X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=lib%2Fclassifier.h;h=0e39012b83b83ba66e624eb6ec89358c985434de;hb=0141e875a14cc30fe9c207a83616861055531d4d;hp=a14a24d2765d244b89cb5b8bf33d7af0aea25f10;hpb=cc36576070df622d0fc7a6e26ce01027e12b5b59;p=sliver-openvswitch.git

diff --git a/lib/classifier.h b/lib/classifier.h
index a14a24d27..0e39012b8 100644
--- a/lib/classifier.h
+++ b/lib/classifier.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2009, 2010, 2011, 2012 Nicira, Inc.
+ * 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.
@@ -19,29 +19,113 @@
 
 /* Flow classifier.
  *
- * A classifier is a "struct classifier",
- *      a hash map from a set of wildcards to a "struct cls_table",
- *              a hash map from fixed field values to "struct cls_rule",
- *                      which can contain a list of otherwise identical rules
- *                      with lower priorities.
- */
+ *
+ * What?
+ * =====
+ *
+ * A flow classifier holds any number of "rules", each of which specifies
+ * values to match for some fields or subfields and a priority.  The primary
+ * design goal for the classifier is that, given a packet, it can as quickly as
+ * possible find the highest-priority rule that matches the packet.
+ *
+ * Each OpenFlow table is implemented as a flow classifier.
+ *
+ *
+ * Basic Design
+ * ============
+ *
+ * Suppose that all the rules in a classifier had the same form.  For example,
+ * suppose that they all matched on the source and destination Ethernet address
+ * and wildcarded all the other fields.  Then the obvious way to implement a
+ * classifier would be a hash table on the source and destination Ethernet
+ * addresses.  If new classification rules came along with a different form,
+ * you could add a second hash table that hashed on the fields matched in those
+ * rules.  With two hash tables, you look up a given flow in each hash table.
+ * If there are no matches, the classifier didn't contain a match; if you find
+ * a match in one of them, that's the result; if you find a match in both of
+ * them, then the result is the rule with the higher priority.
+ *
+ * This is how the classifier works.  In a "struct classifier", each form of
+ * "struct cls_rule" present (based on its ->match.mask) goes into a separate
+ * "struct cls_table".  A lookup does a hash lookup in every "struct cls_table"
+ * in the classifier and tracks the highest-priority match that it finds.  The
+ * tables are kept in a descending priority order according to the highest
+ * priority rule in each table, which allows lookup to skip over tables that
+ * can't possibly have a higher-priority match than already found.
+ *
+ * One detail: a classifier can contain multiple rules that are identical other
+ * than their priority.  When this happens, only the highest priority rule out
+ * of a group of otherwise identical rules is stored directly in the "struct
+ * cls_table", with the other almost-identical rules chained off a linked list
+ * inside that highest-priority rule.
+ *
+ *
+ * Partitioning
+ * ============
+ *
+ * Suppose that a given classifier is being used to handle multiple stages in a
+ * pipeline using "resubmit", with metadata (that is, the OpenFlow 1.1+ field
+ * named "metadata") distinguishing between the different stages.  For example,
+ * metadata value 1 might identify ingress rules, metadata value 2 might
+ * identify ACLs, and metadata value 3 might identify egress rules.  Such a
+ * classifier is essentially partitioned into multiple sub-classifiers on the
+ * basis of the metadata value.
+ *
+ * The classifier has a special optimization to speed up matching in this
+ * scenario:
+ *
+ *     - Each cls_table that matches on metadata gets a tag derived from the
+ *       table's mask, so that it is likely that each table has a unique tag.
+ *       (Duplicate tags have a performance cost but do not affect
+ *       correctness.)
+ *
+ *     - For each metadata value matched by any cls_rule, the classifier
+ *       constructs a "struct cls_partition" indexed by the metadata value.
+ *       The cls_partition has a 'tags' member whose value is the bitwise-OR of
+ *       the tags of each cls_table that contains any rule that matches on the
+ *       cls_partition's metadata value.  In other words, struct cls_partition
+ *       associates metadata values with tables that need to be checked with
+ *       flows with that specific metadata value.
+ *
+ * Thus, a flow lookup can start by looking up the partition associated with
+ * the flow's metadata, and then skip over any cls_table whose 'tag' does not
+ * intersect the partition's 'tags'.  (The flow must also be looked up in any
+ * cls_table that doesn't match on metadata.  We handle that by giving any such
+ * cls_table TAG_ALL as its 'tags' so that it matches any tag.)
+ *
+ *
+ * Thread-safety
+ * =============
+ *
+ * When locked properly, the classifier is thread safe as long as the following
+ * conditions are satisfied.
+ * - Only the main thread calls functions requiring a write lock.
+ * - Only the main thread is allowed to iterate over rules. */
 
 #include "flow.h"
 #include "hmap.h"
 #include "list.h"
 #include "match.h"
+#include "tag.h"
 #include "openflow/nicira-ext.h"
 #include "openflow/openflow.h"
+#include "ovs-thread.h"
+#include "util.h"
 
 #ifdef __cplusplus
 extern "C" {
 #endif
 
+/* Needed only for the lock annotation in struct classifier. */
+extern struct ovs_mutex ofproto_mutex;
+
 /* A flow classifier. */
 struct classifier {
     int n_rules;                /* Total number of rules. */
     struct hmap tables;         /* Contains "struct cls_table"s.  */
     struct list tables_priority; /* Tables in descending priority order */
+    struct hmap partitions;     /* Contains "struct cls_partition"s. */
+    struct ovs_rwlock rwlock OVS_ACQ_AFTER(ofproto_mutex);
 };
 
