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Date: Tue, 02 Dec 2014 08:08:56 -0800
From: Roopa Prabhu <roopa@...ulusnetworks.com>
To: Mahesh Bandewar <maheshb@...gle.com>
CC: netdev <netdev@...r.kernel.org>,
David Miller <davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>,
Toshiaki Makita <makita.toshiaki@....ntt.co.jp>
Subject: Re: [PATCH net-next] rtnetlink: delay RTM_DELLINK notification until
after ndo_uninit()
On 12/1/14, 9:54 PM, Mahesh Bandewar wrote:
> The commit 56bfa7ee7c ("unregister_netdevice : move RTM_DELLINK to
> until after ndo_uninit") tried to do this ealier but while doing so
> it created a problem. Unfortunately the delayed rtmsg_ifinfo() also
> delayed call to fill_info(). So this translated into asking driver
> to remove private state and then quert it's private state. This
> could have catastropic consequences.
>
> This change breaks the rtmsg_ifinfo() into two parts - one fills the
> skb by calling fill_info() prior to calling ndo_uninit() and the second
> part just sends the message using the skb filled earlier.
>
> It was brought to notice when last link is deleted from an ipvlan device
> when it has free-ed the port and the subsequent .fill_info() call is
> trying to get the info from the port.
>
> kernel: [ 255.139429] ------------[ cut here ]------------
> kernel: [ 255.139439] WARNING: CPU: 12 PID: 11173 at net/core/rtnetlink.c:2238 rtmsg_ifinfo+0x100/0x110()
> kernel: [ 255.139493] Modules linked in: ipvlan bonding w1_therm ds2482 wire cdc_acm ehci_pci ehci_hcd i2c_dev i2c_i801 i2c_core msr cpuid bnx2x ptp pps_core mdio libcrc32c
> kernel: [ 255.139513] CPU: 12 PID: 11173 Comm: ip Not tainted 3.18.0-smp-DEV #167
> kernel: [ 255.139514] Hardware name: Intel RML,PCH/Ibis_QC_18, BIOS 1.0.10 05/15/2012
> kernel: [ 255.139515] 0000000000000009 ffff880851b6b828 ffffffff815d87f4 00000000000000e0
> kernel: [ 255.139516] 0000000000000000 ffff880851b6b868 ffffffff8109c29c 0000000000000000
> kernel: [ 255.139518] 00000000ffffffa6 00000000000000d0 ffffffff81aaf580 0000000000000011
> kernel: [ 255.139520] Call Trace:
> kernel: [ 255.139527] [<ffffffff815d87f4>] dump_stack+0x46/0x58
> kernel: [ 255.139531] [<ffffffff8109c29c>] warn_slowpath_common+0x8c/0xc0
> kernel: [ 255.139540] [<ffffffff8109c2ea>] warn_slowpath_null+0x1a/0x20
> kernel: [ 255.139544] [<ffffffff8150d570>] rtmsg_ifinfo+0x100/0x110
> kernel: [ 255.139547] [<ffffffff814f78b5>] rollback_registered_many+0x1d5/0x2d0
> kernel: [ 255.139549] [<ffffffff814f79cf>] unregister_netdevice_many+0x1f/0xb0
> kernel: [ 255.139551] [<ffffffff8150acab>] rtnl_dellink+0xbb/0x110
> kernel: [ 255.139553] [<ffffffff8150da90>] rtnetlink_rcv_msg+0xa0/0x240
> kernel: [ 255.139557] [<ffffffff81329283>] ? rhashtable_lookup_compare+0x43/0x80
> kernel: [ 255.139558] [<ffffffff8150d9f0>] ? __rtnl_unlock+0x20/0x20
> kernel: [ 255.139562] [<ffffffff8152cb11>] netlink_rcv_skb+0xb1/0xc0
> kernel: [ 255.139563] [<ffffffff8150a495>] rtnetlink_rcv+0x25/0x40
> kernel: [ 255.139565] [<ffffffff8152c398>] netlink_unicast+0x178/0x230
> kernel: [ 255.139567] [<ffffffff8152c75f>] netlink_sendmsg+0x30f/0x420
> kernel: [ 255.139571] [<ffffffff814e0b0c>] sock_sendmsg+0x9c/0xd0
> kernel: [ 255.139575] [<ffffffff811d1d7f>] ? rw_copy_check_uvector+0x6f/0x130
> kernel: [ 255.139577] [<ffffffff814e11c9>] ? copy_msghdr_from_user+0x139/0x1b0
> kernel: [ 255.139578] [<ffffffff814e1774>] ___sys_sendmsg+0x304/0x310
> kernel: [ 255.139581] [<ffffffff81198723>] ? handle_mm_fault+0xca3/0xde0
> kernel: [ 255.139585] [<ffffffff811ebc4c>] ? destroy_inode+0x3c/0x70
> kernel: [ 255.139589] [<ffffffff8108e6ec>] ? __do_page_fault+0x20c/0x500
> kernel: [ 255.139597] [<ffffffff811e8336>] ? dput+0xb6/0x190
> kernel: [ 255.139606] [<ffffffff811f05f6>] ? mntput+0x26/0x40
> kernel: [ 255.139611] [<ffffffff811d2b94>] ? __fput+0x174/0x1e0
> kernel: [ 255.139613] [<ffffffff814e2129>] __sys_sendmsg+0x49/0x90
> kernel: [ 255.139615] [<ffffffff814e2182>] SyS_sendmsg+0x12/0x20
> kernel: [ 255.139617] [<ffffffff815df092>] system_call_fastpath+0x12/0x17
> kernel: [ 255.139619] ---[ end trace 5e6703e87d984f6b ]---
interestingly I have never seen this. We use this heavily with most
other logical devices.
