If bridge have no sub-interfaces, it's status may be still with 'RUNNING'

If bridge have no sub-interfaces, it's status may be still with 'RUNNING'

[yzhu1]

Hi, all

I made this test on ubuntu 14.04 with kernel 3,19-rc7:

1. brctl addbr br0

2. ifconfig br0 up

3. ifconfig br0 (br0's status is with 'RUNNING')

4. brctl addif br0 eth0

5. brctl delif br0 eth0

6. ifconfig br0 (br0's status is without 'RUNNING')

When there is no sub-interface, the flag "RUNNING" is missing after the 
last sub-interface is removed.

As such, should we keep "RUNNING" flag after the last sub-interface is 
removed?

Thanks a lot.
Zhu Yanjun

Re: If bridge have no sub-interfaces, it's status may be still with 'RUNNING'

[yzhu1]

Add the maintainer of bridge.

Any reply is appreciated.

Zhu Yanjun

On 02/13/2015 05:57 PM, yzhu1 wrote:
> Hi, all
>
> I made this test on ubuntu 14.04 with kernel 3,19-rc7:
>
> 1. brctl addbr br0
>
> 2. ifconfig br0 up
>
> 3. ifconfig br0 (br0's status is with 'RUNNING')
>
> 4. brctl addif br0 eth0
>
> 5. brctl delif br0 eth0
>
> 6. ifconfig br0 (br0's status is without 'RUNNING')
>
> When there is no sub-interface, the flag "RUNNING" is missing after 
> the last sub-interface is removed.
>
> As such, should we keep "RUNNING" flag after the last sub-interface is 
> removed?
>
> Thanks a lot.
> Zhu Yanjun
> -- 
> To unsubscribe from this list: send the line "unsubscribe netdev" in
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>

Re: If bridge have no sub-interfaces, it's status may be still with 'RUNNING'

[Stephen Hemminger]

On Fri, 13 Feb 2015 17:57:45 +0800
yzhu1 <Yanjun.Zhu@windriver.com> wrote:

> Hi, all
> 
> I made this test on ubuntu 14.04 with kernel 3,19-rc7:
> 
> 1. brctl addbr br0
> 
> 2. ifconfig br0 up
> 
> 3. ifconfig br0 (br0's status is with 'RUNNING')
> 
> 4. brctl addif br0 eth0
> 
> 5. brctl delif br0 eth0
> 
> 6. ifconfig br0 (br0's status is without 'RUNNING')
> 
> When there is no sub-interface, the flag "RUNNING" is missing after the 
> last sub-interface is removed.
> 
> As such, should we keep "RUNNING" flag after the last sub-interface is 
> removed?

This is intentional. If there are no active ports in bridge, then
we want to tell applications that packets will go nowhere.

RE: If bridge have no sub-interfaces, it's status may be still with 'RUNNING'

[Wu, Kuaikuai]

Hi Stephen,
  When we up a bridge without sub-interfaces,  it has "RUNNING" flag as below. Is it correct or not?

1. brctl addbr br0
2. ifconfig br0 up
3. ifconfig br0 
br0 Link encap:Ethernet HWaddr e6:6c:84:a6:fc:64 
          inet6 addr: fe80::e46c:84ff:fea6:fc64/64 Scope:Link 
          UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0 
          TX packets:2 errors:0 dropped:0 overruns:0 carrier:0 
          collisions:0 txqueuelen:0 
          RX bytes:0 (0.0 B) TX bytes:168 (168.0 B)

Best Regards
Kuaikuai Wu

-----Original Message-----
From: Stephen Hemminger [mailto:stephen@networkplumber.org] 
Sent: Saturday, February 14, 2015 2:31 AM
To: Zhu, Yanjun
Cc: netdev; Wu, Kuaikuai; Tao, Yue
Subject: Re: If bridge have no sub-interfaces, it's status may be still with 'RUNNING'

On Fri, 13 Feb 2015 17:57:45 +0800
yzhu1 <Yanjun.Zhu@windriver.com> wrote:

> Hi, all
> 
> I made this test on ubuntu 14.04 with kernel 3,19-rc7:
> 
> 1. brctl addbr br0
> 
> 2. ifconfig br0 up
> 
> 3. ifconfig br0 (br0's status is with 'RUNNING')
> 
> 4. brctl addif br0 eth0
> 
> 5. brctl delif br0 eth0
> 
> 6. ifconfig br0 (br0's status is without 'RUNNING')
> 
> When there is no sub-interface, the flag "RUNNING" is missing after 
> the last sub-interface is removed.
> 
> As such, should we keep "RUNNING" flag after the last sub-interface is 
> removed?

