On Wed, Oct 18, 2023 at 1:58 PM Jacob Satterfield
<jsatterfield.linux@xxxxxxxxx> wrote:
>
> Similar to the list_for_each macros in list.h, this patch adds two
> macros that iterates an avtab_node linked list (avtab_chain_for_each and
> avtab_chain_for_each_prev). This has two benefits: it reduces the amount
> of duplicative code for iteration and it makes changes to the underlying
> hashtable data structure easier as there are fewer places to update.
>
> Signed-off-by: Jacob Satterfield <jsatterfield.linux@xxxxxxxxx>
> ---
> security/selinux/ss/avtab.c | 28 ++++++++++++----------------
> 1 file changed, 12 insertions(+), 16 deletions(-)
>
> diff --git a/security/selinux/ss/avtab.c b/security/selinux/ss/avtab.c
> index 697eb4352439..f0d448e7807a 100644
> --- a/security/selinux/ss/avtab.c
> +++ b/security/selinux/ss/avtab.c
> @@ -27,6 +27,13 @@
> static struct kmem_cache *avtab_node_cachep __ro_after_init;
> static struct kmem_cache *avtab_xperms_cachep __ro_after_init;
>
> +#define avtab_chain_for_each(pos, tab, slot) \
> + for (pos = (tab)->htable[slot]; pos; pos = pos->next)
> +
> +#define avtab_chain_for_each_prev(pos, prev, tab, slot) \
> + for (prev = NULL, pos = (tab)->htable[slot]; pos; \
> + prev = pos, pos = pos->next)
> +
> /* Based on MurmurHash3, written by Austin Appleby and placed in the
> * public domain.
> */
> @@ -129,9 +136,7 @@ static int avtab_insert(struct avtab *h, const struct avtab_key *key,
> return -EINVAL;
>
> hvalue = avtab_hash(key, h->mask);
> - for (prev = NULL, cur = h->htable[hvalue];
> - cur;
> - prev = cur, cur = cur->next) {
> + avtab_chain_for_each_prev(cur, prev, h, hvalue) {
> cmp = avtab_node_cmp(key, &cur->key);
> /* extended perms may not be unique */
> if (cmp == 0 && !(key->specified & AVTAB_XPERMS))
> @@ -163,9 +168,7 @@ struct avtab_node *avtab_insert_nonunique(struct avtab *h,
> if (!h || !h->nslot || h->nel == U32_MAX)
> return NULL;
> hvalue = avtab_hash(key, h->mask);
> - for (prev = NULL, cur = h->htable[hvalue];
> - cur;
> - prev = cur, cur = cur->next) {
> + avtab_chain_for_each_prev(cur, prev, h, hvalue) {
> cmp = avtab_node_cmp(key, &cur->key);
> if (cmp <= 0)
> break;
> @@ -180,16 +183,13 @@ struct avtab_node *avtab_insert_nonunique(struct avtab *h,
> struct avtab_node *avtab_search_node(struct avtab *h,
> const struct avtab_key *key)
> {
> - u32 hvalue;
> struct avtab_node *cur;
> int cmp;
>
> if (!h || !h->nslot)
> return NULL;
>
> - hvalue = avtab_hash(key, h->mask);
> - for (cur = h->htable[hvalue]; cur;
> - cur = cur->next) {
> + avtab_chain_for_each(cur, h, avtab_hash(key, h->mask)) {
> cmp = avtab_node_cmp(key, &cur->key);
> if (cmp == 0)
> return cur;
> @@ -229,7 +229,6 @@ void avtab_destroy(struct avtab *h)
> return;
>
> for (i = 0; i < h->nslot; i++) {
> - cur = h->htable[i];
This line can't be deleted. It will be restored in the next spin.
> while (cur) {
> temp = cur;
> cur = cur->next;
> @@ -307,10 +306,8 @@ void avtab_hash_eval(struct avtab *h, const char *tag)
> if (cur) {
> slots_used++;
> chain_len = 0;
> - while (cur) {
> + avtab_chain_for_each(cur, h, i)
> chain_len++;
> - cur = cur->next;
> - }
>
> if (chain_len > max_chain_len)
> max_chain_len = chain_len;
> @@ -593,8 +590,7 @@ int avtab_write(struct policydb *p, struct avtab *a, void *fp)
> return rc;
>
> for (i = 0; i < a->nslot; i++) {
> - for (cur = a->htable[i]; cur;
> - cur = cur->next) {
> + avtab_chain_for_each(cur, a, i) {
> rc = avtab_write_item(p, cur, fp);
> if (rc)
> return rc;
> --
> 2.41.0
>
