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Lock position checking allows for safe lock unions

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This commit is contained in:
Maria Matejka 2021-05-24 13:41:23 +02:00
parent 1289c1c5ee
commit df3264f51f
2 changed files with 17 additions and 11 deletions
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6
lib/locking.h
View File

@ -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)) {}

22
sysdep/unix/coroutine.c
View File

@ -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))