Bluetooth: Host: add unregister connection callback function

[Description]
tests: shell: Restart bt will register the same connection callback twice.
Callback next node point to itself, when link established callback function
loop infinitely.
[Fix]
Unregister the previous callback to avoid register repeatedly.
[Test]
After bt init/disable times, create connection successfully.

Signed-off-by: huajiang zheng <[email protected]>

include/zephyr/bluetooth/conn.h

@@ -1151,6 +1151,19 @@ struct bt_conn_cb {
  */
 void bt_conn_cb_register(struct bt_conn_cb *cb);
 
+/**
+ * @brief Unregister connection callbacks.
+ *
+ * Unregister the state of connections callbacks.
+ *
+ * @param cb Callback struct point to memory that remains valid.
+ *
+ * @retval 0 Success
+ * @retval -EINVAL If @p cb is NULL
+ * @retval -ENOENT if @p cb was not registered
+ */
+int bt_conn_cb_unregister(struct bt_conn_cb *cb);
+
 /**
  *  @brief Register a callback structure for connection events.
  *

subsys/bluetooth/host/conn.c

@@ -2339,6 +2339,33 @@ void bt_conn_cb_register(struct bt_conn_cb *cb)
 	callback_list = cb;
 }
 
+int bt_conn_cb_unregister(struct bt_conn_cb *cb)
+{
+	struct bt_conn_cb *previous_callback;
+
+	CHECKIF(cb == NULL) {
+		return -EINVAL;
+	}
+
+	if (callback_list == cb) {
+		callback_list = callback_list->_next;
+		return 0;
+	}
+
+	previous_callback = callback_list;
+
+	while (previous_callback->_next) {
+		if (previous_callback->_next == cb) {
+			previous_callback->_next = previous_callback->_next->_next;
+			return 0;
+		}
+
+		previous_callback = previous_callback->_next;
+	}
+
+	return -ENOENT;
+}
+
 bool bt_conn_exists_le(uint8_t id, const bt_addr_le_t *peer)
 {
 	struct bt_conn *conn = bt_conn_lookup_addr_le(id, peer);

subsys/bluetooth/shell/bt.c

@@ -1061,6 +1061,8 @@ static void bt_ready(int err)
 #if defined(CONFIG_BT_CONN)
 	default_conn = NULL;
 
+	/* Unregister to avoid register repeatedly */
+	bt_conn_cb_unregister(&conn_callbacks);
 	bt_conn_cb_register(&conn_callbacks);
 #endif /* CONFIG_BT_CONN */
 

tests/bsim/bluetooth/host/misc/unregister_conn_cb/CMakeLists.txt

@@ -0,0 +1,14 @@
+# SPDX-License-Identifier: Apache-2.0
+
+cmake_minimum_required(VERSION 3.20.0)
+
+find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})
+project(bsim_test_unregister_conn_cb)
+
+FILE(GLOB app_sources src/*.c)
+target_sources(app PRIVATE ${app_sources} )
+
+zephyr_include_directories(
+  ${BSIM_COMPONENTS_PATH}/libUtilv1/src/
+  ${BSIM_COMPONENTS_PATH}/libPhyComv1/src/
+  )

tests/bsim/bluetooth/host/misc/unregister_conn_cb/prj.conf

@@ -0,0 +1,4 @@
+CONFIG_BT=y
+CONFIG_BT_DEVICE_NAME="conn tester"
+CONFIG_BT_PERIPHERAL=y
+CONFIG_BT_CENTRAL=y

tests/bsim/bluetooth/host/misc/unregister_conn_cb/src/common.c

@@ -0,0 +1,20 @@
+/*
+ * Copyright (c) 2022 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include "common.h"
+
+void test_tick(bs_time_t HW_device_time)
+{
+	if (bst_result != Passed) {
+		FAIL("test failed (not passed after %i seconds)\n", WAIT_TIME);
+	}
+}
+
+void test_init(void)
+{
+	bst_ticker_set_next_tick_absolute(WAIT_TIME);
+	bst_result = In_progress;
+}

tests/bsim/bluetooth/host/misc/unregister_conn_cb/src/common.h

@@ -0,0 +1,55 @@
+/**
+ * Common functions and helpers for unregister connection callback tests
+ *
+ * Copyright (c) 2024 NXP
+ * Copyright (c) 2022 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <zephyr/kernel.h>
+
+#include "bs_types.h"
+#include "bs_tracing.h"
+#include "time_machine.h"
+#include "bstests.h"
+
+#include <zephyr/types.h>
+#include <stddef.h>
+#include <errno.h>
+
+#include <zephyr/bluetooth/bluetooth.h>
+#include <zephyr/bluetooth/hci.h>
+#include <zephyr/bluetooth/conn.h>
+
+extern enum bst_result_t bst_result;
+
+#define WAIT_SECONDS (30) /*seconds*/
+#define WAIT_TIME (WAIT_SECONDS * USEC_PER_SEC) /* microseconds*/
+
+#define CREATE_FLAG(flag) static atomic_t flag = (atomic_t) false
+#define SET_FLAG(flag)    (void)atomic_set(&flag, (atomic_t) true)
+#define UNSET_FLAG(flag)  (void)atomic_set(&flag, (atomic_t) false)
+#define WAIT_FOR_FLAG(flag)                                                                        \
+	while (!(bool)atomic_get(&flag)) {                                                         \
+		(void)k_sleep(K_MSEC(1));                                                          \
+	}
+#define WAIT_FOR_FLAG_UNSET(flag)                                                                  \
+	while ((bool)atomic_get(&flag)) {                                                          \
+		(void)k_sleep(K_MSEC(1));                                                          \
+	}
+
+#define FAIL(...)                                                                                  \
+	do {                                                                                       \
+		bst_result = Failed;                                                               \
+		bs_trace_error_time_line(__VA_ARGS__);                                             \
+	} while (0)
+
+#define PASS(...)                                                                                  \
+	do {                                                                                       \
+		bst_result = Passed;                                                               \
+		bs_trace_info_time(1, __VA_ARGS__);                                                \
+	} while (0)
+
+void test_tick(bs_time_t HW_device_time);
+void test_init(void);