On Sat, 8 Aug 2009, Jiri Kosina wrote: > Actually, I remember having discussed this with some of you guys some time > ago, and I thought that the conclusion was that > > a) disconnect() used to do lock_kernel() > b) nobody has actually done the hard work of checking all open() methods > for dependency on BKL Yes, that's true in general. But some individual cases have been done, and I wondered whether (or why not) usbhid was among them. > In hiddev we need BKL simply because we need a lock which usb_open() also > takes in the right order, so that we avoid race between usb_register_dev() > and open(). > > We can't use simple mutex to guard hiddev_table[], because usb_open() and > usb_register_dev() lock minor_rwsem, and we would end up with ABBA > deadlock. Tell me, why do you need hiddev_table at all? Can't you use usb_find_interface() to look up devices given their minor numbers? That's how other USB class drivers work. Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