Which tells me most logical devices do have checks in their fill_info.
The patch idea is good. My only concern is stale information
in the DELLINK notification. Because, ndo_uninit() does do a lot of
cleanup, sending
newlink's for some of these cleanup changes. And now with your patch the
dellink notification
skb probably contains information that has been already deleted by
ndo_uninit ?
>
> Signed-off-by: Mahesh Bandewar <maheshb@...gle.com>
> Report-by: Toshiaki Makita <makita.toshiaki@....ntt.co.jp>
> Cc: Eric Dumazet <edumazet@...gle.com>
> Cc: Roopa Prabhu <roopa@...ulusnetworks.com>
> Cc: David S. Miller <davem@...emloft.net>
> ---
> drivers/net/bonding/bond_main.c | 4 ++--
> include/linux/rtnetlink.h | 6 +++++-
> include/net/bonding.h | 8 ++++----
> net/core/dev.c | 26 ++++++++++++++++----------
> net/core/rtnetlink.c | 20 ++++++++++++++++----
> 5 files changed, 43 insertions(+), 21 deletions(-)
>
> diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
> index 184c434ae305..06206a1439a4 100644
> --- a/drivers/net/bonding/bond_main.c
> +++ b/drivers/net/bonding/bond_main.c
> @@ -1135,7 +1135,7 @@ static int bond_master_upper_dev_link(struct net_device *bond_dev,
> if (err)
> return err;
> slave_dev->flags |= IFF_SLAVE;
> - rtmsg_ifinfo(RTM_NEWLINK, slave_dev, IFF_SLAVE, GFP_KERNEL);
> + rtmsg_ifinfo(RTM_NEWLINK, slave_dev, IFF_SLAVE, GFP_KERNEL, false);
> return 0;
> }
>
> @@ -1144,7 +1144,7 @@ static void bond_upper_dev_unlink(struct net_device *bond_dev,
> {
> netdev_upper_dev_unlink(slave_dev, bond_dev);
> slave_dev->flags &= ~IFF_SLAVE;
> - rtmsg_ifinfo(RTM_NEWLINK, slave_dev, IFF_SLAVE, GFP_KERNEL);
> + rtmsg_ifinfo(RTM_NEWLINK, slave_dev, IFF_SLAVE, GFP_KERNEL, false);
> }
>
> static struct slave *bond_alloc_slave(struct bonding *bond)
> diff --git a/include/linux/rtnetlink.h b/include/linux/rtnetlink.h
> index 6cacbce1a06c..545dd0b8c83d 100644
> --- a/include/linux/rtnetlink.h
> +++ b/include/linux/rtnetlink.h
> @@ -16,7 +16,11 @@ extern int rtnetlink_put_metrics(struct sk_buff *skb, u32 *metrics);
> extern int rtnl_put_cacheinfo(struct sk_buff *skb, struct dst_entry *dst,
> u32 id, long expires, u32 error);
>
> -void rtmsg_ifinfo(int type, struct net_device *dev, unsigned change, gfp_t flags);
> +struct sk_buff *rtmsg_ifinfo(int type, struct net_device *dev, unsigned change,
> + gfp_t flags, bool fill_only);
> +void rtmsg_ifinfo_send(struct sk_buff *skb, struct net_device *dev,
> + gfp_t flags);
> +
>
> /* RTNL is used as a global lock for all changes to network configuration */
> extern void rtnl_lock(void);
> diff --git a/include/net/bonding.h b/include/net/bonding.h
> index 983a94b86b95..ea09f6c5af51 100644
> --- a/include/net/bonding.h
> +++ b/include/net/bonding.h
> @@ -315,7 +315,7 @@ static inline void bond_set_active_slave(struct slave *slave)
> {
> if (slave->backup) {
> slave->backup = 0;
> - rtmsg_ifinfo(RTM_NEWLINK, slave->dev, 0, GFP_ATOMIC);
> + rtmsg_ifinfo(RTM_NEWLINK, slave->dev, 0, GFP_ATOMIC, false);
> }
> }
>
