On Fri, Dec 1, 2023 at 4:52 PM Waiman Long <longman@xxxxxxxxxx> wrote: > On 12/1/23 10:01, Jann Horn wrote: >> I think this pattern anyway only works when you're only trying to wait >> for the current holder of the lock, not tasks that are queued up on >> the lock as waiters - so a task initially holds a stable reference to >> some object, then acquires the object's lock, then drops the original >> reference, and then later drops the lock. >> You can see an example of such mutex usage (which is explicitly legal >> with userspace POSIX mutexes, but is forbidden with kernel mutexes) at >> the bottom of the POSIX manpage for pthread_mutex_destroy() at >> <https://pubs.opengroup.org/onlinepubs/007904875/functions/pthread_mutex_destroy.html>, >> in the section "Destroying Mutexes". > > The POSIX mutex is reference-counted. I don't understand what you mean by that. Anyway, I guess this thread of discussion is moot - I'm not suggesting that kernel mutexes should support this behavior.
