!hmap_is_empty(&cls->exact_table)
280 ? search_exact_table(cls, flow_hash(flow, 0), flow)
285 classifier_lookup_wild(const struct classifier *cls, const flow_t *flow)
287 struct cls_rule *best = NULL;
288 if (cls->n_rules > hmap_count(&cls->exact_table)) {
289 struct cls_rule target;
292 cls_rule_from_flow(&target, flow, 0, 0);
293 for (i = 0; i < CLS_N_FIELDS; i++) {
294 struct cls_rule *rule = search_table(&cls->tables[i], i, &target);
295 if (rule && (!best || rule->priority > best->priority)) {
304 classifier_find_rule_exactly(const struct classifier *cls,
305 const flow_t *target, uint32_t wildcards,
306 unsigned int priority)
308 struct cls_bucket *bucket;
313 /* Ignores 'priority'. */
314 return search_exact_table(cls, flow_hash(target, 0), target);
317 assert(wildcards == (wildcards & OFPFW_ALL));
318 table_idx = table_idx_from_wildcards(wildcards);
319 hash = hash_fields(target, table_idx);
320 HMAP_FOR_EACH_WITH_HASH (bucket, struct cls_bucket, hmap_node, hash,
321 &cls->tables[table_idx]) {
322 if (equal_fields(&bucket->fixed, target, table_idx)) {
323 struct cls_rule *pos;
324 LIST_FOR_EACH (pos, struct cls_rule, node.list, &bucket->rules) {
325 if (pos->priority < priority) {
327 } else if (pos->priority == priority &&
328 pos->wc.wildcards == wildcards &&
329 flow_equal(target, &pos->flow)) {
338 /* Ignores target->priority.
340 * 'callback' is allowed to delete the rule that is passed as its argument, but
341 * it must not delete (or move) any other rules in 'cls' that are in the same
342 * table as the argument rule. Two rules are in the same table if their
343 * cls_rule structs have the same table_idx; as a special case, a rule with
344 * wildcards and an exact-match rule will never be in the same table. */
346 classifier_for_each_match(const struct classifier *cls,
347 const struct cls_rule *target,
348 int include, cls_cb_func *callback, void *aux)
350 if (include & CLS_INC_WILD) {
351 const struct hmap *table;
353 for (table = &cls->tables[0]; table < &cls->tables[CLS_N_FIELDS];
355 struct cls_bucket *bucket, *next_bucket;
357 HMAP_FOR_EACH_SAFE (bucket, next_bucket,
358 struct cls_bucket, hmap_node, table) {
359 /* XXX there is a bit of room for optimization here based on
360 * rejecting entire buckets on their fixed fields, but it will
361 * only be worthwhile for big buckets (which we hope we won't
362 * get anyway, but...) */
363 struct cls_rule *prev_rule, *rule;
365 /* We can't just use LIST_FOR_EACH_SAFE here because, if the
366 * callback deletes the last rule in the bucket, then the
367 * bucket itself will be destroyed. The bucket contains the
368 * list head so that's a use-after-free error. */
370 LIST_FOR_EACH (rule, struct cls_rule, node.list,
372 if (rules_match_1wild(rule, target, 0)) {
374 callback(prev_rule, aux);
380 callback(prev_rule, aux);
386 if (include & CLS_INC_EXACT) {
387 if (target->wc.wildcards) {
388 struct cls_rule *rule, *next_rule;
390 HMAP_FOR_EACH_SAFE (rule, next_rule, struct cls_rule, node.hmap,
392 if (rules_match_1wild(rule, target, 0)) {
397 /* Optimization: there can be at most one match in the exact
399 size_t hash = flow_hash(&target->flow, 0);
400 struct cls_rule *rule = search_exact_table(cls, hash,
409 /* 'callback' is allowed to delete the rule that is passed as its argument, but
