Is the lock released too early during reference count decrement?

[S-Maple]

Hi ,
I've been reading through your code and have a question about the reference counting implementation:
`void ref_release(void *ptr)
{
obj_t *obj;
char *cptr;
int dofree = 0;

cptr = (char *)ptr;
cptr -= sizeof(obj_t);
obj = (obj_t *)cptr;

pthread_mutex_lock(&obj->mutex);
if (--obj->ref == 0) {
dofree = 1;
}
pthread_mutex_unlock(&obj->mutex);
if (dofree) {
pthread_mutex_destroy(&obj->mutex);
free(obj);
}
}`
The current implementation releases the lock immediately after decrementing the reference count. Could this lead to a race condition?

Scenario I'm worried about:
Thread A calls ref_release(), decrements the count to 0, sets dofree = 1, then releases the lock.Before Thread A does free(), Thread B calls ref_retain().Thread B successfully acquires the lock, increments the reference count, and returns.Thread A then proceeds to destroy the mutex and free the memory.Thread B now holds a dangling pointer to freed memory
Would it be safer to hold the lock until after the destruction/free operations are complete? Or is there another synchronization mechanism ensuring this can't happen?
Thanks for your time!