Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754092AbYGWJDX (ORCPT ); Wed, 23 Jul 2008 05:03:23 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751415AbYGWJDL (ORCPT ); Wed, 23 Jul 2008 05:03:11 -0400 Received: from casper.infradead.org ([85.118.1.10]:37054 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751229AbYGWJDJ (ORCPT ); Wed, 23 Jul 2008 05:03:09 -0400 Subject: Re: Kernel WARNING: at net/core/dev.c:1330 __netif_schedule+0x2c/0x98() From: Peter Zijlstra To: Jarek Poplawski Cc: David Miller , Larry.Finger@lwfinger.net, kaber@trash.net, torvalds@linux-foundation.org, akpm@linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-wireless@vger.kernel.org, mingo@redhat.com In-Reply-To: <20080723085452.GB4561@ff.dom.local> References: <20080722.160409.216536011.davem@davemloft.net> <20080723062036.GA4561@ff.dom.local> <20080723.005921.113868915.davem@davemloft.net> <20080723085452.GB4561@ff.dom.local> Content-Type: text/plain Date: Wed, 23 Jul 2008 11:03:06 +0200 Message-Id: <1216803786.7257.146.camel@twins> Mime-Version: 1.0 X-Mailer: Evolution 2.22.3.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2149 Lines: 64 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 > > 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]; In that case you can stick the key in there and do: int e1000e_init_tx_queue(struct net_tx_queue *txq) { ... spin_lock_init(&txq->tx_lock); lockdep_set_class(&txq->tx_lock, &txq->tx_lock_key); ... } ( This is what the scheduler runqueues also do ) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/