410 * it must not delete (or move) any other rules in 'cls' that are in the same
411 * table as the argument rule. Two rules are in the same table if their
412 * cls_rule structs have the same table_idx; as a special case, a rule with
413 * wildcards and an exact-match rule will never be in the same table. */
415 classifier_for_each(const struct classifier *cls, int include,
416 void (*callback)(struct cls_rule *, void *aux),
419 if (include & CLS_INC_WILD) {
420 const struct hmap *tbl;
422 for (tbl = &cls->tables[0]; tbl < &cls->tables[CLS_N_FIELDS]; tbl++) {
423 struct cls_bucket *bucket, *next_bucket;
425 HMAP_FOR_EACH_SAFE (bucket, next_bucket,
426 struct cls_bucket, hmap_node, tbl) {
427 struct cls_rule *prev_rule, *rule;
429 /* We can't just use LIST_FOR_EACH_SAFE here because, if the
430 * callback deletes the last rule in the bucket, then the
431 * bucket itself will be destroyed. The bucket contains the
432 * list head so that's a use-after-free error. */
434 LIST_FOR_EACH (rule, struct cls_rule, node.list,
437 callback(prev_rule, aux);
442 callback(prev_rule, aux);
448 if (include & CLS_INC_EXACT) {
449 struct cls_rule *rule, *next_rule;
451 HMAP_FOR_EACH_SAFE (rule, next_rule,
452 struct cls_rule, node.hmap, &cls->exact_table) {
458 static struct cls_bucket *create_bucket(struct hmap *, size_t hash,
459 const flow_t *fixed);
460 static struct cls_rule *bucket_insert(struct cls_bucket *, struct cls_rule *);
462 static inline bool equal_bytes(const void *, const void *, size_t n);
464 /* Returns a hash computed across the fields in 'flow' whose field indexes
465 * (CLS_F_IDX_*) are less than 'table_idx'. (If 'table_idx' is
466 * CLS_F_IDX_EXACT, hashes all the fields in 'flow'). */
468 hash_fields(const flow_t *flow, int table_idx)
470 /* I just know I'm going to hell for writing code this way.
472 * GCC generates pretty good code here, with only a single taken
473 * conditional jump per execution. Now the question is, would we be better
474 * off marking this function ALWAYS_INLINE and writing a wrapper that
475 * switches on the value of 'table_idx' to get rid of all the conditional
476 * jumps entirely (except for one in the wrapper)? Honestly I really,
477 * really hope that it doesn't matter in practice.
479 * We could do better by calculating hashes incrementally, instead of
480 * starting over from the top each time. But that would be even uglier. */
485 a = b = c = 0xdeadbeef + table_idx;
488 #define CLS_FIELD(WILDCARDS, MEMBER, NAME) \
489 if (table_idx == CLS_F_IDX_##NAME) { \
491 memset((uint8_t *) tmp + n, 0, sizeof tmp - n); \
494 const size_t size = sizeof flow->MEMBER; \
495 const uint8_t *p1 = (const uint8_t *) &flow->MEMBER; \
496 const size_t p1_size = MIN(sizeof tmp - n, size); \
497 const uint8_t *p2 = p1 + p1_size; \
498 const size_t p2_size = size - p1_size; \
500 /* Append to 'tmp' as much data as will fit. */ \
501 memcpy((uint8_t *) tmp + n, p1, p1_size); \
504 /* If 'tmp' is full, mix. */ \
505 if (n == sizeof tmp) { \
513 /* Append to 'tmp' any data that didn't fit. */ \
514 memcpy(tmp, p2, p2_size); \
528 /* Compares the fields in 'a' and 'b' whose field indexes (CLS_F_IDX_*) are
529 * less than 'table_idx'. (If 'table_idx' is CLS_F_IDX_EXACT, compares all the
530 * fields in 'a' and 'b').
