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: NVincent Bernat <vincent@bernat.im> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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