Bluetooth: hci_sync: Fix not processing all entries on cmd_sync_work

hci_cmd_sync_queue can be called multiple times, each adding a
hci_cmd_sync_work_entry, before hci_cmd_sync_work is run so this makes
sure they are all dequeued properly otherwise it creates a backlog of
entries that are never run.

Link: https://lore.kernel.org/all/CAJCQCtSeUtHCgsHXLGrSTWKmyjaQDbDNpP4rb0i+RE+L2FTXSA@mail.gmail.com/T/
Fixes: 6a98e383 ("Bluetooth: Add helper for serialized HCI command execution")
Tested-by: Chris Clayton <chris2553@googlemail.com>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

net/bluetooth/hci_sync.c

@@ -276,41 +276,38 @@ EXPORT_SYMBOL(__hci_cmd_sync_status);
 static void hci_cmd_sync_work(struct work_struct *work)
 {
 	struct hci_dev *hdev = container_of(work, struct hci_dev, cmd_sync_work);
-	struct hci_cmd_sync_work_entry *entry;
-	hci_cmd_sync_work_func_t func;
-	hci_cmd_sync_work_destroy_t destroy;
-	void *data;
 
 	bt_dev_dbg(hdev, "");
 
+	/* Dequeue all entries and run them */
+	while (1) {
+		struct hci_cmd_sync_work_entry *entry;
+
 		mutex_lock(&hdev->cmd_sync_work_lock);
-	entry = list_first_entry(&hdev->cmd_sync_work_list,
-				 struct hci_cmd_sync_work_entry, list);
-	if (entry) {
+		entry = list_first_entry_or_null(&hdev->cmd_sync_work_list,
+						 struct hci_cmd_sync_work_entry,
+						 list);
+		if (entry)
 			list_del(&entry->list);
-		func = entry->func;
-		data = entry->data;
-		destroy = entry->destroy;
-		kfree(entry);
-	} else {
-		func = NULL;
-		data = NULL;
-		destroy = NULL;
-	}
 		mutex_unlock(&hdev->cmd_sync_work_lock);
 
-	if (func) {
-		int err;
-
-		hci_req_sync_lock(hdev);
+		if (!entry)
+			break;
 
-		err = func(hdev, data);
+		bt_dev_dbg(hdev, "entry %p", entry);
 
-		if (destroy)
-			destroy(hdev, data, err);
+		if (entry->func) {
+			int err;
 
+			hci_req_sync_lock(hdev);
+			err = entry->func(hdev, entry->data);
+			if (entry->destroy)
+				entry->destroy(hdev, entry->data, err);
 			hci_req_sync_unlock(hdev);
 		}
+
+		kfree(entry);
+	}
 }
 
 static void hci_cmd_sync_cancel_work(struct work_struct *work)