> @@ -323,7 +323,7 @@ static inline void bond_set_backup_slave(struct slave *slave)
> {
> if (!slave->backup) {
> slave->backup = 1;
> - rtmsg_ifinfo(RTM_NEWLINK, slave->dev, 0, GFP_ATOMIC);
> + rtmsg_ifinfo(RTM_NEWLINK, slave->dev, 0, GFP_ATOMIC, false);
> }
> }
>
> @@ -335,7 +335,7 @@ static inline void bond_set_slave_state(struct slave *slave,
>
> slave->backup = slave_state;
> if (notify) {
> - rtmsg_ifinfo(RTM_NEWLINK, slave->dev, 0, GFP_ATOMIC);
> + rtmsg_ifinfo(RTM_NEWLINK, slave->dev, 0, GFP_ATOMIC, false);
> slave->should_notify = 0;
> } else {
> if (slave->should_notify)
> @@ -365,7 +365,7 @@ static inline void bond_slave_state_notify(struct bonding *bond)
>
> bond_for_each_slave(bond, tmp, iter) {
> if (tmp->should_notify) {
> - rtmsg_ifinfo(RTM_NEWLINK, tmp->dev, 0, GFP_ATOMIC);
> + rtmsg_ifinfo(RTM_NEWLINK, tmp->dev, 0, GFP_ATOMIC, false);
> tmp->should_notify = 0;
> }
> }
> diff --git a/net/core/dev.c b/net/core/dev.c
> index ac4836241a96..29bc78d5e6cb 100644
> --- a/net/core/dev.c
> +++ b/net/core/dev.c
> @@ -1230,7 +1230,7 @@ void netdev_state_change(struct net_device *dev)
> change_info.flags_changed = 0;
> call_netdevice_notifiers_info(NETDEV_CHANGE, dev,
> &change_info.info);
> - rtmsg_ifinfo(RTM_NEWLINK, dev, 0, GFP_KERNEL);
> + rtmsg_ifinfo(RTM_NEWLINK, dev, 0, GFP_KERNEL, false);
> }
> }
> EXPORT_SYMBOL(netdev_state_change);
> @@ -1319,7 +1319,7 @@ int dev_open(struct net_device *dev)
> if (ret < 0)
> return ret;
>
> - rtmsg_ifinfo(RTM_NEWLINK, dev, IFF_UP|IFF_RUNNING, GFP_KERNEL);
> + rtmsg_ifinfo(RTM_NEWLINK, dev, IFF_UP|IFF_RUNNING, GFP_KERNEL, false);
> call_netdevice_notifiers(NETDEV_UP, dev);
>
> return ret;
> @@ -1396,7 +1396,8 @@ static int dev_close_many(struct list_head *head)
> __dev_close_many(head);
>
> list_for_each_entry_safe(dev, tmp, head, close_list) {
> - rtmsg_ifinfo(RTM_NEWLINK, dev, IFF_UP|IFF_RUNNING, GFP_KERNEL);
> + rtmsg_ifinfo(RTM_NEWLINK, dev, IFF_UP|IFF_RUNNING,
> + GFP_KERNEL, false);
> call_netdevice_notifiers(NETDEV_DOWN, dev);
> list_del_init(&dev->close_list);
> }
> @@ -5683,7 +5684,7 @@ void __dev_notify_flags(struct net_device *dev, unsigned int old_flags,
> unsigned int changes = dev->flags ^ old_flags;
>
> if (gchanges)
> - rtmsg_ifinfo(RTM_NEWLINK, dev, gchanges, GFP_ATOMIC);
> + rtmsg_ifinfo(RTM_NEWLINK, dev, gchanges, GFP_ATOMIC, false);
>
> if (changes & IFF_UP) {
> if (dev->flags & IFF_UP)
> @@ -5925,6 +5926,8 @@ static void rollback_registered_many(struct list_head *head)
> synchronize_net();
>
> list_for_each_entry(dev, head, unreg_list) {
> + struct sk_buff *skb = NULL;
> +
> /* Shutdown queueing discipline. */
> dev_shutdown(dev);
>
> @@ -5934,6 +5937,10 @@ static void rollback_registered_many(struct list_head *head)
> */
> call_netdevice_notifiers(NETDEV_UNREGISTER, dev);
>
> + if (!dev->rtnl_link_ops ||
> + dev->rtnl_link_state == RTNL_LINK_INITIALIZED)
> + skb = rtmsg_ifinfo(RTM_DELLINK, dev, ~0U, GFP_KERNEL, true);
> +
> /*
> * Flush the unicast and multicast chains
> */
