From patchwork Thu Jul 2 18:38:36 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ralf Baechle X-Patchwork-Id: 490779 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 714A11402A8 for ; Fri, 3 Jul 2015 04:38:55 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754343AbbGBSit (ORCPT ); Thu, 2 Jul 2015 14:38:49 -0400 Received: from eddie.linux-mips.org ([148.251.95.138]:47084 "EHLO cvs.linux-mips.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754319AbbGBSiq (ORCPT ); Thu, 2 Jul 2015 14:38:46 -0400 Received: from localhost.localdomain ([127.0.0.1]:41349 "EHLO linux-mips.org" rhost-flags-OK-OK-OK-FAIL) by eddie.linux-mips.org with ESMTP id S27012793AbbGBSin7YL1m (ORCPT + 1 other); Thu, 2 Jul 2015 20:38:43 +0200 Received: from scotty.linux-mips.net (localhost.localdomain [127.0.0.1]) by scotty.linux-mips.net (8.15.1/8.14.8) with ESMTP id t62Icf1R021546; Thu, 2 Jul 2015 20:38:41 +0200 Received: (from ralf@localhost) by scotty.linux-mips.net (8.15.1/8.15.1/Submit) id t62Icaqk021543; Thu, 2 Jul 2015 20:38:36 +0200 Date: Thu, 2 Jul 2015 20:38:36 +0200 From: Ralf Baechle To: linux-hams@vger.kernel.org, netdev@vger.kernel.org, "Eric W. Biederman" Cc: Steven Whitehouse , Richard Stearn , f6bvp Subject: Bpqether broken in 4.1 Message-ID: <20150702183836.GA20390@linux-mips.org> MIME-Version: 1.0 Content-Disposition: inline User-Agent: Mutt/1.5.23 (2014-03-12) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Eric's Commit 1d5da757da860a6916adbf68b09e868062b4b3b8 (ax25: Stop using magic neighbour cache operations.) breaks IP traffic over the AX.25 bpqether driver. Here's how to reproduce the issue if you don't have an AX.25 setup. The arp command is there to fudge things if you don't have a peer that would answer ARP requests. # modprobe bpqether # ifconfig bpq0 hw ax25 abcdef-7 172.20.4.1/24 # arp -H ax25 -s 172.20.4.2 uvwxyz-9 # ping 172.20.4.2 Result in one "Dead loop on virtual device bpq0, fix it urgently!" message per ping packet. With the following little debug patch I get the following backtrace: [ 33.149171] Dead loop on virtual device bpq0, fix it urgently! [ 33.149718] ------------[ cut here ]------------ [ 33.149754] WARNING: CPU: 0 PID: 0 at net/core/dev.c:3014 __dev_queue_xmit+0x3f6/0x530() [ 33.149769] Modules linked in: [ 33.149789] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.1.0-00010-g21c6d95-dirty #18 [ 33.149799] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.8.1-20150318_183358- 04/01/2014 [ 33.149810] 0000000000000000 de52945c8e778a65 ffff88007fc039a8 ffffffff816d2165 [ 33.149823] 0000000000000000 0000000000000000 ffff88007fc039e8 ffffffff810634aa [ 33.149833] ffff88007fc039c8 0000000000000000 ffff880078f90000 ffff880078f90000 [ 33.149844] Call Trace: [ 33.149885] [] dump_stack+0x45/0x57 [ 33.149927] [] warn_slowpath_common+0x8a/0xc0 [ 33.149939] [] warn_slowpath_null+0x1a/0x20 [ 33.149949] [] __dev_queue_xmit+0x3f6/0x530 [ 33.149967] [] ? ttwu_do_wakeup+0x1d/0xe0 [ 33.149978] [] dev_queue_xmit_sk+0x13/0x20 [ 33.149994] [] ax25_queue_xmit+0x61/0x70 [ 33.150005] [] ax25_ip_xmit+0xd6/0x2d0 [ 33.150022] [] ? wake_up_process+0x27/0x50 [ 33.150050] [] bpq_xmit+0x1d5/0x200 [ 33.150061] [] dev_hard_start_xmit+0x264/0x3e0 [ 33.150073] [] __dev_queue_xmit+0x4bd/0x530 [ 33.150083] [] dev_queue_xmit_sk+0x13/0x20 [ 33.150099] [] neigh_connected_output+0xc2/0x110 [ 33.150110] [] neigh_update+0x333/0x770 [ 33.150117] [] arp_process.isra.15+0x2f7/0x690 [ 33.150117] [] arp_rcv+0xe6/0x130 [ 33.150117] [] __netif_receive_skb_core+0x693/0x830 [ 33.150117] [] __netif_receive_skb+0x18/0x60 [ 33.150117] [] process_backlog+0xb2/0x150 [ 33.150117] [] net_rx_action+0x212/0x340 [ 33.150117] [] __do_softirq+0x10b/0x2d0 [ 33.150117] [] irq_exit+0x145/0x150 [ 33.150117] [] do_IRQ+0x58/0xf0 [ 33.150117] [] common_interrupt+0x6e/0x6e [ 33.150117] [] ? native_safe_halt+0x6/0x10 [ 33.150117] [] ? rcu_eqs_enter+0xa3/0xb0 [ 33.150117] [] default_idle+0x1e/0xc0 [ 33.150117] [] arch_cpu_idle+0xf/0x20 [ 33.150117] [] cpu_startup_entry+0x377/0x3f0 [ 33.150117] [] rest_init+0x7c/0x80 [ 33.150117] [] start_kernel+0x484/0x4a5 [ 33.150117] [] ? early_idt_handler_array+0x120/0x120 [ 33.150117] [] x86_64_start_reservations+0x2a/0x2c [ 33.150117] [] x86_64_start_kernel+0x145/0x168 [ 33.150117] ---[ end trace ff4df9d904cced48 ]--- Ralf --- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html diff --git a/net/core/dev.c b/net/core/dev.c index aa82f9a..5fef868 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -3011,6 +3011,7 @@ static int __dev_queue_xmit(struct sk_buff *skb, void *accel_priv) recursion_alert: net_crit_ratelimited("Dead loop on virtual device %s, fix it urgently!\n", dev->name); + WARN_ON(1); } }