netdev - Re: [PATCH net v3] rtnl/bond: don't send rtnl msg for unregistered iface

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Message-ID: <20150512171248.GD9559@gospo.home.greyhouse.net>
Date:	Tue, 12 May 2015 13:12:50 -0400
From:	Andy Gospodarek <gospo@...ulusnetworks.com>
To:	Jiri Pirko <jiri@...nulli.us>
Cc:	Nicolas Dichtel <nicolas.dichtel@...nd.com>, davem@...emloft.net,
	netdev@...r.kernel.org, j.vosburgh@...il.com, vfalico@...il.com
Subject: Re: [PATCH net v3] rtnl/bond: don't send rtnl msg for unregistered
 iface

On Tue, May 12, 2015 at 05:58:42PM +0200, Jiri Pirko wrote:
> Tue, May 12, 2015 at 05:17:45PM CEST, nicolas.dichtel@...nd.com wrote:
> >Before the patch, the command 'ip link add bond2 type bond mode 802.3ad'
> >causes the kernel to send a rtnl message for the bond2 interface, with an
> >ifindex 0.
> >
> >'ip monitor' shows:
> >0: bond2: <BROADCAST,MULTICAST,MASTER> mtu 1500 state DOWN group default
> >    link/ether 00:00:00:00:00:00 brd ff:ff:ff:ff:ff:ff
> >9: bond2@...E: <BROADCAST,MULTICAST,MASTER> mtu 1500 qdisc noop state DOWN group default
> >    link/ether ea:3e:1f:53:92:7b brd ff:ff:ff:ff:ff:ff
> >[snip]
> >
> >First, nobody seems to care about NETDEV_CHANGEINFODATA (commit
> >d4261e565000 says that it was put only to notify userspace). Hence, we can
> >call directly rtmsg_ifinfo().
> 
> Please leave this notifier here. Will be needed in very near future for
> LAG offloading purposes.

I agree with this.  It is extremely useful for a variety of reasons (not
just the offload case), so please to do not remove it.

> 
> 
> 
> >Secondly, prevent in rtmsg_ifinfo() to send notifications to userspace
> >about unregistered interfaces.
> 
> I'm not sure about this. Why caller of rtmsg_ifinfo don't take care of
> it? Seems more logical to me.
> 
> 
> >
> >Fixes: d4261e565000 ("bonding: create netlink event when bonding option is changed")
> >CC: Jiri Pirko <jiri@...nulli.us>
> >Reported-by: Julien Meunier <julien.meunier@...nd.com>
> >Signed-off-by: Nicolas Dichtel <nicolas.dichtel@...nd.com>
> >---
> >
> >v3: move reg_state check in rtmsg_ifinfo()
> >
> >v2: check dev->reg_state instead of ifindex
> >    call rtmsg_ifinfo() directly in __bond_opt_set()
> >
> >There is about 20 occurences of "dev->reg_state .= NETREG_REGISTERED".
> >I will send a patch on net-next to introduce an helper for this when net
> >will be merged with this patch in net-next.
> >
> > drivers/net/bonding/bond_options.c | 2 +-
> > include/linux/netdevice.h          | 3 +--
> > net/core/rtnetlink.c               | 3 +++
> > 3 files changed, 5 insertions(+), 3 deletions(-)
> >
> >diff --git a/drivers/net/bonding/bond_options.c b/drivers/net/bonding/bond_options.c
> >index 4df28943d222..a2b72cc0e3e8 100644
> >--- a/drivers/net/bonding/bond_options.c
> >+++ b/drivers/net/bonding/bond_options.c
> >@@ -625,7 +625,7 @@ out:
> > 	if (ret)
> > 		bond_opt_error_interpret(bond, opt, ret, val);
> > 	else
> >-		call_netdevice_notifiers(NETDEV_CHANGEINFODATA, bond->dev);
> >+		rtmsg_ifinfo(RTM_NEWLINK, bond->dev, 0, GFP_KERNEL);
> > 
> > 	return ret;
> > }
> >diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
> >index 1899c74a7127..c040d48925fd 100644
> >--- a/include/linux/netdevice.h
> >+++ b/include/linux/netdevice.h
> >@@ -2069,8 +2069,7 @@ struct pcpu_sw_netstats {
> > #define NETDEV_CHANGEUPPER	0x0015
> > #define NETDEV_RESEND_IGMP	0x0016
> > #define NETDEV_PRECHANGEMTU	0x0017 /* notify before mtu change happened */
> >-#define NETDEV_CHANGEINFODATA	0x0018
> >-#define NETDEV_BONDING_INFO	0x0019
> >+#define NETDEV_BONDING_INFO	0x0018
> > 
> > int register_netdevice_notifier(struct notifier_block *nb);
> > int unregister_netdevice_notifier(struct notifier_block *nb);
> >diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
> >index 837d30b5ffed..7b25f1ef3d75 100644
> >--- a/net/core/rtnetlink.c
> >+++ b/net/core/rtnetlink.c
> >@@ -2415,6 +2415,9 @@ void rtmsg_ifinfo(int type, struct net_device *dev, unsigned int change,
> > {
> > 	struct sk_buff *skb;
> > 
> >+	if (dev->reg_state != NETREG_REGISTERED)
> >+		return;
> >+
> > 	skb = rtmsg_ifinfo_build_skb(type, dev, change, flags);
> > 	if (skb)
> > 		rtmsg_ifinfo_send(skb, dev, flags);
> >-- 
> >2.2.2
> >
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