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settings: zms: fix some bugs related to the name's ID

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To avoid collisions between IDs used by settings and IDs used directly
by subsystems using ZMS API, the MSB is always set to 1 for Setting's
name ID written to ZMS backend

Add as well a recovery path if the hash linked list is broken.

Signed-off-by: Riadh Ghaddab <rghaddab@baylibre.com>
This commit is contained in:
Riadh Ghaddab 2025-02-22 02:11:54 +01:00 committed by Fabio Baltieri
parent 91cf42c657
commit 333faddd43
2 changed files with 36 additions and 24 deletions
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3
subsys/settings/include/settings/settings_zms.h
View File

@ -60,10 +60,9 @@ extern "C" {
#define ZMS_COLLISIONS_MASK GENMASK(CONFIG_SETTINGS_ZMS_MAX_COLLISIONS_BITS, 1)
#define ZMS_HASH_TOTAL_MASK GENMASK(29, 1)
#define ZMS_MAX_COLLISIONS (BIT(CONFIG_SETTINGS_ZMS_MAX_COLLISIONS_BITS) - 1)
#define ZMS_HEADER_HASH 0x80000000
/* some useful macros */
#define ZMS_NAME_HASH_ID(x) (x & ZMS_HASH_TOTAL_MASK)
#define ZMS_NAME_ID_FROM_LL_NODE(x) (x & ~BIT(0))
#define ZMS_UPDATE_COLLISION_NUM(x, y) \
((x & ~ZMS_COLLISIONS_MASK) | ((y << 1) & ZMS_COLLISIONS_MASK))
#define ZMS_COLLISION_NUM(x) ((x & ZMS_COLLISIONS_MASK) >> 1)

57
subsys/settings/src/settings_zms.c
View File

@ -30,6 +30,7 @@ static int settings_zms_load(struct settings_store *cs, const struct settings_lo
static int settings_zms_save(struct settings_store *cs, const char *name, const char *value,
size_t val_len);
static void *settings_zms_storage_get(struct settings_store *cs);
static int settings_zms_get_last_hash_ids(struct settings_zms *cf);
static struct settings_store_itf settings_zms_itf = {.csi_load = settings_zms_load,
.csi_save = settings_zms_save,
@ -169,10 +170,11 @@ static int settings_zms_load(struct settings_store *cs, const struct settings_lo
* entries one for the setting's name and one with the
* setting's value.
*/
rc1 = zms_read(&cf->cf_zms, ZMS_NAME_HASH_ID(ll_hash_id), &name, sizeof(name) - 1);
rc1 = zms_read(&cf->cf_zms, ZMS_NAME_ID_FROM_LL_NODE(ll_hash_id), &name,
sizeof(name) - 1);
/* get the length of data and verify that it exists */
rc2 = zms_get_data_length(&cf->cf_zms,
ZMS_NAME_HASH_ID(ll_hash_id) + ZMS_DATA_ID_OFFSET);
rc2 = zms_get_data_length(&cf->cf_zms, ZMS_NAME_ID_FROM_LL_NODE(ll_hash_id) +
ZMS_DATA_ID_OFFSET);
if ((rc1 <= 0) || (rc2 <= 0)) {
/* Settings item is not stored correctly in the ZMS.
@ -180,7 +182,7 @@ static int settings_zms_load(struct settings_store *cs, const struct settings_lo
* or deleted. Clean dirty entries to make space for
* future settings item.
*/
ret = settings_zms_delete(cf, ZMS_NAME_HASH_ID(ll_hash_id));
ret = settings_zms_delete(cf, ZMS_NAME_ID_FROM_LL_NODE(ll_hash_id));
if (ret < 0) {
return ret;
}
@ -190,7 +192,7 @@ static int settings_zms_load(struct settings_store *cs, const struct settings_lo
/* Found a name, this might not include a trailing \0 */
name[rc1] = '\0';
read_fn_arg.fs = &cf->cf_zms;
read_fn_arg.id = ZMS_NAME_HASH_ID(ll_hash_id) + ZMS_DATA_ID_OFFSET;
read_fn_arg.id = ZMS_NAME_ID_FROM_LL_NODE(ll_hash_id) + ZMS_DATA_ID_OFFSET;
ret = settings_call_set_handler(name, rc2, settings_zms_read_fn, &read_fn_arg,
(void *)arg);
@ -232,8 +234,10 @@ static int settings_zms_save(struct settings_store *cs, const char *name, const
delete = ((value == NULL) || (val_len == 0));
name_hash = sys_hash32(name, strlen(name)) & ZMS_HASH_MASK;
/* MSB is always 1 */
name_hash |= BIT(31);
/* Let's find out if there is no hash collisions in the storage */
/* Let's find out if there are hash collisions in the storage */
write_name = true;
hash_collision = true;
@ -311,6 +315,16 @@ no_hash_collision:
}
/* write linked list structure element */
settings_element.next_hash = 0;
/* Verify first that the linked list last element is not broken.
* Settings subsystem uses ID that starts from ZMS_LL_HEAD_HASH_ID.
*/
if (cf->last_hash_id < ZMS_LL_HEAD_HASH_ID) {
LOG_WRN("Linked list for hashes is broken, Trying to recover");
rc = settings_zms_get_last_hash_ids(cf);
if (rc < 0) {
return rc;
}
}
settings_element.previous_hash = cf->last_hash_id;
rc = zms_write(&cf->cf_zms, name_hash | 1, &settings_element,
sizeof(struct settings_hash_linked_list));
@ -342,9 +356,22 @@ static int settings_zms_get_last_hash_ids(struct settings_zms *cf)
do {
rc = zms_read(&cf->cf_zms, ll_last_hash_id, &settings_element,
sizeof(settings_element));
if (rc) {
if (rc == -ENOENT) {
/* header doesn't exist or linked list broken, reinitialize the header */
const struct settings_hash_linked_list settings_element = {
.previous_hash = 0, .next_hash = 0};
rc = zms_write(&cf->cf_zms, ZMS_LL_HEAD_HASH_ID, &settings_element,
sizeof(struct settings_hash_linked_list));
if (rc < 0) {
return rc;
}
cf->last_hash_id = ZMS_LL_HEAD_HASH_ID;
cf->second_to_last_hash_id = 0;
return 0;
} else if (rc < 0) {
return rc;
}
/* increment hash collision number if necessary */
if (ZMS_COLLISION_NUM(ll_last_hash_id) > cf->hash_collision_num) {
cf->hash_collision_num = ZMS_COLLISION_NUM(ll_last_hash_id);
@ -375,23 +402,9 @@ static int settings_zms_backend_init(struct settings_zms *cf)
cf->hash_collision_num = 0;
rc = settings_zms_get_last_hash_ids(cf);
if (rc == -ENOENT) {
/* header doesn't exist or linked list broken, reinitialize the header */
const struct settings_hash_linked_list settings_element = {.previous_hash = 0,
.next_hash = 0};
rc = zms_write(&cf->cf_zms, ZMS_LL_HEAD_HASH_ID, &settings_element,
sizeof(struct settings_hash_linked_list));
if (rc < 0) {
return rc;
}
cf->last_hash_id = ZMS_LL_HEAD_HASH_ID;
cf->second_to_last_hash_id = 0;
} else if (rc < 0) {
return rc;
}
LOG_DBG("ZMS backend initialized");
return 0;
return rc;
}
int settings_backend_init(void)