Vincent Bernat
2017-Sep-15 21:17 UTC
[Bridge] [PATCH net-next v1] bridge: also trigger RTM_NEWLINK when interface is released from bridge
? 15 septembre 2017 21:38 +0200, Vincent Bernat <vincent at bernat.im>?:> Currently, when an interface is released from a bridge, we get a > RTM_DELLINK event through netlink: > > Deleted 2: dummy0: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 master bridge0 state UNKNOWN > link/ether 6e:23:c2:54:3a:b3It should be noted this only happens when using the ioctl API. When using the netlink API, rtnetlink.c will send a RTM_NEWLINK because of the modification. -- When in doubt, tell the truth. -- Mark Twain
Vincent Bernat
2017-Sep-16 14:18 UTC
[Bridge] [PATCH net-next v2] bridge: also trigger RTM_NEWLINK when interface is released from bridge
Currently, when an interface is released from a bridge via
ioctl(), we get a RTM_DELLINK event through netlink:
Deleted 2: dummy0: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 master bridge0
state UNKNOWN
link/ether 6e:23:c2:54:3a:b3
Userspace has to interpret that as a removal from the bridge, not as a
complete removal of the interface. When an bridged interface is
completely removed, we get two events:
Deleted 2: dummy0: <BROADCAST,NOARP> mtu 1500 master bridge0 state DOWN
link/ether 6e:23:c2:54:3a:b3
Deleted 2: dummy0: <BROADCAST,NOARP> mtu 1500 qdisc noop state DOWN group
default
link/ether 6e:23:c2:54:3a:b3 brd ff:ff:ff:ff:ff:ff
In constrast, when an interface is released from a bond, we get a
RTM_NEWLINK with only the new characteristics (no master):
3: dummy1: <BROADCAST,NOARP,SLAVE,UP,LOWER_UP> mtu 1500 qdisc noqueue
master bond0 state UNKNOWN group default
link/ether ae:dc:7a:8c:9a:3c brd ff:ff:ff:ff:ff:ff
3: dummy1: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc noqueue state
UNKNOWN group default
link/ether ae:dc:7a:8c:9a:3c brd ff:ff:ff:ff:ff:ff
4: bond0: <BROADCAST,MULTICAST,MASTER,UP,LOWER_UP> mtu 1500 qdisc noqueue
state UP group default
link/ether ae:dc:7a:8c:9a:3c brd ff:ff:ff:ff:ff:ff
3: dummy1: <BROADCAST,NOARP> mtu 1500 qdisc noqueue state DOWN group
default
link/ether ae:dc:7a:8c:9a:3c brd ff:ff:ff:ff:ff:ff
3: dummy1: <BROADCAST,NOARP> mtu 1500 qdisc noqueue state DOWN group
default
link/ether ca:c8:7b:66:f8:25 brd ff:ff:ff:ff:ff:ff
4: bond0: <BROADCAST,MULTICAST,MASTER,UP,LOWER_UP> mtu 1500 qdisc noqueue
state UP group default
link/ether ae:dc:7a:8c:9a:3c brd ff:ff:ff:ff:ff:ff
Userland may be confused by the fact we say a link is deleted while
its characteristics are only modified. A first solution would have
been to turn the RTM_DELLINK event in del_nbp() into a RTM_NEWLINK
event. However, maybe some piece of userland is relying on this
RTM_DELLINK to detect when a bridged interface is released. Instead,
we also emit a RTM_NEWLINK event once the interface is
released (without master info).
Deleted 2: dummy0: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 master bridge0
state UNKNOWN
link/ether 8a:bb:e7:94:b1:f8
2: dummy0: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc noqueue state
UNKNOWN group default
link/ether 8a:bb:e7:94:b1:f8 brd ff:ff:ff:ff:ff:ff
This is done only when using ioctl(). When using Netlink, such an
event is already automatically emitted in do_setlink().
