Bluetooth: Host: ACL/ISO buffers and bt_conn_tx objects mismatch

doc/releases/release-notes-4.2.rst

@@ -103,6 +103,10 @@ Deprecated APIs and options
   deprecated, because support for anonymous authentication had been removed from the
   hawkBit server in version 0.8.0.
 
+* The :kconfig:option:`CONFIG_BT_CONN_TX_MAX` Kconfig option has been deprecated. The number of
+  pending TX buffers is now aligned with the :kconfig:option:`CONFIG_BT_BUF_ACL_TX_COUNT` Kconfig
+  option.
+
 New APIs and options
 ====================
 

include/zephyr/bluetooth/gatt.h

@@ -1383,8 +1383,6 @@ struct bt_gatt_notify_params {
  *  The callback is run from System Workqueue context.
  *  When called from the System Workqueue context this API will not wait for
  *  resources for the callback but instead return an error.
- *  The number of pending callbacks can be increased with the
- *  @kconfig{CONFIG_BT_CONN_TX_MAX} option.
  *
  *  Alternatively it is possible to notify by UUID by setting it on the
  *  parameters, when using this method the attribute if provided is used as the
@@ -2078,8 +2076,6 @@ int bt_gatt_write(struct bt_conn *conn, struct bt_gatt_write_params *params);
  *  The callback is run from System Workqueue context.
  *  When called from the System Workqueue context this API will not wait for
  *  resources for the callback but instead return an error.
- *  The number of pending callbacks can be increased with the
- *  @kconfig{CONFIG_BT_CONN_TX_MAX} option.
  *
  *  @param conn Connection object.
  *  @param handle Attribute handle.

subsys/bluetooth/host/Kconfig

@@ -326,7 +326,7 @@ config BT_CONN_FRAG_COUNT
 if BT_CONN
 
 config BT_CONN_TX_MAX
-	int "Maximum number of pending TX buffers with a callback"
+	int "Maximum number of pending TX buffers with a callback [DEPRECATED]"
 	default BT_BUF_ACL_TX_COUNT
 	range BT_BUF_ACL_TX_COUNT $(UINT8_MAX)
 	help

subsys/bluetooth/host/classic/Kconfig

@@ -140,8 +140,8 @@ config BT_RFCOMM_L2CAP_MTU
 
 config BT_RFCOMM_TX_MAX
 	int "Maximum number of pending TX buffers for RFCOMM"
-	default BT_CONN_TX_MAX
-	range BT_CONN_TX_MAX $(UINT8_MAX)
+	default BT_BUF_ACL_TX_COUNT
+	range BT_BUF_ACL_TX_COUNT $(UINT8_MAX)
 	help
 	  Maximum number of pending TX buffers that have an associated
 	  sending buf. Normally this can be left to the default value, which

subsys/bluetooth/host/conn.c

@@ -120,7 +120,7 @@ sys_slist_t bt_auth_info_cbs = SYS_SLIST_STATIC_INIT(&bt_auth_info_cbs);
 
 static sys_slist_t conn_cbs = SYS_SLIST_STATIC_INIT(&conn_cbs);
 
-static struct bt_conn_tx conn_tx[CONFIG_BT_CONN_TX_MAX];
+static struct bt_conn_tx conn_tx[CONFIG_BT_BUF_ACL_TX_COUNT];
 
