Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752660AbcDRPQl (ORCPT ); Mon, 18 Apr 2016 11:16:41 -0400 Received: from prod-mx.aristanetworks.com ([162.210.130.12]:62589 "EHLO prod-mx.aristanetworks.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751660AbcDRPQk (ORCPT ); Mon, 18 Apr 2016 11:16:40 -0400 From: Francesco Ruggeri To: Cc: "David S. Miller" , "Eric W. Biederman" , Mahesh Bandewar , Francesco Ruggeri Subject: [PATCH net-next] macvlan: fix failure during registration Date: Mon, 18 Apr 2016 08:16:21 -0700 Message-Id: <1460992581-46855-1-git-send-email-fruggeri@arista.com> X-Mailer: git-send-email 1.8.1.4 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3805 Lines: 127 If a macvlan/macvtap creation fails in register_netdevice in call_netdevice_notifiers(NETDEV_REGISTER) then while cleaning things up in rollback_registered_many it invokes macvlan_uninit. This results in port->count being decremented twice (in macvlan_uninit and in macvlan_common_newlink). A similar problem may exist in the ipvlan driver. This patch adds priv_flags to struct macvlan_dev and a flag that macvlan_uninit can use to determine if it is invoked in the context of a failed newlink. In macvtap_device_event(NETDEV_UNREGISTER) it also avoids cleaning up /dev/tapNN in case creation of the char device had previously failed. Tested in 3.18. The failure can be reproduced by running the script below a few times. The script creates macvtap interfaces in different namespaces causing along the way sysfs_warn_dup failures in macvtap_device_event(NETDEV_REGISTER) because of conflicting ifindexes, and finally a panic or "unregister_netdevice: waiting for ddev to become free". for ((ns=1; ns<3; ns++)) do ip netns add ns${ns} ip netns exec ns${ns} ip link add dev ddev type dummy done for ((ns=1; ns<3; ns++)) do for ((mv=0; mv<2; mv++)) do ret=1 while [ ${ret} != 0 ] do ip netns exec ns${ns} ip link add link ddev name \ macvtap${ns}${mv} type macvtap ret=$? done & done done sleep 5 ls /dev/tap* for ((ns=1; ns<3; ns++)) do ip netns exec ns${ns} ip link del ddev & done sleep 2 ls /dev/tap* for ((ns=1; ns<3; ns++)) do ip netns del ns${ns} done Signed-off-by: Francesco Ruggeri --- drivers/net/macvlan.c | 11 ++++++++--- drivers/net/macvtap.c | 2 ++ include/linux/if_macvlan.h | 3 +++ 3 files changed, 13 insertions(+), 3 deletions(-) diff --git a/drivers/net/macvlan.c b/drivers/net/macvlan.c index 2bcf1f3..11065af 100644 --- a/drivers/net/macvlan.c +++ b/drivers/net/macvlan.c @@ -823,9 +823,12 @@ static void macvlan_uninit(struct net_device *dev) free_percpu(vlan->pcpu_stats); macvlan_flush_sources(port, vlan); - port->count -= 1; - if (!port->count) - macvlan_port_destroy(port->dev); + + if (!(vlan->priv_flags & MACVLAN_PRIV_FLAG_REGISTERING)) { + port->count -= 1; + if (!port->count) + macvlan_port_destroy(port->dev); + } } static struct rtnl_link_stats64 *macvlan_dev_get_stats64(struct net_device *dev, @@ -1313,7 +1316,9 @@ int macvlan_common_newlink(struct net *src_net, struct net_device *dev, } port->count += 1; + vlan->priv_flags |= MACVLAN_PRIV_FLAG_REGISTERING; err = register_netdevice(dev); + vlan->priv_flags &= ~MACVLAN_PRIV_FLAG_REGISTERING; if (err < 0) goto destroy_port; diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c index 95394ed..e770221 100644 --- a/drivers/net/macvtap.c +++ b/drivers/net/macvtap.c @@ -1303,6 +1303,8 @@ static int macvtap_device_event(struct notifier_block *unused, } break; case NETDEV_UNREGISTER: + if (vlan->minor == 0) + break; devt = MKDEV(MAJOR(macvtap_major), vlan->minor); device_destroy(macvtap_class, devt); macvtap_free_minor(vlan); diff --git a/include/linux/if_macvlan.h b/include/linux/if_macvlan.h index a4ccc31..7cf82d8 100644 --- a/include/linux/if_macvlan.h +++ b/include/linux/if_macvlan.h @@ -48,6 +48,7 @@ struct macvlan_dev { netdev_features_t set_features; enum macvlan_mode mode; u16 flags; + u16 priv_flags; /* This array tracks active taps. */ struct macvtap_queue __rcu *taps[MAX_MACVTAP_QUEUES]; /* This list tracks all taps (both enabled and disabled) */ @@ -63,6 +64,8 @@ struct macvlan_dev { unsigned int macaddr_count; }; +#define MACVLAN_PRIV_FLAG_REGISTERING 1 + static inline void macvlan_count_rx(const struct macvlan_dev *vlan, unsigned int len, bool success, bool multicast) -- 1.8.1.4