532 * Returns true if all the compared fields are equal, false otherwise. */
534 equal_fields(const flow_t *a, const flow_t *b, int table_idx)
536 /* XXX The generated code could be better here. */
537 #define CLS_FIELD(WILDCARDS, MEMBER, NAME) \
538 if (table_idx == CLS_F_IDX_##NAME) { \
540 } else if (!equal_bytes(&a->MEMBER, &b->MEMBER, sizeof a->MEMBER)) { \
550 table_idx_from_wildcards(uint32_t wildcards)
553 return CLS_F_IDX_EXACT;
555 #define CLS_FIELD(WILDCARDS, MEMBER, NAME) \
556 if (wildcards & WILDCARDS) { \
557 return CLS_F_IDX_##NAME; \
564 /* Inserts 'rule' into 'table'. Returns the rule, if any, that was displaced
565 * in favor of 'rule'. */
566 static struct cls_rule *
567 table_insert(struct hmap *table, struct cls_rule *rule)
569 struct cls_bucket *bucket;
572 hash = hash_fields(&rule->flow, rule->table_idx);
573 bucket = find_bucket(table, hash, rule);
575 bucket = create_bucket(table, hash, &rule->flow);
578 return bucket_insert(bucket, rule);
581 /* Inserts 'rule' into 'bucket', given that 'field' is the first wildcarded
584 * Returns the rule, if any, that was displaced in favor of 'rule'. */
585 static struct cls_rule *
586 bucket_insert(struct cls_bucket *bucket, struct cls_rule *rule)
588 struct cls_rule *pos;
589 LIST_FOR_EACH (pos, struct cls_rule, node.list, &bucket->rules) {
590 if (pos->priority <= rule->priority) {
591 if (pos->priority == rule->priority
592 && pos->wc.wildcards == rule->wc.wildcards
593 && rules_match_1wild(pos, rule, rule->table_idx))
595 list_replace(&rule->node.list, &pos->node.list);
601 list_insert(&pos->node.list, &rule->node.list);
605 static struct cls_rule *
606 insert_exact_rule(struct classifier *cls, struct cls_rule *rule)
608 struct cls_rule *old_rule;
611 hash = flow_hash(&rule->flow, 0);
612 old_rule = search_exact_table(cls, hash, &rule->flow);
614 hmap_remove(&cls->exact_table, &old_rule->node.hmap);
616 hmap_insert(&cls->exact_table, &rule->node.hmap, hash);
620 /* Returns the bucket in 'table' that has the given 'hash' and the same fields
621 * as 'rule->flow' (up to 'rule->table_idx'), or a null pointer if no bucket
623 static struct cls_bucket *
624 find_bucket(struct hmap *table, size_t hash, const struct cls_rule *rule)
626 struct cls_bucket *bucket;
627 HMAP_FOR_EACH_WITH_HASH (bucket, struct cls_bucket, hmap_node, hash,
629 if (equal_fields(&bucket->fixed, &rule->flow, rule->table_idx)) {
636 /* Creates a bucket and inserts it in 'table' with the given 'hash' and 'fixed'
637 * values. Returns the new bucket. */
638 static struct cls_bucket *
639 create_bucket(struct hmap *table, size_t hash, const flow_t *fixed)
641 struct cls_bucket *bucket = xmalloc(sizeof *bucket);
642 list_init(&bucket->rules);
643 bucket->fixed = *fixed;
644 hmap_insert(table, &bucket->hmap_node, hash);
648 /* Returns true if the 'n' bytes in 'a' and 'b' are equal, false otherwise. */
649 static inline bool ALWAYS_INLINE
650 equal_bytes(const void *a, const void *b, size_t n)
653 /* For some reason GCC generates stupid code for memcmp() of small
654 * constant integer lengths. Help it out.
656 * This function is always inlined, and it is always called with 'n' as a
657 * compile-time constant, so the switch statement gets optimized out and
658 * this whole function just expands to an instruction or two. */
661 return *(uint8_t *) a == *(uint8_t *) b;
664 return *(uint16_t *) a == *(uint16_t *) b;
667 return *(uint32_t *) a == *(uint32_t *) b;
670 return (*(uint32_t *) a == *(uint32_t *) b
671 && ((uint16_t *) a)[2] == ((uint16_t *) b)[2]);
677 /* I hope GCC is smarter on your platform. */
678 return !memcmp(a, b, n);
682 /* Returns the 32-bit unsigned integer at 'p'. */
683 static inline uint32_t
684 read_uint32(const void *p)
686 /* GCC optimizes this into a single machine instruction on x86. */
688 memcpy(&x, p, sizeof x);
692 /* Compares the specified field in 'a' and 'b'. Returns true if the fields are
693 * equal, or if the ofp_match wildcard bits in 'wildcards' are set such that
694 * non-equal values may be ignored. 'nw_src_mask' and 'nw_dst_mask' must be
695 * those that would be set for 'wildcards' by cls_rule_set_masks().
