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classifier: Store n_indices between usage.

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Currently the Clang analyzer will complain about usage of an
uninitialized variable in the classifier. This is a false positive, but
not for a reason that could easily be detectable by clang.

The classifier is not safe for multiple writer threads to use
simultaneously so all callers protect these functions from simultaneous
writes. However, this is not so clear from the code's static analysis
alone. To help Clang out here, the n_indicies count is saved onto the
stack instead of accessed from the subtables struct repeatedly.

Acked-by: Simon Horman <horms@ovn.org>
Signed-off-by: Mike Pattrick <mkp@redhat.com>
Signed-off-by: Eelco Chaudron <echaudro@redhat.com>
This commit is contained in:
Mike Pattrick
2024-09-09 00:55:02 -04:00
committed by Eelco Chaudron
parent cfc8321da1
commit 3d6b048d84
1 changed files with 8 additions and 4 deletions
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12
lib/classifier.c
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@@ -527,6 +527,7 @@ classifier_replace(struct classifier *cls, const struct cls_rule *rule,
struct cls_match *head;
unsigned int mask_offset;
size_t n_rules = 0;
uint8_t n_indices;
uint32_t basis;
uint32_t hash;
unsigned int i;
@@ -543,7 +544,8 @@ classifier_replace(struct classifier *cls, const struct cls_rule *rule,
/* Compute hashes in segments. */
basis = 0;
mask_offset = 0;
for (i = 0; i < subtable->n_indices; i++) {
n_indices = subtable->n_indices;
for (i = 0; i < n_indices; i++) {
ihash[i] = minimatch_hash_range(&rule->match, subtable->index_maps[i],
&mask_offset, &basis);
}
@@ -575,7 +577,7 @@ classifier_replace(struct classifier *cls, const struct cls_rule *rule,
}
/* Add new node to segment indices. */
for (i = 0; i < subtable->n_indices; i++) {
for (i = 0; i < n_indices; i++) {
ccmap_inc(&subtable->indices[i], ihash[i]);
}
n_rules = cmap_insert(&subtable->rules, &new->cmap_node, hash);
@@ -713,6 +715,7 @@ classifier_remove(struct classifier *cls, const struct cls_rule *cls_rule)
struct cls_subtable *subtable;
uint32_t basis = 0, hash, ihash[CLS_MAX_INDICES];
unsigned int mask_offset;
uint8_t n_indices;
size_t n_rules;
unsigned int i;
@@ -730,7 +733,8 @@ classifier_remove(struct classifier *cls, const struct cls_rule *cls_rule)
ovs_assert(subtable);
mask_offset = 0;
for (i = 0; i < subtable->n_indices; i++) {
n_indices = subtable->n_indices;
for (i = 0; i < n_indices; i++) {
ihash[i] = minimatch_hash_range(&cls_rule->match,
subtable->index_maps[i],
&mask_offset, &basis);
@@ -783,7 +787,7 @@ classifier_remove(struct classifier *cls, const struct cls_rule *cls_rule)
}
/* Remove rule node from indices. */
for (i = 0; i < subtable->n_indices; i++) {
for (i = 0; i < n_indices; i++) {
ccmap_dec(&subtable->indices[i], ihash[i]);
}
n_rules = cmap_remove(&subtable->rules, &rule->cmap_node, hash);