Re: [PATCH v7 08/13] ksmbd: add smb3 engine part 1

+/**
+ * check_session_id() - check for valid session id in smb header
+ * @conn:	connection instance
+ * @id:		session id from smb header
+ *
+ * Return:      1 if valid session id, otherwise 0
+ */
+static inline int check_session_id(struct ksmbd_conn *conn, u64 id)

+{
+	struct ksmbd_session *sess;
+
+	if (id == 0 || id == -1)
+		return 0;
+
+	sess = ksmbd_session_lookup_all(conn, id);
+	if (sess)
+		return 1;
+	pr_err("Invalid user session id: %llu\n", id);
+	return 0;
+}
+
+struct channel *lookup_chann_list(struct ksmbd_session *sess, struct ksmbd_conn *conn)
+{
+	struct channel *chann;
+
+	list_for_each_entry(chann, &sess->ksmbd_chann_list, chann_list) {
+		if (chann->conn == conn)
+			return chann;
+	}
+
+	return NULL;
+}
+
+/**
+ * smb2_get_ksmbd_tcon() - get tree connection information for a tree id
+ * @work:	smb work
+ *
+ * Return:      matching tree connection on success, otherwise error

+ */
+int smb2_get_ksmbd_tcon(struct ksmbd_work *work)
+{
+	struct smb2_hdr *req_hdr = work->request_buf;
+	int tree_id;
+
+	work->tcon = NULL;
+	if (work->conn->ops->get_cmd_val(work) == SMB2_TREE_CONNECT_HE ||
+	    work->conn->ops->get_cmd_val(work) ==  SMB2_CANCEL_HE ||
+	    work->conn->ops->get_cmd_val(work) ==  SMB2_LOGOFF_HE) {
+		ksmbd_debug(SMB, "skip to check tree connect request\n");
+		return 0;
+	}
+
+	if (xa_empty(&work->sess->tree_conns)) {
+		ksmbd_debug(SMB, "NO tree connected\n");
+		return -1;

+	}
+
+	tree_id = le32_to_cpu(req_hdr->Id.SyncId.TreeId);
+	work->tcon = ksmbd_tree_conn_lookup(work->sess, tree_id);
+	if (!work->tcon) {
+		pr_err("Invalid tid %d\n", tree_id);
+		return -1;
+	}
+
+	return 1;
+}