This is intentional. If there are no active ports in bridge, then we want to tell applications that packets will go nowhere.

Re: If bridge have no sub-interfaces, it's status may be still with 'RUNNING'

[yzhu1]

[-- Attachment #1: Type: text/plain, Size: 934 bytes --]

Hi, Stephen

Follow your advice, I made a new patch. This patch will turn off
carrier when a new bridge interface is created. Please comment on it.

Thanks a lot.
Zhu Yanjun
On 02/14/2015 02:30 AM, Stephen Hemminger wrote:
> On Fri, 13 Feb 2015 17:57:45 +0800
> yzhu1 <Yanjun.Zhu@windriver.com> wrote:
>
>> Hi, all
>>
>> I made this test on ubuntu 14.04 with kernel 3,19-rc7:
>>
>> 1. brctl addbr br0
>>
>> 2. ifconfig br0 up
>>
>> 3. ifconfig br0 (br0's status is with 'RUNNING')
>>
>> 4. brctl addif br0 eth0
>>
>> 5. brctl delif br0 eth0
>>
>> 6. ifconfig br0 (br0's status is without 'RUNNING')
>>
>> When there is no sub-interface, the flag "RUNNING" is missing after the
>> last sub-interface is removed.
>>
>> As such, should we keep "RUNNING" flag after the last sub-interface is
>> removed?
> This is intentional. If there are no active ports in bridge, then
> we want to tell applications that packets will go nowhere.
>
>


[-- Attachment #2: 0001-bridge-turn-off-carrier-when-the-bridge-is-created.patch --]
[-- Type: text/x-patch, Size: 998 bytes --]

>From e03af5263bcaeea15442601e2a9f65c6b582352b Mon Sep 17 00:00:00 2001
From: Zhu Yanjun <Yanjun.Zhu@windriver.com>
Date: Mon, 16 Feb 2015 12:45:36 +0800
Subject: [PATCH 1/1] bridge: turn off carrier when the bridge is created

When a bridge interface is created, there is no any sub interface
in it. In this case, the packets should not go to this bridge interface.
As such, carrier is turned off.

Suggested-by: Stephen Hemminger <stephen@networkplumber.org>
Signed-off-by: Zhu Yanjun <Yanjun.Zhu@windriver.com>
---
 net/bridge/br_device.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/net/bridge/br_device.c b/net/bridge/br_device.c
index ffd379d..2d60474 100644
--- a/net/bridge/br_device.c
+++ b/net/bridge/br_device.c
@@ -394,4 +394,9 @@ void br_dev_setup(struct net_device *dev)
 	br_netfilter_rtable_init(br);
 	br_stp_timer_init(br);
 	br_multicast_init(br);
+
+	/* Shutdown bridge to avoid packets */
+	if (netif_carrier_ok(dev)) {
+		netif_carrier_off(dev);
+	}
 }
-- 
1.9.1

Re: If bridge have no sub-interfaces, it's status may be still with 'RUNNING'

[David Ahern]

On 2/15/15 9:55 PM, yzhu1 wrote:
>>> 1. brctl addbr br0
>>>
>>> 2. ifconfig br0 up
>>>
>>> 3. ifconfig br0 (br0's status is with 'RUNNING')
>>>
>>> 4. brctl addif br0 eth0
>>>
>>> 5. brctl delif br0 eth0
>>>
>>> 6. ifconfig br0 (br0's status is without 'RUNNING')
>>>
>>> When there is no sub-interface, the flag "RUNNING" is missing after the
>>> last sub-interface is removed.

I do not see that behavior with Fedora 21 and 3.18.5-201.fc21.x86_64. 
ie., after interface is removed br0 is still in up state. Perhaps a 
regression with 3.19.

>>>
>>> As such, should we keep "RUNNING" flag after the last sub-interface is
>>> removed?
>> This is intentional. If there are no active ports in bridge, then
>> we want to tell applications that packets will go nowhere.

