On Wed, Jul 23, 2008 at 11:03:06AM +0200, Peter Zijlstra wrote: > On Wed, 2008-07-23 at 08:54 +0000, Jarek Poplawski wrote: > > On Wed, Jul 23, 2008 at 12:59:21AM -0700, David Miller wrote: > > > From: Jarek Poplawski <jarkao2@xxxxxxxxx> > > > Date: Wed, 23 Jul 2008 06:20:36 +0000 > > > > > > > PS: if there is nothing new in lockdep the classical method would > > > > be to change this static array: > > > > > > > > static struct lock_class_key > > > > netdev_xmit_lock_key[ARRAY_SIZE(netdev_lock_type)]; > > > > > > > > to > > > > > > > > static struct lock_class_key > > > > netdev_xmit_lock_key[ARRAY_SIZE(netdev_lock_type)][MAX_NUM_TX_QUEUES]; > > > > > > > > and set lockdep classes per queue as well. (If we are sure we don't > > > > need lockdep subclasses anywhere this could be optimized by using > > > > one lock_class_key per 8 queues and spin_lock_nested()). > > > > > > Unfortunately MAX_NUM_TX_QUEUES is USHORT_MAX, so this isn't really > > > a feasible approach. > > > > Is it used by real devices already? Maybe for the beginning we could > > start with something less? > > > > > spin_lock_nested() isn't all that viable either, as the subclass > > > limit is something like 8. > > > > This method would need to do some additional counting: depending of > > a queue number each 8 subsequent queues share (are set to) the same > > class and their number mod 8 gives the subqueue number for > > spin_lock_nested(). > > > > I'll try to find if there is something new around this in lockdep. > > (lockdep people added to CC.) > > There isn't. > > Is there a static data structure that the driver needs to instantiate to > 'create' a queue? Something like: > > /* this imaginary e1000 hardware has 16 hardware queues */ > static struct net_tx_queue e1000e_tx_queues[16]; I guess, not. Then, IMHO, we could be practical and simply skip lockdep validation for "some" range of locks: e.g. to set the table for the first 256 queues only, and to do e.g. __raw_spin_lock() for bigger numbers. (If there are any bad locking patterns this should be enough for checking.) Jarek P. -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
