Bluetooth: Rename num_complete_pool -> sync_evt_pool

Refactor only. The surrounding ifdefs are intentionally not changed in
this patch. They will be in the near future.

Rename the pool and generalize the documentation to allow using this
pool for other events that fit the same criteria. This pool can be used
for any buffer that is processed synchronously, without negatively
affecting 'num complete' messages. E.g. 'cmd complete/status' can be put
in this pool already.

We will be working towards making the host process all event buffers
synchronously. This is because events have no dedicated flow control,
and discarding events in the driver without informing the host creates
problems. Discarding should instead happen in the host higher layers
when unavoidable.

Signed-off-by: Aleksander Wasaznik <[email protected]>
(cherry picked from commit 2a7adae)
Signed-off-by: Vinayak Kariappa Chettimada <[email protected]>

Author: alwa-nordic

subsys/bluetooth/host/buf.c

@@ -28,13 +28,17 @@
 #define NUM_COMLETE_EVENT_SIZE BT_BUF_EVT_SIZE(                        \
 	sizeof(struct bt_hci_cp_host_num_completed_packets) +          \
 	MAX_EVENT_COUNT * sizeof(struct bt_hci_handle_count))
-/* Dedicated pool for HCI_Number_of_Completed_Packets. This event is always
- * consumed synchronously by bt_recv_prio() so a single buffer is enough.
- * Having a dedicated pool for it ensures that exhaustion of the RX pool
- * cannot block the delivery of this priority event.
+
+/* Pool for RX HCI buffers that are always freed by `bt_recv`
+ * before it returns.
+ *
+ * A singleton buffer shall be sufficient for correct operation.
+ * The buffer count may be increased as an optimization to allow
+ * the HCI transport to fill buffers in parallel with `bt_recv`
+ * consuming them.
  */
-NET_BUF_POOL_FIXED_DEFINE(num_complete_pool, 1, NUM_COMLETE_EVENT_SIZE,
-			  sizeof(struct bt_buf_data), NULL);
+#define SYNC_EVT_SIZE NUM_COMLETE_EVENT_SIZE
+NET_BUF_POOL_FIXED_DEFINE(sync_evt_pool, 1, SYNC_EVT_SIZE, sizeof(struct bt_buf_data), NULL);
 #endif /* CONFIG_BT_CONN || CONFIG_BT_ISO */
 
 NET_BUF_POOL_FIXED_DEFINE(discardable_pool, CONFIG_BT_BUF_EVT_DISCARDABLE_COUNT,
@@ -92,7 +96,7 @@ struct net_buf *bt_buf_get_evt(uint8_t evt, bool discardable,
 	switch (evt) {
 #if defined(CONFIG_BT_CONN) || defined(CONFIG_BT_ISO)
 	case BT_HCI_EVT_NUM_COMPLETED_PACKETS:
-		buf = net_buf_alloc(&num_complete_pool, timeout);
+		buf = net_buf_alloc(&sync_evt_pool, timeout);
 		break;
 #endif /* CONFIG_BT_CONN || CONFIG_BT_ISO */
 	default:
@@ -139,7 +143,7 @@ struct net_buf_pool *bt_buf_get_discardable_pool(void)
 #if defined(CONFIG_BT_CONN) || defined(CONFIG_BT_ISO)
 struct net_buf_pool *bt_buf_get_num_complete_pool(void)
 {
-	return &num_complete_pool;
+	return &sync_evt_pool;
 }
 #endif /* CONFIG_BT_CONN || CONFIG_BT_ISO */
 #endif /* ZTEST_UNITTEST */