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Use atomics to fix ASAN data races in critnib #1225

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Merged
merged 1 commit into from
Apr 15, 2025
Merged

Use atomics to fix ASAN data races in critnib #1225

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35 changes: 20 additions & 15 deletions src/critnib/critnib.c
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Original file line number Diff line number Diff line change
Expand Up @@ -246,8 +246,8 @@ static void free_node(struct critnib *__restrict c,
}

ASSERT(!is_leaf(n));
n->child[0] = c->deleted_node;
c->deleted_node = n;
utils_atomic_store_release_ptr((void **)&n->child[0], c->deleted_node);
utils_atomic_store_release_ptr((void **)&c->deleted_node, n);
}

/*
Expand Down Expand Up @@ -277,8 +277,8 @@ static void free_leaf(struct critnib *__restrict c,
return;
}

k->value = c->deleted_leaf;
c->deleted_leaf = k;
utils_atomic_store_release_ptr((void **)&k->value, c->deleted_leaf);
utils_atomic_store_release_ptr((void **)&c->deleted_leaf, k);
}

/*
Expand Down Expand Up @@ -319,8 +319,8 @@ int critnib_insert(struct critnib *c, word key, void *value, int update) {

utils_annotate_memory_no_check(k, sizeof(struct critnib_leaf));

k->key = key;
k->value = value;
utils_atomic_store_release_ptr((void **)&k->key, (void *)key);
utils_atomic_store_release_ptr((void **)&k->value, value);

struct critnib_node *kn = (void *)((word)k | 1);

Expand Down Expand Up @@ -358,7 +358,7 @@ int critnib_insert(struct critnib *c, word key, void *value, int update) {
free_leaf(c, to_leaf(kn));

if (update) {
to_leaf(n)->value = value;
utils_atomic_store_release_ptr(&to_leaf(n)->value, value);
utils_mutex_unlock(&c->mutex);
return 0;
} else {
Expand All @@ -381,13 +381,14 @@ int critnib_insert(struct critnib *c, word key, void *value, int update) {
utils_annotate_memory_no_check(m, sizeof(struct critnib_node));

for (int i = 0; i < SLNODES; i++) {
m->child[i] = NULL;
utils_atomic_store_release_ptr((void *)&m->child[i], NULL);
}

m->child[slice_index(key, sh)] = kn;
m->child[slice_index(path, sh)] = n;
utils_atomic_store_release_ptr((void *)&m->child[slice_index(key, sh)], kn);
utils_atomic_store_release_ptr((void *)&m->child[slice_index(path, sh)], n);
m->shift = sh;
m->path = key & path_mask(sh);
utils_atomic_store_release_u64((void *)&m->path, key & path_mask(sh));

utils_atomic_store_release_ptr((void **)parent, m);

utils_mutex_unlock(&c->mutex);
Expand Down Expand Up @@ -569,12 +570,15 @@ static struct critnib_leaf *find_le(struct critnib_node *__restrict n,
* that shift points at the nib's lower rather than upper edge, so it
* needs to be masked away as well.
*/
if ((key ^ n->path) >> (n->shift) & ~NIB) {
word path;
sh_t shift = n->shift;
utils_atomic_load_acquire_u64((uint64_t *)&n->path, (uint64_t *)&path);
if ((key ^ path) >> (shift) & ~NIB) {
/*
* subtree is too far to the left?
* -> its rightmost value is good
*/
if (n->path < key) {
if (path < key) {
return find_predecessor(n);
}

Expand Down Expand Up @@ -759,8 +763,9 @@ int critnib_find(struct critnib *c, uintptr_t key, enum find_dir_t dir,
k = (n && kk->key == key) ? kk : NULL;
}
if (k) {
_rkey = k->key;
_rvalue = k->value;
utils_atomic_load_acquire_u64((uint64_t *)&k->key,
(uint64_t *)&_rkey);
utils_atomic_load_acquire_ptr(&k->value, (void **)&_rvalue);
}
utils_atomic_load_acquire_u64(&c->remove_count, &wrs2);
} while (wrs1 + DELETED_LIFE <= wrs2);
Expand Down
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