697 * The compared field is the one with wildcard bit or bits 'field_wc', offset
698 * 'rule_ofs' within cls_rule's "fields" member, and length 'len', in bytes. */
699 static inline bool ALWAYS_INLINE
700 field_matches(const flow_t *a_, const flow_t *b_,
701 uint32_t wildcards, uint32_t nw_src_mask, uint32_t nw_dst_mask,
702 uint32_t field_wc, int ofs, int len)
704 /* This function is always inlined, and it is always called with 'field_wc'
705 * as a compile-time constant, so the "if" conditionals here generate no
707 const void *a = (const uint8_t *) a_ + ofs;
708 const void *b = (const uint8_t *) b_ + ofs;
709 if (!(field_wc & (field_wc - 1))) {
710 /* Handle all the single-bit wildcard cases. */
711 return wildcards & field_wc || equal_bytes(a, b, len);
712 } else if (field_wc == OFPFW_NW_SRC_MASK ||
713 field_wc == OFPFW_NW_DST_MASK) {
714 uint32_t a_ip = read_uint32(a);
715 uint32_t b_ip = read_uint32(b);
716 uint32_t mask = (field_wc == OFPFW_NW_SRC_MASK
717 ? nw_src_mask : nw_dst_mask);
718 return ((a_ip ^ b_ip) & mask) == 0;
724 /* Returns true if 'a' and 'b' match, ignoring fields for which the wildcards
725 * in 'wildcards' are set. 'nw_src_mask' and 'nw_dst_mask' must be those that
726 * would be set for 'wildcards' by cls_rule_set_masks(). 'field_idx' is the
727 * index of the first field to be compared; fields before 'field_idx' are
728 * assumed to match. (Always returns true if 'field_idx' is CLS_N_FIELDS.) */
730 rules_match(const struct cls_rule *a, const struct cls_rule *b,
731 uint32_t wildcards, uint32_t nw_src_mask, uint32_t nw_dst_mask,
734 /* This is related to Duff's device (see
735 * http://en.wikipedia.org/wiki/Duff's_device). */
737 #define CLS_FIELD(WILDCARDS, MEMBER, NAME) \
738 case CLS_F_IDX_##NAME: \
739 if (!field_matches(&a->flow, &b->flow, \
740 wildcards, nw_src_mask, nw_dst_mask, \
741 WILDCARDS, offsetof(flow_t, MEMBER), \
742 sizeof a->flow.MEMBER)) { \
752 /* Returns true if 'fixed' and 'wild' match. All fields in 'fixed' must have
753 * fixed values; 'wild' may contain wildcards.
755 * 'field_idx' is the index of the first field to be compared; fields before
756 * 'field_idx' are assumed to match. Always returns true if 'field_idx' is
759 rules_match_1wild(const struct cls_rule *fixed, const struct cls_rule *wild,
762 return rules_match(fixed, wild, wild->wc.wildcards, wild->wc.nw_src_mask,
763 wild->wc.nw_dst_mask, field_idx);
766 /* Searches 'bucket' for a rule that matches 'target'. Returns the
767 * highest-priority match, if one is found, or a null pointer if there is no
770 * 'field_idx' must be the index of the first wildcarded field in 'bucket'. */
771 static struct cls_rule *
772 search_bucket(struct cls_bucket *bucket, int field_idx,
773 const struct cls_rule *target)
775 struct cls_rule *pos;
777 if (!equal_fields(&bucket->fixed, &target->flow, field_idx)) {
781 LIST_FOR_EACH (pos, struct cls_rule, node.list, &bucket->rules) {
782 if (rules_match_1wild(target, pos, field_idx)) {
789 /* Searches 'table' for a rule that matches 'target'. Returns the
790 * highest-priority match, if one is found, or a null pointer if there is no
793 * 'field_idx' must be the index of the first wildcarded field in 'table'. */
794 static struct cls_rule *
795 search_table(const struct hmap *table, int field_idx,
796 const struct cls_rule *target)
798 struct cls_bucket *bucket;
800 switch (hmap_count(table)) {
801 /* In these special cases there's no need to hash. */
805 bucket = CONTAINER_OF(hmap_first(table), struct cls_bucket, hmap_node);
806 return search_bucket(bucket, field_idx, target);
809 HMAP_FOR_EACH_WITH_HASH (bucket, struct cls_bucket, hmap_node,
810 hash_fields(&target->flow, field_idx), table) {
811 struct cls_rule *rule = search_bucket(bucket, field_idx, target);
819 static struct cls_rule *
820 search_exact_table(const struct classifier *cls, size_t hash,
821 const flow_t *target)
823 struct cls_rule *rule;
825 HMAP_FOR_EACH_WITH_HASH (rule, struct cls_rule, node.hmap,
826 hash, &cls->exact_table) {
827 if (flow_equal(&rule->flow, target)) {