Bluetooth: Host: Add BT_TESTING trace event for ACL pool destroy

This is needed for a test to catch a double-free.

Signed-off-by: Aleksander Wasaznik <[email protected]>

Author: alwa-nordic

include/zephyr/bluetooth/testing.h

@@ -0,0 +1,27 @@
+/* Copyright (c) 2024 Nordic Semiconductor ASA
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/** @brief Internal testing interfaces for Bluetooth
+ *  @file
+ *  @internal
+ *
+ *  The interfaces in this file are internal and not stable.
+ */
+
+#ifndef ZEPHYR_INCLUDE_BLUETOOTH_TESTING_H_
+#define ZEPHYR_INCLUDE_BLUETOOTH_TESTING_H_
+
+#include <zephyr/net_buf.h>
+
+/** @brief Hook for `acl_in_pool.destroy`
+ *
+ *  Weak-function interface. The user can simply define this
+ *  function, and it will automatically become the event
+ *  listener.
+ *
+ *  @kconfig_dep{CONFIG_BT_TESTING}
+ */
+void bt_testing_trace_event_acl_pool_destroy(struct net_buf *buf);
+
+#endif /* ZEPHYR_INCLUDE_BLUETOOTH_TESTING_H_ */

subsys/bluetooth/host/hci_core.c

@@ -14,6 +14,7 @@
 #include <zephyr/net_buf.h>
 #include <zephyr/sys/atomic.h>
 #include <zephyr/sys/check.h>
+#include <zephyr/sys/util_macro.h>
 #include <zephyr/sys/util.h>
 #include <zephyr/sys/slist.h>
 #include <zephyr/sys/byteorder.h>
@@ -28,6 +29,7 @@
 #include <zephyr/bluetooth/l2cap.h>
 #include <zephyr/bluetooth/hci.h>
 #include <zephyr/bluetooth/hci_vs.h>
+#include <zephyr/bluetooth/testing.h>
 #if DT_HAS_CHOSEN(zephyr_bt_hci)
 #include <zephyr/drivers/bluetooth.h>
 #else
@@ -263,13 +265,23 @@ void bt_send_one_host_num_completed_packets(uint16_t handle)
 	BT_ASSERT_MSG(err == 0, "Unable to send Host NCP (err %d)", err);
 }
 
+#if defined(CONFIG_BT_TESTING)
+__weak void bt_testing_trace_event_acl_pool_destroy(struct net_buf *buf)
+{
+}
+#endif
+
 #if defined(CONFIG_BT_HCI_ACL_FLOW_CONTROL)
 void bt_hci_host_num_completed_packets(struct net_buf *buf)
 {
 	uint16_t handle = acl(buf)->handle;
 	struct bt_conn *conn;
 	uint8_t index = acl(buf)->index;
 
+	if (IS_ENABLED(CONFIG_BT_TESTING)) {
+		bt_testing_trace_event_acl_pool_destroy(buf);
+	}
+
 	net_buf_destroy(buf);
 
 	if (acl(buf)->host_ncp_sent) {