It changes current behavior with respect to tcpdump. Today I can launch 
tcpdump on a bridge interface before starting a VM. With this change I 
will not be able to do that.

David

Re: If bridge have no sub-interfaces, it's status may be still with 'RUNNING'

[Stephen Hemminger]

Originally bridge code would start with carrier off,
but there were users using bridge as a form of dummy device
and this broke them. Therefore it was decided (like 5 yrs ago),
that bridge should start with carrier on.

Re: If bridge have no sub-interfaces, it's status may be still with 'RUNNING'

[Stephen Hemminger]

On Mon, 16 Feb 2015 12:55:47 +0800
yzhu1 <Yanjun.Zhu@windriver.com> wrote:

> Hi, Stephen
> 
> Follow your advice, I made a new patch. This patch will turn off
> carrier when a new bridge interface is created. Please comment on it.
> 
> Thanks a lot.
> Zhu Yanjun

NAK.
We need to keep the current behavior to not break corner case users.

RE: If bridge have no sub-interfaces, it's status may be still with 'RUNNING'

[Zhu, Yanjun]

[-- Attachment #1: Type: text/plain, Size: 759 bytes --]

Hi, all

We should make it compatible. So I made a patch to turn on carrier on this bridge interface when the last sub interface is removed.

Hi, David

Please make tests with this latest patch. Thanks a lot.

Best Regards!
Zhu Yanjun
________________________________________
From: Stephen Hemminger [stephen@networkplumber.org]
Sent: Monday, February 16, 2015 8:51 AM
To: David Ahern
Cc: Zhu, Yanjun; netdev; Wu, Kuaikuai; Tao, Yue
Subject: Re: If bridge have no sub-interfaces, it's status may be still with 'RUNNING'

Originally bridge code would start with carrier off,
but there were users using bridge as a form of dummy device
and this broke them. Therefore it was decided (like 5 yrs ago),
that bridge should start with carrier on.

[-- Attachment #2: 0001-bridge-turn-on-carrier-after-removing-the-last-sub-i.patch --]
[-- Type: text/plain, Size: 1025 bytes --]

From 0d16f302f23c9f5101f849450abc073045a193de Mon Sep 17 00:00:00 2001
From: Zhu Yanjun <Yanjun.Zhu@windriver.com>
Date: Tue, 17 Feb 2015 23:59:08 +0800
Subject: [PATCH 1/1] bridge: turn on carrier after removing the last sub
 interface

When the last sub interface is removed from the bridge, the bridge
turn off the carrier. Maybe it is not compatible with firstly created
bridge without any sub interface. At that time, the carrier of this
bridge is turned on.

Signed-off-by: Zhu Yanjun <Yanjun.Zhu@windriver.com>
---
 net/bridge/br_if.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/net/bridge/br_if.c b/net/bridge/br_if.c
index ed307db..f391f8c 100644
--- a/net/bridge/br_if.c
+++ b/net/bridge/br_if.c
@@ -565,6 +565,12 @@ int br_del_if(struct net_bridge *br, struct net_device *dev)
 
 	netdev_update_features(br->dev);
 
+	/* No sub interface in bridge, turn on carrier */
+	if (list_empty(&br->port_list)) {
+		eth_hw_addr_random(br->dev);
+		netif_carrier_on(br->dev);
+	}
+
 	return 0;
 }
 
-- 
1.9.1

Re: If bridge have no sub-interfaces, it's status may be still with 'RUNNING'

[yzhu1]

Hi, Stephen && David

Any update?

Zhu Yanjun

On 02/18/2015 12:14 AM, Zhu, Yanjun wrote:
> Hi, all
>
> We should make it compatible. So I made a patch to turn on carrier on this bridge interface when the last sub interface is removed.
>
> Hi, David
>
> Please make tests with this latest patch. Thanks a lot.
>
> Best Regards!
> Zhu Yanjun
> ________________________________________
> From: Stephen Hemminger [stephen@networkplumber.org]
> Sent: Monday, February 16, 2015 8:51 AM
> To: David Ahern
> Cc: Zhu, Yanjun; netdev; Wu, Kuaikuai; Tao, Yue
> Subject: Re: If bridge have no sub-interfaces, it's status may be still with 'RUNNING'
>
> Originally bridge code would start with carrier off,
> but there were users using bridge as a form of dummy device
> and this broke them. Therefore it was decided (like 5 yrs ago),
> that bridge should start with carrier on.

Re: If bridge have no sub-interfaces, it's status may be still with 'RUNNING'

[David Ahern]

On 2/24/15 7:55 PM, yzhu1 wrote:
> Hi, Stephen && David
>
> Any update?

As I mentioned in my last response I see no problem with the existing 
behavior -- 3.18, 3.19 and 4.0-rc1. With all of them the bridge stays in 
the running state after all interfaces are removed.

David

Re: If bridge have no sub-interfaces, it's status may be still with 'RUNNING'

[yzhu1]

On 02/25/2015 12:23 PM, David Ahern wrote:
> On 2/24/15 7:55 PM, yzhu1 wrote:
>> Hi, Stephen && David
>>
>> Any update?
>
> As I mentioned in my last response I see no problem with the existing 
> behavior -- 3.18, 3.19 and 4.0-rc1. With all of them the bridge stays 
> in the running state after all interfaces are removed.
>
> David
>
>
>
Hi, David

I made tests on kernel 3.19-rc7.

1. brctl addbr br0

2. ifconfig br0 up

3. ifconfig br0 (br0's status is with 'RUNNING')

br0       Link encap:Ethernet  HWaddr 0a:70:0b:06:34:8f
           inet6 addr: fe80::870:bff:fe06:348f/64 Scope:Link
           UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
           RX packets:0 errors:0 dropped:0 overruns:0 frame:0
           TX packets:16 errors:0 dropped:0 overruns:0 carrier:0
           collisions:0 txqueuelen:0
           RX bytes:0 (0.0 B)  TX bytes:5054 (5.0 KB)

4. brctl addif br0 eth1

5. brctl delif br0 eth1

6. ifconfig br0 (br0's status is without 'RUNNING')

br0       Link encap:Ethernet  HWaddr 00:00:00:00:00:00
           inet6 addr: fe80::870:bff:fe06:348f/64 Scope:Link
           UP BROADCAST MULTICAST  MTU:1500  Metric:1
           RX packets:328 errors:0 dropped:5 overruns:0 frame:0
           TX packets:19 errors:0 dropped:0 overruns:0 carrier:0
           collisions:0 txqueuelen:0
           RX bytes:39997 (39.9 KB)  TX bytes:5760 (5.7 KB)

Please compare with the outputs of step 3 and step 6, we can find the 
difference.

uname:

Linux wind-virtual-machine 3.19.0-rc7 #2 SMP Wed Jan 28 18:36:44 CST 
2015 x86_64 x86_64 x86_64 GNU/Linux

So I think we should apply the latest patch to make consistent.

Any reply is appreciated.

Zhu Yanjun

Re: If bridge have no sub-interfaces, it's status may be still with 'RUNNING'

[yzhu1]

Hi, Stephen && David

Any update ?

Best Regards!
Zhu Yanjun
On 02/16/2015 12:55 PM, yzhu1 wrote:
> Hi, Stephen
>
> Follow your advice, I made a new patch. This patch will turn off
> carrier when a new bridge interface is created. Please comment on it.
>
> Thanks a lot.
> Zhu Yanjun
> On 02/14/2015 02:30 AM, Stephen Hemminger wrote:
>> On Fri, 13 Feb 2015 17:57:45 +0800
>> yzhu1 <Yanjun.Zhu@windriver.com> wrote:
>>
>>> Hi, all
>>>
>>> I made this test on ubuntu 14.04 with kernel 3,19-rc7:
>>>
>>> 1. brctl addbr br0
>>>
>>> 2. ifconfig br0 up
>>>
>>> 3. ifconfig br0 (br0's status is with 'RUNNING')
>>>
>>> 4. brctl addif br0 eth0
>>>
>>> 5. brctl delif br0 eth0
>>>
>>> 6. ifconfig br0 (br0's status is without 'RUNNING')
>>>
>>> When there is no sub-interface, the flag "RUNNING" is missing after the
>>> last sub-interface is removed.
>>>
>>> As such, should we keep "RUNNING" flag after the last sub-interface is
>>> removed?
>> This is intentional. If there are no active ports in bridge, then
>> we want to tell applications that packets will go nowhere.
>>
>>
>