From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: softirqs are invoked while bottom halves are masked Date: Tue, 12 Jul 2011 03:01:04 -0700 (PDT) Message-ID: <20110712.030104.585873452291819607.davem@davemloft.net> References: Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: eric.dumazet@gmail.com, linuxppc-dev@ozlabs.org, ronny.meeus@gmail.com, netdev@vger.kernel.org To: patrickdepinguin+linuxppc@gmail.com Return-path: Received: from shards.monkeyblade.net ([198.137.202.13]:58081 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751241Ab1GLKCX (ORCPT ); Tue, 12 Jul 2011 06:02:23 -0400 In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: From: Thomas De Schampheleire Date: Tue, 12 Jul 2011 11:23:28 +0200 > Note that the reason we are seeing this problem, may be because the > kernel we are using contains some patches from Freescale. > Specifically, in dev_queue_xmit(), support is added for hardware queue > handling, just before entering the rcu_read_lock_bh(): > > if (dev->features & NETIF_F_HW_QDISC) { > txq = dev_pick_tx(dev, skb); > return dev_hard_start_xmit(skb, dev, txq); > } > > /* Disable soft irqs for various locks below. Also > * stops preemption for RCU. > */ > rcu_read_lock_bh(); > > We just tried moving the escaping to dev_hard_start_xmit() after > taking the lock, but this gives a large number of other problems, e.g. This is definitely why you are seeing this behavior. You cannot invoke dev_hard_start_xmit() without softirqs being disabled. It breaks everything. This is what happens when you integrate networking patches which were not reviewed and vetted on netdev.