classifier already provides lockless lookups, and protected
modifications. When user wants to remove a flow, we currently require
the flow to exist in the classifier. To be thread safe, this requires
the caller to introduce their own mutex, lock it before a lookup, and
then issue classifier_remove() while the lock is still held.
This patch relaxes the "existence requirement" of the rule in
classifier_remove(), allowing it to be called on a rule that may have
already been removed from the classifier. This allows users to do a
classifier_lookup() and classifier_remove() without additional
syncronization.
Signed-off-by: Jarno Rajahalme <jrajaha...@nicira.com>
---
lib/classifier.c | 24 ++++++++++++++++++------
lib/classifier.h | 2 +-
2 files changed, 19 insertions(+), 7 deletions(-)
diff --git a/lib/classifier.c b/lib/classifier.c
index a5ffe85..f30ba95 100644
--- a/lib/classifier.c
+++ b/lib/classifier.c
@@ -770,22 +770,31 @@ classifier_insert(struct classifier *cls, struct cls_rule
*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
+ * resides, etc., as necessary.
+ *
+ * Does nothing if 'rule' has been already removed, or was never inserted.
+ *
+ * Returns the removed rule, or NULL, if it was already removed.
+ */
+struct cls_rule *
classifier_remove(struct classifier *cls, struct cls_rule *rule)
OVS_EXCLUDED(cls->mutex)
{
struct cls_partition *partition;
- struct cls_match *cls_match = rule->cls_match;
+ struct cls_match *cls_match;
struct cls_match *head;
struct cls_subtable *subtable;
int i;
uint32_t basis = 0, hash, ihash[CLS_MAX_INDICES];
uint8_t prev_be32ofs = 0;
- ovs_assert(cls_match);
-
ovs_mutex_lock(&cls->mutex);
+ cls_match = rule->cls_match;
+ if (!cls_match) {
+ rule = NULL;
+ goto unlock; /* Already removed. */
+ }
+
subtable = find_subtable(cls, &rule->match.mask);
ovs_assert(subtable);
@@ -858,9 +867,12 @@ classifier_remove(struct classifier *cls, struct cls_rule
*rule)
cls->n_rules--;
- rule->cls_match = NULL;
ovsrcu_postpone(free, cls_match);
+ rule->cls_match = NULL;
+unlock:
ovs_mutex_unlock(&cls->mutex);
+
+ return rule;
}
/* Prefix tree context. Valid when 'lookup_done' is true. Can skip all
diff --git a/lib/classifier.h b/lib/classifier.h
index f75d242..d1f4e86 100644
--- a/lib/classifier.h
+++ b/lib/classifier.h
@@ -291,7 +291,7 @@ 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_remove(struct classifier *, struct cls_rule *);
struct cls_rule *classifier_lookup(const struct classifier *,
const struct flow *,
struct flow_wildcards *);
--
1.7.10.4
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