On Sat, 2007-12-08 at 13:16 +0100, Peter Zijlstra wrote: > 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 :-)
It must be the locking in __driver_attach(), taking dev->parent->sem then taking dev->sem .. Assuming those are different structures, why does lockdep trigger? Daniel -- 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/
