tests: Bluetooth: add babblesim connection stress test

This is supposed to stress the host buffer and metadata handling.

It is not really testing any particular thing, ie. the pass criteria is
just that each peripheral can send and receive a fixed number of GATT
notifications without any device crashing or locking up.

Original version by Ahmed Moheib (from cloud2ground).

Signed-off-by: Jonathan Rico <[email protected]>

tests/bsim/bluetooth/host/compile.sh

@@ -71,6 +71,8 @@ app=tests/bsim/bluetooth/host/l2cap/send_on_connect conf_file=prj_ecred.conf com
 app=tests/bsim/bluetooth/host/misc/disable compile
 app=tests/bsim/bluetooth/host/misc/disconnect/dut compile
 app=tests/bsim/bluetooth/host/misc/disconnect/tester compile
+app=tests/bsim/bluetooth/host/misc/conn_stress/central compile
+app=tests/bsim/bluetooth/host/misc/conn_stress/peripheral compile
 
 app=tests/bsim/bluetooth/host/privacy/central compile
 app=tests/bsim/bluetooth/host/privacy/peripheral compile

tests/bsim/bluetooth/host/misc/conn_stress/central/CMakeLists.txt

@@ -0,0 +1,15 @@
+# SPDX-License-Identifier: Apache-2.0
+
+cmake_minimum_required(VERSION 3.20.0)
+
+find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})
+project(conn_stress_central)
+
+target_sources(app PRIVATE
+  src/main.c
+)
+
+zephyr_include_directories(
+  $ENV{BSIM_COMPONENTS_PATH}/libUtilv1/src/
+  $ENV{BSIM_COMPONENTS_PATH}/libPhyComv1/src/
+)

tests/bsim/bluetooth/host/misc/conn_stress/central/prj.conf

@@ -0,0 +1,43 @@
+CONFIG_BT=y
+CONFIG_BT_DEBUG_LOG=y
+CONFIG_BT_CENTRAL=y
+CONFIG_BT_MAX_CONN=12
+CONFIG_BT_MAX_PAIRED=12
+CONFIG_BT_SMP=y
+CONFIG_BT_PRIVACY=y
+CONFIG_BT_GATT_CLIENT=y
+
+CONFIG_BT_CTLR_DATA_LENGTH_MAX=251
+CONFIG_BT_BUF_ACL_RX_SIZE=251
+CONFIG_BT_BUF_ACL_TX_SIZE=251
+
+CONFIG_BT_L2CAP_TX_MTU=247
+
+# variations of this =n or =y on central/per produce different errors
+CONFIG_BT_AUTO_PHY_UPDATE=y
+CONFIG_BT_AUTO_DATA_LEN_UPDATE=y
+
+CONFIG_ASSERT=y
+CONFIG_ASSERT_LEVEL=2
+CONFIG_ASSERT_VERBOSE=y
+CONFIG_ASSERT_ON_ERRORS=y
+
+# TODO: use default 3
+# we get an ATT timeout if 3
+# we get an SMP timeout if 10
+# CONFIG_BT_L2CAP_TX_BUF_COUNT=10
+
+# deadlock on central with the default.
+# the problem is that `tx_free` is called from both syswq and btwq in that case.
+CONFIG_BT_RECV_WORKQ_BT=y
+# CONFIG_BT_RECV_WORKQ_SYS=y
+
+# errors out getting event flags in hci_core.c
+# CONFIG_BT_RECV_BLOCKING=y
+
+# TODO: remove when test is stable
+CONFIG_BT_AUTO_PHY_UPDATE=n
+CONFIG_BT_AUTO_DATA_LEN_UPDATE=n
+CONFIG_BT_GAP_AUTO_UPDATE_CONN_PARAMS=n
+
+CONFIG_THREAD_NAME=y