 /* A set of rules that all have the same fields wildcarded. */
@@ -53,6 +137,7 @@ struct cls_table {
     int n_table_rules;          /* Number of rules, including duplicates. */
     unsigned int max_priority;  /* Max priority of any rule in the table. */
     unsigned int max_count;     /* Count of max_priority rules. */
+    tag_type tag;               /* Tag generated from mask for partitioning. */
 };
 
 /* Returns true if 'table' is a "catch-all" table that will match every
@@ -69,6 +154,17 @@ struct cls_rule {
     struct list list;           /* List of identical, lower-priority rules. */
     struct minimatch match;     /* Matching rule. */
     unsigned int priority;      /* Larger numbers are higher priorities. */
+    struct cls_partition *partition;
+};
+
+/* Associates a metadata value (that is, a value of the OpenFlow 1.1+ metadata
+ * field) with tags for the "cls_table"s that contain rules that match that
+ * metadata value.  */
+struct cls_partition {
+    struct hmap_node hmap_node; /* In struct classifier's 'partitions' hmap. */
+    ovs_be64 metadata;          /* metadata value for this partition. */
+    tag_type tags;              /* OR of each included flow's cls_table tag. */
+    struct tag_tracker tracker; /* Tracks the bits in 'tags'. */
 };
 
 void cls_rule_init(struct cls_rule *, const struct match *,
@@ -76,6 +172,7 @@ void cls_rule_init(struct cls_rule *, const struct match *,
 void cls_rule_init_from_minimatch(struct cls_rule *, const struct minimatch *,
                                   unsigned int priority);
 void cls_rule_clone(struct cls_rule *, const struct cls_rule *);
+void cls_rule_move(struct cls_rule *dst, struct cls_rule *src);
 void cls_rule_destroy(struct cls_rule *);
 
 bool cls_rule_equal(const struct cls_rule *, const struct cls_rule *);
@@ -88,26 +185,35 @@ bool cls_rule_is_catchall(const struct cls_rule *);
 bool cls_rule_is_loose_match(const struct cls_rule *rule,
                              const struct minimatch *criteria);
 
-void classifier_init(struct classifier *);
+void classifier_init(struct classifier *cls);
 void classifier_destroy(struct classifier *);
-bool classifier_is_empty(const struct classifier *);
-int classifier_count(const struct classifier *);
-void classifier_insert(struct classifier *, struct cls_rule *);
-struct cls_rule *classifier_replace(struct classifier *, struct cls_rule *);
-void classifier_remove(struct classifier *, struct cls_rule *);
-struct cls_rule *classifier_lookup(const struct classifier *,
+bool classifier_is_empty(const struct classifier *cls)
+    OVS_REQ_RDLOCK(cls->rwlock);
+int classifier_count(const struct classifier *cls)
+    OVS_REQ_RDLOCK(cls->rwlock);
+void classifier_insert(struct classifier *cls, struct cls_rule *)
+    OVS_REQ_WRLOCK(cls->rwlock);
+struct cls_rule *classifier_replace(struct classifier *cls, struct cls_rule *)
+    OVS_REQ_WRLOCK(cls->rwlock);
+void classifier_remove(struct classifier *cls, struct cls_rule *)
+    OVS_REQ_WRLOCK(cls->rwlock);
+struct cls_rule *classifier_lookup(const struct classifier *cls,
                                    const struct flow *,
-                                   struct flow_wildcards *);
-bool classifier_rule_overlaps(const struct classifier *,
-                              const struct cls_rule *);
+                                   struct flow_wildcards *)
+    OVS_REQ_RDLOCK(cls->rwlock);
+bool classifier_rule_overlaps(const struct classifier *cls,
+                              const struct cls_rule *)
+    OVS_REQ_RDLOCK(cls->rwlock);
 
 typedef void cls_cb_func(struct cls_rule *, void *aux);
 
-struct cls_rule *classifier_find_rule_exactly(const struct classifier *,
-                                              const struct cls_rule *);
-struct cls_rule *classifier_find_match_exactly(const struct classifier *,
+struct cls_rule *classifier_find_rule_exactly(const struct classifier *cls,
+                                              const struct cls_rule *)
+    OVS_REQ_RDLOCK(cls->rwlock);
+struct cls_rule *classifier_find_match_exactly(const struct classifier *cls,
                                                const struct match *,
-                                               unsigned int priority);
+                                               unsigned int priority)
+    OVS_REQ_RDLOCK(cls->rwlock);
 
 /* Iteration. */
 
@@ -117,10 +223,10 @@ struct cls_cursor {
     const struct cls_rule *target;
 };
 
-void cls_cursor_init(struct cls_cursor *, const struct classifier *,
-                     const struct cls_rule *match);
-struct cls_rule *cls_cursor_first(struct cls_cursor *);
-struct cls_rule *cls_cursor_next(struct cls_cursor *, struct cls_rule *);
+void cls_cursor_init(struct cls_cursor *cursor, const struct classifier *cls,
+                     const struct cls_rule *match) OVS_REQ_RDLOCK(cls->rwlock);
+struct cls_rule *cls_cursor_first(struct cls_cursor *cursor);
+struct cls_rule *cls_cursor_next(struct cls_cursor *cursor, const struct cls_rule *);
 
 #define CLS_CURSOR_FOR_EACH(RULE, MEMBER, CURSOR)                       \
     for (ASSIGN_CONTAINER(RULE, cls_cursor_first(CURSOR), MEMBER);      \