On Saturday, 2 December 2006 16:39, Alan Stern wrote: > On Sat, 2 Dec 2006, Pavel Machek wrote: > > > Hi! > > > > > > We send fake signals to them, so they enter get_signal_to_deliver() and they > > > > call try_to_freeze() from there. > > > > > > Well then, see, you're doing exactly what you said should never happen -- > > > you are freezing a user thread while it might be holding a lock that the > > > unfreezable usb-storage thread needs. > > > > > > I do not think it is okay to call get_signal_to_deliver with *any* > > lock held... Or do you have example when that is broken? > > Is get_signal_to_deliver() ever called at any time other than when the CPU > is about to switch back into user mode? No, I don't think so. There's a check in do_signal() that only allows it to call get_signal_to_deliver() in user mode. > If not then there shouldn't be any problem. The routines I was talking > about earlier hold the USB device locks while running in kernel mode, but > they release them before returning to user mode. Then everything is correct, I think. Greetings, Rafael -- You never change things by fighting the existing reality. R. Buckminster Fuller
