On Sat, 2007-12-08 at 00:02 +0100, Remy Bohmer wrote: > Hello Peter, > > > > What specifically is wrong with dev->sem ? > > > > Nothing really, other than that they use semaphores to avoid lockdep :-/ > > > > I think I know how to annotate this, after Alan Stern explained all the > > use cases, but I haven't come around to implementing it. Hope to do that > > soonish. > > I was looking for an easy semaphore I could convert to a mutex, and I > ran into one that was widely spread and interesting, and which seemed > quite doable at first sight. > So, I started working on it, but was forgotten this discussion, (until > Daniel made me remember it this afternoon). So, I (stupid me ;-) ) > tried to convert dev->sem... > > After doing the monkey part of the conversion I can boot the kernel > completely on X86 and ARM, and everything works fine, except after > enabling lockdep, lockdep starts complaining... > > Is this the problem you were pointing at?
Yeah, one of the interesting nestings :-) > I tried debugging it, and I have not found a recursive mutex locking > so far, only locking of 2 different mutexes in a row prior to this > warning, which IMO should be valid. > > What is your opinion? Yeah, the locking is all valid afaics, its just that it needs some interesting annotations to make lockdep see it that way. > BTW: I attached my patch for dev->sem as I have it now, that generates > this lockdep warning ( for if you want to look at it yourself also, so > you do not have to do the monkey part yourself anymore ;-) I have a similar patch floating around, but thanks anyway :-) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
