1 files changed, 70 insertions, 0 deletions
diff --git a/lib/locking.h b/lib/locking.h
new file mode 100644
index 00000000..6bed14bf
--- /dev/null
+++ b/lib/locking.h
@@ -0,0 +1,70 @@
+/*
+ *	BIRD Library -- Locking
+ *
+ *	(c) 2020--2021 Maria Matejka <mq@jmq.cz>
+ *
+ *	Can be freely distributed and used under the terms of the GNU GPL.
+ */
+
+#ifndef _BIRD_LOCKING_H_
+#define _BIRD_LOCKING_H_
+
+struct domain_generic;
+
+/* Here define the global lock order; first to last. */
+struct lock_order {
+  struct domain_generic *meta;
+  struct domain_generic *the_bird;
+  struct domain_generic *control;
+  struct domain_generic *proto;
+  struct domain_generic *service;
+  struct domain_generic *rtable;
+  struct domain_generic *attrs;
+  struct domain_generic *resource;
+};
+
+extern _Thread_local struct lock_order locking_stack;
+extern _Thread_local struct domain_generic **last_locked;
+
+#define DOMAIN(type) struct domain__##type
+#define DEFINE_DOMAIN(type) DOMAIN(type) { struct domain_generic *type; }
+#define DOMAIN_ORDER(type)  OFFSETOF(struct lock_order, type)
+
+#define DOMAIN_NEW(type, name)  (DOMAIN(type)) { .type = domain_new(name, DOMAIN_ORDER(type)) }
+struct domain_generic *domain_new(const char *name, uint order);
+
+#define DOMAIN_FREE(type, d)	domain_free((d).type)
+void domain_free(struct domain_generic *);
+
+#define DOMAIN_NAME(type, d)	domain_name((d).type)
+const char *domain_name(struct domain_generic *);
+
+#define DOMAIN_NULL(type)   (DOMAIN(type)) {}
+
+#define LOCK_DOMAIN(type, d)	do_lock(((d).type), &(locking_stack.type))
+#define UNLOCK_DOMAIN(type, d)  do_unlock(((d).type), &(locking_stack.type))
+
+#define DOMAIN_IS_LOCKED(type, d) (((d).type) == (locking_stack.type))
+#define DG_IS_LOCKED(d)	((d) == *(DG_LSP(d)))
+
+/* Internal for locking */
+void do_lock(struct domain_generic *dg, struct domain_generic **lsp);
+void do_unlock(struct domain_generic *dg, struct domain_generic **lsp);
+
+uint dg_order(struct domain_generic *dg);
+
+#define DG_LSP(d)	((struct domain_generic **) (((void *) &locking_stack) + dg_order(d)))
+#define DG_LOCK(d)	do_lock(d, DG_LSP(d))
+#define DG_UNLOCK(d)	do_unlock(d, DG_LSP(d))
+
+/* Use with care. To be removed in near future. */
+DEFINE_DOMAIN(the_bird);
+extern DOMAIN(the_bird) the_bird_domain;
+
+#define the_bird_lock()		LOCK_DOMAIN(the_bird, the_bird_domain)
+#define the_bird_unlock()	UNLOCK_DOMAIN(the_bird, the_bird_domain)
+#define the_bird_locked()	DOMAIN_IS_LOCKED(the_bird, the_bird_domain)
+
+#define ASSERT_THE_BIRD_LOCKED	({ if (!the_bird_locked()) bug("The BIRD lock must be locked here: %s:%d", __FILE__, __LINE__); })
+
+#endif