Messages in this thread | | | Date | Fri, 15 Sep 2006 09:51:46 -0400 | From | "Dmitry Torokhov" <> | Subject | Re: [PATCH 0/3] Synaptics - fix lockdep warnings |
| |
On 9/15/06, Jiri Kosina <jikos@jikos.cz> wrote: > On Fri, 15 Sep 2006, Dmitry Torokhov wrote: > > > I understand what Ingo is saying about detecting deadlocks across the > > pool of locks of the same class not waiting till they really clash, it > > is really useful. I also want to make my code as independent of lockdep > > as possible. Having a speciall marking on the locks themselves (done > > upon creation) instead of altering call sites is the cleanest way IMHO. > > Can we have a flag in the lock structure that would tell lockdep that it > > is OK for the given lock to be taken several times (i.e. the locks are > > really on the different objects)? This would still allow to detect > > incorrect locking across different classes. > > Yes, but unfortunately marking the lock as 'can-be-taken-multiple-times' > is weaker than using the nested locking provided by lockdep. > > i.e. if you mark a lock this way, it opens door for having deadlock, which > won't be detected by lockdep. This will happen if the code, by mistake, > really takes the _very same_ lock twice. lockdep will not be able to > detect this, when the lock is marked in a way you propose, but is able to > detect this when using the nested semantics. >
But nested semantics breaks the notion of the locks belonging to the same pool so both solutions have tradeoffs. I could use either one of these as long as details are hidden and callers do not have to care.
-- Dmitry - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |