[PATCH net] bridge: a netlink notification should be sent whenever those attributes change

Now when we change the attributes of bridge or br_port by netlink,
a relevant netlink notification will be sent, but if we change them
by ioctl or sysfs, no notification will be sent.

we should ensure that whenever those attributes change internally or from
sysfs/ioctl, that a netlink notification is sent out to listeners.

Also, NetworkManager will use this in the future to listen for out-of-band
bridge master attribute updates and incorporate them into the runtime
configuration.

Signed-off-by: Xin Long <lucien.xin@gmail.com>
---
 net/bridge/br_ioctl.c    | 40 ++++++++++++++++++++++++----------------
 net/bridge/br_sysfs_br.c |  2 ++
 net/bridge/br_sysfs_if.c |  4 +++-
 3 files changed, 29 insertions(+), 17 deletions(-)

diff --git a/net/bridge/br_ioctl.c b/net/bridge/br_ioctl.c
index 263b4de..f8fc624 100644
--- a/net/bridge/br_ioctl.c
+++ b/net/bridge/br_ioctl.c

@@ -112,7 +112,9 @@ static int add_del_if(struct net_bridge *br, int ifindex, int isadd)
 static int old_dev_ioctl(struct net_device *dev, struct ifreq *rq, int cmd)
 {
 	struct net_bridge *br = netdev_priv(dev);
+	struct net_bridge_port *p = NULL;
 	unsigned long args[4];
+	int ret = -EOPNOTSUPP;
 
 	if (copy_from_user(args, rq->ifr_data, sizeof(args)))
 		return -EFAULT;

@@ -182,25 +184,29 @@ static int old_dev_ioctl(struct net_device *dev, struct ifreq *rq, int cmd)
 		if (!ns_capable(dev_net(dev)->user_ns, CAP_NET_ADMIN))
 			return -EPERM;
 
-		return br_set_forward_delay(br, args[1]);
+		ret = br_set_forward_delay(br, args[1]);
+		break;
 
 	case BRCTL_SET_BRIDGE_HELLO_TIME:
 		if (!ns_capable(dev_net(dev)->user_ns, CAP_NET_ADMIN))
 			return -EPERM;
 
-		return br_set_hello_time(br, args[1]);
+		ret = br_set_hello_time(br, args[1]);
+		break;
 
 	case BRCTL_SET_BRIDGE_MAX_AGE:
 		if (!ns_capable(dev_net(dev)->user_ns, CAP_NET_ADMIN))
 			return -EPERM;
 
-		return br_set_max_age(br, args[1]);
+		ret = br_set_max_age(br, args[1]);
+		break;
 
 	case BRCTL_SET_AGEING_TIME:
 		if (!ns_capable(dev_net(dev)->user_ns, CAP_NET_ADMIN))
 			return -EPERM;
 
-		return br_set_ageing_time(br, args[1]);
+		ret = br_set_ageing_time(br, args[1]);
+		break;
 
 	case BRCTL_GET_PORT_INFO:
 	{

@@ -240,20 +246,19 @@ static int old_dev_ioctl(struct net_device *dev, struct ifreq *rq, int cmd)
 			return -EPERM;
 
 		br_stp_set_enabled(br, args[1]);
-		return 0;
+		ret = 0;
+		break;
 
 	case BRCTL_SET_BRIDGE_PRIORITY:
 		if (!ns_capable(dev_net(dev)->user_ns, CAP_NET_ADMIN))
 			return -EPERM;
 
 		br_stp_set_bridge_priority(br, args[1]);
-		return 0;
+		ret = 0;
+		break;
 
 	case BRCTL_SET_PORT_PRIORITY:
 	{
-		struct net_bridge_port *p;
-		int ret;
-
 		if (!ns_capable(dev_net(dev)->user_ns, CAP_NET_ADMIN))
 			return -EPERM;
 

@@ -263,14 +268,11 @@ static int old_dev_ioctl(struct net_device *dev, struct ifreq *rq, int cmd)
 		else
 			ret = br_stp_set_port_priority(p, args[2]);
 		spin_unlock_bh(&br->lock);
-		return ret;
+		break;
 	}
 
 	case BRCTL_SET_PATH_COST:
 	{
-		struct net_bridge_port *p;
-		int ret;
-
 		if (!ns_capable(dev_net(dev)->user_ns, CAP_NET_ADMIN))
 			return -EPERM;
 

@@ -280,8 +282,7 @@ static int old_dev_ioctl(struct net_device *dev, struct ifreq *rq, int cmd)
 		else
 			ret = br_stp_set_path_cost(p, args[2]);
 		spin_unlock_bh(&br->lock);
-
-		return ret;
+		break;
 	}
 
 	case BRCTL_GET_FDB_ENTRIES:

@@ -289,7 +290,14 @@ static int old_dev_ioctl(struct net_device *dev, struct ifreq *rq, int cmd)
 				       args[2], args[3]);
 	}
 
-	return -EOPNOTSUPP;
+	if (!ret) {
+		if (p)
+			br_ifinfo_notify(RTM_NEWLINK, p);
+		else
+			netdev_state_change(br->dev);
+	}
+
+	return ret;
 }
 
 static int old_deviceless(struct net *net, void __user *uarg)

diff --git a/net/bridge/br_sysfs_br.c b/net/bridge/br_sysfs_br.c
index 6b80914..231e093 100644
--- a/net/bridge/br_sysfs_br.c
+++ b/net/bridge/br_sysfs_br.c

@@ -44,6 +44,8 @@ static ssize_t store_bridge_parm(struct device *d,
 		return -EINVAL;
 
 	err = (*set)(br, val);
+	if (!err)
+		netdev_state_change(br->dev);
 	return err ? err : len;
 }
 

diff --git a/net/bridge/br_sysfs_if.c b/net/bridge/br_sysfs_if.c
index efe415a..0ad8592 100644
--- a/net/bridge/br_sysfs_if.c
+++ b/net/bridge/br_sysfs_if.c

@@ -253,8 +253,10 @@ static ssize_t brport_store(struct kobject *kobj,
 			spin_lock_bh(&p->br->lock);
 			ret = brport_attr->store(p, val);
 			spin_unlock_bh(&p->br->lock);
-			if (ret == 0)
+			if (ret == 0) {
+				br_ifinfo_notify(RTM_NEWLINK, p);
 				ret = count;
+			}
 		}
 		rtnl_unlock();
 	}

-- 
2.1.0

On 03/03/2016 01:16 PM, Xin Long wrote:

Now when we change the attributes of bridge or br_port by netlink,
a relevant netlink notification will be sent, but if we change them
by ioctl or sysfs, no notification will be sent.

we should ensure that whenever those attributes change internally or from
sysfs/ioctl, that a netlink notification is sent out to listeners.

Also, NetworkManager will use this in the future to listen for out-of-band
bridge master attribute updates and incorporate them into the runtime
configuration.

Signed-off-by: Xin Long <lucien.xin@gmail.com>
---
 net/bridge/br_ioctl.c    | 40 ++++++++++++++++++++++++----------------
 net/bridge/br_sysfs_br.c |  2 ++
 net/bridge/br_sysfs_if.c |  4 +++-
 3 files changed, 29 insertions(+), 17 deletions(-)

[snip]

This is incorrect because you don't have rtnl here, bridge device sysfs
options take care of rtnl only on per-option basis and they obtain and 
release it themselves, so you won't have rtnl held when you call
netdev_state_change. While I agree that this is needed, a larger change
would be necessary for br_sysfs_br.c.
Off-topic: I've been looking into factoring out the bond option API and reusing
it here as it already has all of this handled, but I won't have time to finish
it before the next merge window, so if you fix the issue here I'm okay with
this as interim solution.

Cheers,
 Nik

On Thu, Mar 3, 2016 at 8:29 PM, Nikolay Aleksandrov
[off-list ref] wrote:

This is incorrect because you don't have rtnl here, bridge device sysfs
options take care of rtnl only on per-option basis and they obtain and
release it themselves, so you won't have rtnl held when you call
netdev_state_change. While I agree that this is needed, a larger change
would be necessary for br_sysfs_br.c.

Sorry, I can't follow you, cause I didn't see any held in dev_ioctl, like:
ipip6_tunnel_ioctl
    ipip6_tunnel_update
        netdev_state_change

why sysfs have to hold rtnl ?

Off-topic: I've been looking into factoring out the bond option API and reusing
it here as it already has all of this handled, but I won't have time to finish
it before the next merge window, so if you fix the issue here I'm okay with
this as interim solution.

Cheers,
 Nik

On 03/05/2016 03:44 PM, Xin Long wrote:

On Thu, Mar 3, 2016 at 8:29 PM, Nikolay Aleksandrov
[off-list ref] wrote:

quoted

This is incorrect because you don't have rtnl here, bridge device sysfs
options take care of rtnl only on per-option basis and they obtain and
release it themselves, so you won't have rtnl held when you call
netdev_state_change. While I agree that this is needed, a larger change
would be necessary for br_sysfs_br.c.

Sorry, I can't follow you, cause I didn't see any held in dev_ioctl, like:
ipip6_tunnel_ioctl
    ipip6_tunnel_update
        netdev_state_change

why sysfs have to hold rtnl ?

See the comment above dev_ifsioc:
/*
 *      Perform the SIOCxIFxxx calls, inside rtnl_lock()
 */
static int dev_ifsioc(struct net *net, struct ifreq *ifr, unsigned int cmd)
{
...
it is usually called like:
                       rtnl_lock();
                       ret = dev_ifsioc(net, &ifr, cmd);
                       rtnl_unlock();
And also you cannot be calling netdevice notifiers without RTNL. So in any
case you do need it here as well, in fact you'll surely hit the ASSERT_RTNL();
in call_netdevice_notifiers_info if you do so, thus I'm not sure how this
patch was actually tested.

quoted

Off-topic: I've been looking into factoring out the bond option API and reusing
it here as it already has all of this handled, but I won't have time to finish
it before the next merge window, so if you fix the issue here I'm okay with
this as interim solution.

Cheers,
 Nik

On Sun, Mar 6, 2016 at 3:43 AM, Nikolay Aleksandrov
[off-list ref] wrote:

On 03/05/2016 03:44 PM, Xin Long wrote:

See the comment above dev_ifsioc:
/*
 *      Perform the SIOCxIFxxx calls, inside rtnl_lock()
 */
static int dev_ifsioc(struct net *net, struct ifreq *ifr, unsigned int cmd)
{
...
it is usually called like:
                       rtnl_lock();
                       ret = dev_ifsioc(net, &ifr, cmd);
                       rtnl_unlock();
And also you cannot be calling netdevice notifiers without RTNL. So in any
case you do need it here as well, in fact you'll surely hit the ASSERT_RTNL();
in call_netdevice_notifiers_info if you do so, thus I'm not sure how this
patch was actually tested.

yes, I can see it now.
I will repost this patch with rtnl_lock in br_sysfs_*.
Thanks Nik.