subsys: fs: bm_zms: remove global callbacks array

Removes global callbacks array and replaces with callback
member inside `struct bm_zms_fs`.
This fixes a bug where registering multiple callbacks on
the same `struct bm_zms_fs` would update the user reference
number incrementally and saturate the global callbacks array.
When calling `bm_zms_clear`, this would only reset to NULL
the last callback set, leaving the rest still set.
This update makes it so that there can only be one callback
per each `struct bm_zms_fs` instance, mirroring the behavior
of other libraries.
Due to this change, also removes the `BM_ZMS_MAX_USERS`
Kconfig option.
Also removes the member `cb_registred` in the struct
`bm_zms_init_flags` since it is not used anymore.

Signed-off-by: Mirko Covizzi <mirko.covizzi@nordicsemi.no>

Author: MirkoCovizzi

doc/nrf-bm/release_notes/release_notes_changelog.rst

@@ -132,6 +132,9 @@ Libraries
      * The :c:func:`bm_zms_active_sector_free_space` function to return ``-EFAULT`` when the input parameter ``fs`` is ``NULL``.
      * The :c:func:`bm_zms_mount` function to expect an additional input parameter of type pointer to struct :c:struct:`bm_zms_fs_config` for configuring a Zephyr Memory Storage file system instance at initialization.
 
+   * Removed the :kconfig:option:`CONFIG_BM_ZMS_MAX_USERS` Kconfig option. Now the library expects at most one callback for each instance of the struct :c:struct:`bm_zms_fs`.
+   * Removed the :c:member:`bm_zms_init_flags.cb_registred` member since it was not used anymore.
+
 * :ref:`lib_peer_manager` library:
 
    * Updated:

include/bm/fs/bm_zms.h

@@ -25,7 +25,7 @@ extern "C" {
  */
 
 /**
- * @defgroup bm_zms_data_structures BM_ZMS data structures
+ * @defgroup bm_zms_data_types BM_ZMS data types
  * @ingroup bm_zms
  * @{
  */
@@ -60,9 +60,15 @@ typedef struct {
 struct bm_zms_init_flags {
 	volatile bool initialized;  /* true when the storage is initialized. */
 	volatile bool initializing; /* true when initialization is ongoing. */
-	bool cb_registred;	    /* true when the user callback is registred. */
 } __packed;
 
+/**
+ * @brief Bare Metal ZMS event handler function prototype.
+ *
+ * @param p_evt The event.
+ */
+typedef void (*bm_zms_cb_t)(bm_zms_evt_t const *p_evt);
+
 /** Zephyr Memory Storage file system structure */
 struct bm_zms_fs {
 	/** File system offset in flash. */
@@ -91,8 +97,8 @@ struct bm_zms_fs {
 	struct bm_storage zms_bm_storage;
 	/** Number of writes currently handled by the storage system. */
 	atomic_t ongoing_writes;
-	/** The user number that identifies the callback for an event. */
-	uint32_t user_num;
+	/** User callback for propagating events. */
+	bm_zms_cb_t user_cb;
 #if CONFIG_BM_ZMS_LOOKUP_CACHE
 	/** Lookup table used to cache ATE addresses of written IDs. */
 	uint64_t lookup_cache[CONFIG_BM_ZMS_LOOKUP_CACHE_SIZE];
@@ -121,13 +127,6 @@ struct bm_zms_fs_config {
  * @{
  */
 
-/**
- *@brief Bare Metal ZMS event handler function prototype.
- *
- * @param p_evt The event.
- */
-typedef void (*bm_zms_cb_t)(bm_zms_evt_t const *p_evt);
-
 /**
  * @brief Register a callback to BM_ZMS for handling events.
  *
@@ -136,7 +135,6 @@ typedef void (*bm_zms_cb_t)(bm_zms_evt_t const *p_evt);
  *
  * @retval 0 on success.
  * @retval -EFAULT if @p fs or @p cb are NULL.
- * @retval -ENOMEM if no more callback slots are available.
  */
 int bm_zms_register(struct bm_zms_fs *fs, bm_zms_cb_t cb);
 

subsys/fs/bm_zms/Kconfig

@@ -50,12 +50,6 @@ config BM_ZMS_CUSTOM_BLOCK_SIZE
 	help
 	  Changes the internal buffer size of BM_ZMS.
 
-config BM_ZMS_MAX_USERS
-	int "BM_ZMS maximum users"
-	default 8
-	help
-	  Defines the maximum number of event handlers that can be registred by the user.
-
 config BM_ZMS_OP_QUEUE_SIZE
 	int "BM_ZMS operations queue size"
 	default 16

subsys/fs/bm_zms/bm_zms.c

@@ -51,9 +51,6 @@ static int bm_zms_clear_execute(void);
  */
 static atomic_t queued_op_cnt;
 
-/* The table of app callback functions. */
-static bm_zms_cb_t zms_cb_table[CONFIG_BM_ZMS_MAX_USERS];
-
 /* Queue of bm_zms operations. */
 RING_BUF_DECLARE(zms_fifo, CONFIG_BM_ZMS_OP_QUEUE_SIZE * sizeof(zms_op_t));
 
@@ -97,8 +94,8 @@ static void event_prepare(bm_zms_evt_t *p_evt)
 
 static void event_send(bm_zms_evt_t const *const p_evt, struct bm_zms_fs *fs)
 {
-	if (zms_cb_table[fs->user_num] != NULL) {
-		zms_cb_table[fs->user_num](p_evt);
+	if (fs->user_cb != NULL) {
+		fs->user_cb(p_evt);
 	}
 }
 
@@ -188,7 +185,7 @@ static void queue_process(void)
 				/* bm_zms needs to be reinitialized after clearing */
 				cur_op.fs->init_flags.initialized = false;
 				cur_op.fs->init_flags.initializing = false;
-				zms_cb_table[cur_op.fs->user_num] = NULL;
+				cur_op.fs->user_cb = NULL;
 				cur_op.op_completed = true;
 				result = 0;
 			} else {
@@ -325,23 +322,11 @@ static void zms_event_handler(struct bm_storage_evt *p_evt)
 
 int bm_zms_register(struct bm_zms_fs *fs, bm_zms_cb_t cb)
 {
-	int i;
-
 	if (!fs || !cb) {
 		return -EFAULT;
 	}
 
-	for (i = 0; i < CONFIG_BM_ZMS_MAX_USERS; i++) {
-		if (zms_cb_table[i] == NULL) {
-			break;
-		}
-	}
-	if (i == CONFIG_BM_ZMS_MAX_USERS) {
-		return -ENOMEM;
-	}
-	zms_cb_table[i] = cb;
-	fs->user_num = i;
-	fs->init_flags.cb_registred = true;
+	fs->user_cb = cb;
 
 	return 0;
 }