> @@ -5943,9 +5950,8 @@ static void rollback_registered_many(struct list_head *head)
> if (dev->netdev_ops->ndo_uninit)
> dev->netdev_ops->ndo_uninit(dev);
>
> - if (!dev->rtnl_link_ops ||
> - dev->rtnl_link_state == RTNL_LINK_INITIALIZED)
> - rtmsg_ifinfo(RTM_DELLINK, dev, ~0U, GFP_KERNEL);
> + if (skb)
> + rtmsg_ifinfo_send(skb, dev, GFP_KERNEL);
>
> /* Notifier chain MUST detach us all upper devices. */
> WARN_ON(netdev_has_any_upper_dev(dev));
> @@ -6334,7 +6340,7 @@ int register_netdevice(struct net_device *dev)
> */
> if (!dev->rtnl_link_ops ||
> dev->rtnl_link_state == RTNL_LINK_INITIALIZED)
> - rtmsg_ifinfo(RTM_NEWLINK, dev, ~0U, GFP_KERNEL);
> + rtmsg_ifinfo(RTM_NEWLINK, dev, ~0U, GFP_KERNEL, false);
>
> out:
> return ret;
> @@ -6959,7 +6965,7 @@ int dev_change_net_namespace(struct net_device *dev, struct net *net, const char
> call_netdevice_notifiers(NETDEV_UNREGISTER, dev);
> rcu_barrier();
> call_netdevice_notifiers(NETDEV_UNREGISTER_FINAL, dev);
> - rtmsg_ifinfo(RTM_DELLINK, dev, ~0U, GFP_KERNEL);
> + rtmsg_ifinfo(RTM_DELLINK, dev, ~0U, GFP_KERNEL, false);
>
> /*
> * Flush the unicast and multicast chains
> @@ -7000,7 +7006,7 @@ int dev_change_net_namespace(struct net_device *dev, struct net *net, const char
> * Prevent userspace races by waiting until the network
> * device is fully setup before sending notifications.
> */
> - rtmsg_ifinfo(RTM_NEWLINK, dev, ~0U, GFP_KERNEL);
> + rtmsg_ifinfo(RTM_NEWLINK, dev, ~0U, GFP_KERNEL, false);
>
> synchronize_net();
> err = 0;
> diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
> index b9b7dfaf202b..1035d8cdbc08 100644
> --- a/net/core/rtnetlink.c
> +++ b/net/core/rtnetlink.c
> @@ -2220,8 +2220,16 @@ static int rtnl_dump_all(struct sk_buff *skb, struct netlink_callback *cb)
> return skb->len;
> }
>
> -void rtmsg_ifinfo(int type, struct net_device *dev, unsigned int change,
> - gfp_t flags)
> +void rtmsg_ifinfo_send(struct sk_buff *skb, struct net_device *dev, gfp_t flags)
> +{
> + struct net *net = dev_net(dev);
> +
> + rtnl_notify(skb, net, 0, RTNLGRP_LINK, NULL, flags);
> +}
> +EXPORT_SYMBOL(rtmsg_ifinfo_send);
> +
> +struct sk_buff *rtmsg_ifinfo(int type, struct net_device *dev,
> + unsigned int change, gfp_t flags, bool fill_only)
> {
> struct net *net = dev_net(dev);
> struct sk_buff *skb;
> @@ -2239,11 +2247,15 @@ void rtmsg_ifinfo(int type, struct net_device *dev, unsigned int change,
> kfree_skb(skb);
> goto errout;
> }
> + if (fill_only)
> + return skb;
> +
> rtnl_notify(skb, net, 0, RTNLGRP_LINK, NULL, flags);
> - return;
> + return NULL;
> errout:
> if (err < 0)
> rtnl_set_sk_err(net, RTNLGRP_LINK, err);
> + return NULL;
> }
> EXPORT_SYMBOL(rtmsg_ifinfo);
>
> @@ -3011,7 +3023,7 @@ static int rtnetlink_event(struct notifier_block *this, unsigned long event, voi
> case NETDEV_JOIN:
> break;
> default:
> - rtmsg_ifinfo(RTM_NEWLINK, dev, 0, GFP_KERNEL);
> + rtmsg_ifinfo(RTM_NEWLINK, dev, 0, GFP_KERNEL, false);
> break;
> }
> return NOTIFY_DONE;
--
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