On Thu, 2013-03-28 at 19:50 -0700, Michel Lespinasse wrote: > So, there are a few things I don't like about spin_unlock_wait(): > > 1- From a lock ordering point of view, it is strictly equivalent to > taking the lock and then releasing it - and yet, lockdep won't catch > any deadlocks that involve spin_unlock_wait. (Not your fault here, > this should be fixed as a separate change in lockdep. I manually > looked at the lock ordering here and found it safe).
Ooh, I never noticed that, but indeed this shouldn't be hard to cure. > 2- With the current ticket lock implementation, a stream of lockers > can starve spin_unlock_wait() forever. Once again, not your fault and > I suspect this could be fixed - I expect spin_unlock_wait() callers > actually only want to know that the lock has been passed on, not that > it actually got to an unlocked state. I suppose the question is do we want to fix it or have both semantics and use lock+unlock where appropriate. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
