From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ingo Molnar Subject: Re: [GIT]: Networking Date: Wed, 5 Aug 2009 09:14:11 +0200 Message-ID: <20090805071411.GA9217@elte.hu> References: <20090804.125742.32009006.davem@davemloft.net> <20090805070205.GA8741@elte.hu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: torvalds@linux-foundation.org, akpm@linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org To: David Miller , Peter Zijlstra , Jiri Pirko Return-path: Received: from mx2.mail.elte.hu ([157.181.151.9]:39623 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933520AbZHEHO2 (ORCPT ); Wed, 5 Aug 2009 03:14:28 -0400 Content-Disposition: inline In-Reply-To: <20090805070205.GA8741@elte.hu> Sender: netdev-owner@vger.kernel.org List-ID: * Ingo Molnar wrote: > FYI, -tip testing found that these bits trigger a missing lockdep > annotation warning: it's apparently using an zero-initialized spinlock. This is a side-effect of: dev_unicast_init(dev); in alloc_netdev_mq() making use of dev->addr_list_lock. Wouldnt the patch below be the right fix? The device has just been allocated freshly, it's not accessible anywhere yet so no locking is needed at all - in fact it's wrong to lock it here (the lock isnt initialized yet). This bug was apparently introduced via: | commit a6ac65db2329e7685299666f5f7b6093c7b0f3a0 | Author: Jiri Pirko | Date: Thu Jul 30 01:06:12 2009 +0000 | | net: restore the original spinlock to protect unicast list it needlessly added new locking and apparently nobody ran this patch with lockdep. Ingo Index: linux2/net/core/dev.c =================================================================== --- linux2.orig/net/core/dev.c +++ linux2/net/core/dev.c @@ -4007,9 +4007,7 @@ static void dev_unicast_flush(struct net static void dev_unicast_init(struct net_device *dev) { - netif_addr_lock_bh(dev); __hw_addr_init(&dev->uc); - netif_addr_unlock_bh(dev); }