On Saturday 12 December 2009, Alan Stern wrote: > On Sat, 12 Dec 2009, Rafael J. Wysocki wrote: > > > Below is a patch I've just tested, but there's a lockdep problem in it I don't > > know how to solve. Namely, lockdep is apparently unhappy with us not releasing > > the lock taken in device_suspend() and it complains we take it twice in a row > > (which we do, but for another device). I need to use down_read_non_owner() > > to make it shut up and then I also need to use up_read_non_owner() in > > __device_suspend(), although there's the comment in include/linux/rwsem.h > > saying exatly this about that: > > > > /* > > * Take/release a lock when not the owner will release it. > > * > > * [ This API should be avoided as much as possible - the > > * proper abstraction for this case is completions. ] > > */ > > > > (I'd like to know your opinion about that). Yet, that's not all, because next > > it complains during resume that __device_resume() releases a lock it didn't > > acquire, which it clearly does, but that is intentional. Unfortunately, > > there's no up_write_non_owner() ... > > Hah! I knew it! > > How come lockdep didn't complain earlier? What's different about this > patch? Only the nesting annotations? Why should adding annotations > make lockdep less happy? I'm not sure. Perhaps I made a mistake during the previous tests. Rafael -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