 #if defined(CONFIG_BT_CLASSIC)
 static struct bt_conn sco_conns[CONFIG_BT_MAX_SCO_CONN];

subsys/bluetooth/host/hci_core.c

@@ -92,6 +92,26 @@
 #define BT_HCI_QUIRKS 0
 #endif
 
+/* These checks are added to warn if the number of ACL or ISO packets in Controller is not equal to
+ * the number of bt_conn_tx contexts allocated by Host. The inequality of these two values can lead
+ * to inefficient resources usage either on Host's or Controller's side.
+ */
+#define CHECK_NUM_OF_ACL_PKTS(_num) \
+	do { \
+		if (CONFIG_BT_BUF_ACL_TX_COUNT != (_num)) { \
+			LOG_WRN("Num of Controller's ACL packets != ACL bt_conn_tx contexts" \
+				" (%u != %u)", (_num), CONFIG_BT_BUF_ACL_TX_COUNT); \
+		} \
+	} while (0)
+
+#define CHECK_NUM_OF_ISO_PKTS(_num) \
+	do { \
+		if (CONFIG_BT_ISO_TX_BUF_COUNT != (_num)) { \
+			LOG_WRN("Num of Controller's ISO packets != ISO bt_conn_tx contexts" \
+				"(%u != %u)", (_num), CONFIG_BT_ISO_TX_BUF_COUNT); \
+		} \
+	} while (0)
+
 void bt_tx_irq_raise(void);
 
 #define HCI_CMD_TIMEOUT      K_SECONDS(10)
@@ -3159,6 +3179,8 @@
 
 	LOG_DBG("ACL LE buffers: pkts %u mtu %u", rp->le_max_num, bt_dev.le.acl_mtu);
 
+	CHECK_NUM_OF_ACL_PKTS(rp->le_max_num);
+
 	k_sem_init(&bt_dev.le.acl_pkts, rp->le_max_num, rp->le_max_num);
 #endif /* CONFIG_BT_CONN */
 }
@@ -3178,6 +3200,8 @@
 		LOG_DBG("ACL LE buffers: pkts %u mtu %u", rp->acl_max_num, bt_dev.le.acl_mtu);
 
 		k_sem_init(&bt_dev.le.acl_pkts, rp->acl_max_num, rp->acl_max_num);
+
+		CHECK_NUM_OF_ACL_PKTS(rp->acl_max_num);
 	}
 #endif /* CONFIG_BT_CONN */
 
@@ -3194,6 +3218,8 @@
 
 	k_sem_init(&bt_dev.le.iso_pkts, rp->iso_max_num, rp->iso_max_num);
 	bt_dev.le.iso_limit = rp->iso_max_num;
+
+	CHECK_NUM_OF_ISO_PKTS(rp->iso_max_num);
 #endif /* CONFIG_BT_ISO */
 }
 

tests/bluetooth/host/conn/prj.conf

@@ -12,7 +12,6 @@ CONFIG_BT_PER_ADV_SYNC=y
 
 CONFIG_BT_MAX_CONN=1
 CONFIG_BT_L2CAP_TX_MTU=23
-CONFIG_BT_CONN_TX_MAX=3
 CONFIG_BT_CONN_PARAM_UPDATE_TIMEOUT=5000
 CONFIG_BT_L2CAP_TX_BUF_COUNT=3
 CONFIG_BT_ID_MAX=1

tests/bsim/bluetooth/host/l2cap/stress/prj.conf

@@ -32,7 +32,7 @@ CONFIG_BT_BUF_ACL_TX_COUNT=4
 # L2AP MPS + L2CAP header (4)
 CONFIG_BT_BUF_ACL_RX_SIZE=81
 
-# Governs BT_CONN_TX_MAX, and so must be >= than the max number of
+# Governs CONFIG_BT_BUF_ACL_TX_COUNT, and so must be >= than the max number of
 # peers, since we attempt to send one SDU per peer. The test execution
 # is a bit slowed down by having this at the very minimum, but we want
 # to keep it that way as to stress the stack as much as possible.

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

@@ -26,10 +26,6 @@ CONFIG_BT_GAP_AUTO_UPDATE_CONN_PARAMS=n
 
 CONFIG_BT_MAX_CONN=1
 
-# We don't want to be constrained on the number of TX
-# contexts, rather on the number of LL TX buffers.
-CONFIG_BT_CONN_TX_MAX=10
-
 # Outgoing ATT buffers
 CONFIG_BT_ATT_TX_COUNT=1