Signed-off-by: Vincent Bernat <vincent at bernat.im>
---
net/bridge/br_ioctl.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/net/bridge/br_ioctl.c b/net/bridge/br_ioctl.c
index 7970f8540cbb..3148cb3a8e82 100644
--- a/net/bridge/br_ioctl.c
+++ b/net/bridge/br_ioctl.c
@@ -99,8 +99,10 @@ static int add_del_if(struct net_bridge *br, int ifindex, int
isadd)
if (isadd)
ret = br_add_if(br, dev);
- else
+ else {
ret = br_del_if(br, dev);
+ rtmsg_ifinfo(RTM_NEWLINK, dev, IFF_MASTER, GFP_KERNEL);
+ }
return ret;
}
--
2.14.1
David Miller
2017-Sep-20 21:09 UTC
[Bridge] [PATCH net-next v2] bridge: also trigger RTM_NEWLINK when interface is released from bridge
From: Vincent Bernat <vincent at bernat.im> Date: Sat, 16 Sep 2017 16:18:33 +0200 David, I am CC:'ing you because you've done work in this area over the past year. I'm applying this patch, it's been sitting since the 16th and likes entirely correct to me. But if you have objections just let me know.> Currently, when an interface is released from a bridge via > ioctl(), we get a RTM_DELLINK event through netlink: > > Deleted 2: dummy0: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 master bridge0 state UNKNOWN > link/ether 6e:23:c2:54:3a:b3 > > Userspace has to interpret that as a removal from the bridge, not as a > complete removal of the interface. When an bridged interface is > completely removed, we get two events: > > Deleted 2: dummy0: <BROADCAST,NOARP> mtu 1500 master bridge0 state DOWN > link/ether 6e:23:c2:54:3a:b3 > Deleted 2: dummy0: <BROADCAST,NOARP> mtu 1500 qdisc noop state DOWN group default > link/ether 6e:23:c2:54:3a:b3 brd ff:ff:ff:ff:ff:ff > > In constrast, when an interface is released from a bond, we get a > RTM_NEWLINK with only the new characteristics (no master): > > 3: dummy1: <BROADCAST,NOARP,SLAVE,UP,LOWER_UP> mtu 1500 qdisc noqueue master bond0 state UNKNOWN group default > link/ether ae:dc:7a:8c:9a:3c brd ff:ff:ff:ff:ff:ff > 3: dummy1: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN group default > link/ether ae:dc:7a:8c:9a:3c brd ff:ff:ff:ff:ff:ff > 4: bond0: <BROADCAST,MULTICAST,MASTER,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default > link/ether ae:dc:7a:8c:9a:3c brd ff:ff:ff:ff:ff:ff > 3: dummy1: <BROADCAST,NOARP> mtu 1500 qdisc noqueue state DOWN group default > link/ether ae:dc:7a:8c:9a:3c brd ff:ff:ff:ff:ff:ff > 3: dummy1: <BROADCAST,NOARP> mtu 1500 qdisc noqueue state DOWN group default > link/ether ca:c8:7b:66:f8:25 brd ff:ff:ff:ff:ff:ff > 4: bond0: <BROADCAST,MULTICAST,MASTER,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default > link/ether ae:dc:7a:8c:9a:3c brd ff:ff:ff:ff:ff:ff > > Userland may be confused by the fact we say a link is deleted while > its characteristics are only modified. A first solution would have > been to turn the RTM_DELLINK event in del_nbp() into a RTM_NEWLINK > event. However, maybe some piece of userland is relying on this > RTM_DELLINK to detect when a bridged interface is released. Instead, > we also emit a RTM_NEWLINK event once the interface is > released (without master info). > > Deleted 2: dummy0: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 master bridge0 state UNKNOWN > link/ether 8a:bb:e7:94:b1:f8 > 2: dummy0: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN group default > link/ether 8a:bb:e7:94:b1:f8 brd ff:ff:ff:ff:ff:ff > > This is done only when using ioctl(). When using Netlink, such an > event is already automatically emitted in do_setlink(). > > Signed-off-by: Vincent Bernat <vincent at bernat.im>Applied, thank you.