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Message-ID: <febbbc75-2cf5-1cf9-8ed9-6a42ff295ab9@kernel.org> Date: Sun, 9 Apr 2023 20:08:01 -0600 From: David Ahern <dsahern@...nel.org> To: Vladimir Oltean <vladimir.oltean@....com>, netdev@...r.kernel.org Cc: Jakub Kicinski <kuba@...nel.org>, "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, Paolo Abeni <pabeni@...hat.com>, Ido Schimmel <idosch@...dia.com> Subject: Re: [RFC PATCH net] net: ipv4/ipv6 addrconf: call igmp{,6}_group_dropped() while dev is still up [ cc Ido in case such a change has implications to mlxsw ] On 4/6/23 5:30 PM, Vladimir Oltean wrote: > ipv4 devinet calls ip_mc_down(), and ipv6 calls addrconf_ifdown(), and > both of these eventually result in calls to dev_mc_del(), either through > igmp_group_dropped() or igmp6_group_dropped(). > > The problem is that dev_mc_del() does call __dev_set_rx_mode(), but this > will not propagate all the way to the ndo_set_rx_mode() of the device, > because of this check: > > /* dev_open will call this function so the list will stay sane. */ > if (!(dev->flags&IFF_UP)) > return; > > and the NETDEV_DOWN notifier is emitted while the interface is already > down. OTOH we have NETDEV_GOING_DOWN which is emitted a bit earlier - > see: > > dev_close_many() > -> __dev_close_many() > -> call_netdevice_notifiers(NETDEV_GOING_DOWN, dev); > -> dev->flags &= ~IFF_UP; > -> call_netdevice_notifiers(NETDEV_DOWN, dev); > > Normally this oversight is easy to miss, because the addresses aren't > lost, just not synced to the device until the next up event. > > DSA does some processing in its dsa_slave_set_rx_mode(), and assumes > that all addresses that were synced are also unsynced by the time the > device is unregistered. Due to that assumption not being satisfied, > the WARN_ON(!list_empty(&dp->mdbs)); from dsa_switch_release_ports() > triggers, and we leak memory corresponding to the multicast addresses > that were never synced. > > Minimal reproducer: > ip link set swp0 up > ip link set swp0 down > echo 0000:00:00.5 > /sys/bus/pci/drivers/mscc_felix/unbind > > The proposal is to respond to that slightly earlier notifier with the > IGMP address deletion, so that the ndo_set_rx_mode() of the device does > actually get called. I am not familiar with the details of these layers, > but it appeared to me that NETDEV_DOWN needed to be replaced everywhere > with NETDEV_GOING_DOWN, so I blindly did that and it worked. > > Fixes: 5e8a1e03aa4d ("net: dsa: install secondary unicast and multicast addresses as host FDB/MDB") > Signed-off-by: Vladimir Oltean <vladimir.oltean@....com> > --- > Obviously DSA is not the only affected driver, but the extent to which > other drivers are impacted is not obvious to me. At least in DSA, there > is a WARN_ON() and a memory leak, so this is why I chose that Fixes tag. > > net/ipv4/devinet.c | 7 ++++--- > net/ipv6/addrconf.c | 12 ++++++------ > 2 files changed, 10 insertions(+), 9 deletions(-) > > diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c > index 5deac0517ef7..95690d16d651 100644 > --- a/net/ipv4/devinet.c > +++ b/net/ipv4/devinet.c > @@ -392,7 +392,8 @@ static void __inet_del_ifa(struct in_device *in_dev, > > rtmsg_ifa(RTM_DELADDR, ifa, nlh, portid); > blocking_notifier_call_chain(&inetaddr_chain, > - NETDEV_DOWN, ifa); > + NETDEV_GOING_DOWN, > + ifa); > inet_free_ifa(ifa); > } else { > promote = ifa; > @@ -429,7 +430,7 @@ static void __inet_del_ifa(struct in_device *in_dev, > So that, this order is correct. > */ > rtmsg_ifa(RTM_DELADDR, ifa1, nlh, portid); > - blocking_notifier_call_chain(&inetaddr_chain, NETDEV_DOWN, ifa1); > + blocking_notifier_call_chain(&inetaddr_chain, NETDEV_GOING_DOWN, ifa1); > > if (promote) { > struct in_ifaddr *next_sec; > @@ -1588,7 +1589,7 @@ static int inetdev_event(struct notifier_block *this, unsigned long event, > /* Send gratuitous ARP to notify of link change */ > inetdev_send_gratuitous_arp(dev, in_dev); > break; > - case NETDEV_DOWN: > + case NETDEV_GOING_DOWN: > ip_mc_down(in_dev); > break; > case NETDEV_PRE_TYPE_CHANGE: > diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c > index 3797917237d0..9e484f829f1c 100644 > --- a/net/ipv6/addrconf.c > +++ b/net/ipv6/addrconf.c > @@ -1307,7 +1307,7 @@ static void ipv6_del_addr(struct inet6_ifaddr *ifp) > > ipv6_ifa_notify(RTM_DELADDR, ifp); > > - inet6addr_notifier_call_chain(NETDEV_DOWN, ifp); > + inet6addr_notifier_call_chain(NETDEV_GOING_DOWN, ifp); > > if (action != CLEANUP_PREFIX_RT_NOP) { > cleanup_prefix_route(ifp, expires, > @@ -3670,12 +3670,12 @@ static int addrconf_notify(struct notifier_block *this, unsigned long event, > } > break; > > - case NETDEV_DOWN: > + case NETDEV_GOING_DOWN: > case NETDEV_UNREGISTER: > /* > * Remove all addresses from this interface. > */ > - addrconf_ifdown(dev, event != NETDEV_DOWN); > + addrconf_ifdown(dev, event != NETDEV_GOING_DOWN); > break; > > case NETDEV_CHANGENAME: > @@ -3741,7 +3741,7 @@ static bool addr_is_local(const struct in6_addr *addr) > > static int addrconf_ifdown(struct net_device *dev, bool unregister) > { > - unsigned long event = unregister ? NETDEV_UNREGISTER : NETDEV_DOWN; > + unsigned long event = unregister ? NETDEV_UNREGISTER : NETDEV_GOING_DOWN; > struct net *net = dev_net(dev); > struct inet6_dev *idev; > struct inet6_ifaddr *ifa; > @@ -3877,7 +3877,7 @@ static int addrconf_ifdown(struct net_device *dev, bool unregister) > > if (state != INET6_IFADDR_STATE_DEAD) { > __ipv6_ifa_notify(RTM_DELADDR, ifa); > - inet6addr_notifier_call_chain(NETDEV_DOWN, ifa); > + inet6addr_notifier_call_chain(NETDEV_GOING_DOWN, ifa); > } else { > if (idev->cnf.forwarding) > addrconf_leave_anycast(ifa); > @@ -6252,7 +6252,7 @@ static void dev_disable_change(struct inet6_dev *idev) > > netdev_notifier_info_init(&info, idev->dev); > if (idev->cnf.disable_ipv6) > - addrconf_notify(NULL, NETDEV_DOWN, &info); > + addrconf_notify(NULL, NETDEV_GOING_DOWN, &info); > else > addrconf_notify(NULL, NETDEV_UP, &info); > }
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