Lock position checking allows for safe lock unions (df3264f5) · Commits · 戴 / Bird

lib/locking.h

+2 −4

Original line number	Diff line number	Diff line
		@@ -16,16 +16,14 @@ struct lock_order {
		struct domain_generic *the_bird;
		};

		#define LOCK_ORDER_DEPTH (sizeof(struct lock_order) / sizeof(struct domain_generic *))

		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_NEW(type, name) (DOMAIN(type)) { .type = domain_new(name) }
		struct domain_generic domain_new(const char name);
		#define DOMAIN_NEW(type, name) (DOMAIN(type)) { .type = domain_new(name, OFFSETOF(struct lock_order, type)) }
		struct domain_generic domain_new(const char name, uint order);

		#define DOMAIN_NULL(type) (DOMAIN(type)) {}

sysdep/unix/coroutine.c

+15 −7

Original line number	Diff line number	Diff line
		@@ -44,26 +44,31 @@
		* Locking subsystem
		*/

		_Thread_local struct lock_order locking_stack = {};
		_Thread_local struct domain_generic **last_locked = NULL;

		#define ASSERT_NO_LOCK ASSERT_DIE(last_locked == NULL)

		struct domain_generic {
		pthread_mutex_t mutex;
		uint order;
		struct domain_generic **prev;
		struct lock_order *locked_by;
		const char *name;
		};

		#define DOMAIN_INIT(_name) { .mutex = PTHREAD_MUTEX_INITIALIZER, .name = _name }
		#define DOMAIN_INIT(_name, _order) { .mutex = PTHREAD_MUTEX_INITIALIZER, .name = _name, .order = _order }

		static struct domain_generic the_bird_domain_gen = DOMAIN_INIT("The BIRD");
		static struct domain_generic the_bird_domain_gen = DOMAIN_INIT("The BIRD", OFFSETOF(struct lock_order, the_bird));

		DOMAIN(the_bird) the_bird_domain = { .the_bird = &the_bird_domain_gen };

		struct domain_generic *
		domain_new(const char *name)
		domain_new(const char *name, uint order)
		{
		ASSERT_DIE(order < sizeof(struct lock_order));
		struct domain_generic *dg = xmalloc(sizeof(struct domain_generic));
		*dg = (struct domain_generic) DOMAIN_INIT(name);
		*dg = (struct domain_generic) DOMAIN_INIT(name, order);
		return dg;
		}

		@@ -74,11 +79,11 @@ domain_free(struct domain_generic *dg)
		xfree(dg);
		}

		_Thread_local struct lock_order locking_stack = {};
		_Thread_local struct domain_generic **last_locked = NULL;

		void do_lock(struct domain_generic dg, struct domain_generic *lsp)
		{
		if ((char ) lsp - (char ) &locking_stack != dg->order)
		bug("Trying to lock on bad position: order=%u, lsp=%p, base=%p", dg->order, lsp, &locking_stack);

		if (lsp <= last_locked)
		bug("Trying to lock in a bad order");
		if (*lsp)
		@@ -96,6 +101,9 @@ void do_lock(struct domain_generic dg, struct domain_generic *lsp)

		void do_unlock(struct domain_generic dg, struct domain_generic *lsp)
		{
		if ((char ) lsp - (char ) &locking_stack != dg->order)
		bug("Trying to unlock on bad position: order=%u, lsp=%p, base=%p", dg->order, lsp, &locking_stack);

		if (dg->locked_by != &locking_stack)
		bug("Inconsistent domain state on unlock");
		if ((last_locked != lsp) \|\| (*lsp != dg))

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