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authorMaria Matejka <mq@ucw.cz>2021-05-24 13:41:23 +0200
committerMaria Matejka <mq@ucw.cz>2021-11-22 19:05:43 +0100
commitdf3264f51ff38c9366398564a9d342a26bc83f37 (patch)
tree449ae9b631b57f867cc01dd4b6e8de63bbc30045 /sysdep/unix/coroutine.c
parent1289c1c5eede5b3d015d06b725d30024ccac51bd (diff)
Lock position checking allows for safe lock unions
Diffstat (limited to 'sysdep/unix/coroutine.c')
-rw-r--r--sysdep/unix/coroutine.c22
1 files changed, 15 insertions, 7 deletions
diff --git a/sysdep/unix/coroutine.c b/sysdep/unix/coroutine.c
index 71847505..2eba142c 100644
--- a/sysdep/unix/coroutine.c
+++ b/sysdep/unix/coroutine.c
@@ -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))