em/ix/ixv/ixl/iavf: Implement ifdi_needs_restart iflib method

[erj]

Summary

Pursuant to rS360398, implement driver-specific versions of the ifdi_needs_restart
iflib device method.

Some (if not most?) Intel network cards don't need reinitializing when a VLAN
is added or removed from the device hardware, so these implement ifdi_needs_restart
in a way that tell iflib not to bring the interface up or down when a VLAN is
added or removed, regardless of whether the VLAN_HWFILTER interface capability
flag is set or not.

This could potentially solve several PRs relating to link flaps that occur when
VLANs are added/removed to devices.

Signed-off-by: Eric Joyner <[e-mail]>

Test Plan

Ideally, someone would test this patch out by adding/removing VLANs on the various
network devices that this patch affects. iavf(4) doesn't need testing since I've
already worked on that, but the others do (probably not ixl(4) though).

[erj]

• Add em_if_needs_restart to igb's iflib device method list

[lev]

It helps me on 13-CURRENT with em, igb and ix.

[olivier]

Tested on igb and excellent result!

Before applying this patch (datastamp log message from Cisco switch console):

[root@IBM3]~# ifconfig igb2.5 create vlan 5 vlandev igb2 inet 192.168.50.1/24

May  6 21:04:22: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet1/0/17, changed state to down
May  6 21:04:23: %LINK-3-UPDOWN: Interface GigabitEthernet1/0/17, changed state to down
May  6 21:04:25: %LINK-3-UPDOWN: Interface GigabitEthernet1/0/17, changed state to up
May  6 21:04:26: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet1/0/17, changed state to up

[root@IBM3]~# ifconfig igb2.6 create vlan 6 vlandev igb2 inet 192.168.60.1/24

May  6 21:05:08: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet1/0/17, changed state to down
May  6 21:05:09: %LINK-3-UPDOWN: Interface GigabitEthernet1/0/17, changed state to down
May  6 21:05:12: %LINK-3-UPDOWN: Interface GigabitEthernet1/0/17, changed state to up
May  6 21:05:13: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet1/0/17, changed state to up

[root@IBM3]~#  ifconfig igb2.5 destroy

May  6 21:08:21: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet1/0/17, changed state to down
May  6 21:08:22: %LINK-3-UPDOWN: Interface GigabitEthernet1/0/17, changed state to down
May  6 21:08:24: %LINK-3-UPDOWN: Interface GigabitEthernet1/0/17, changed state to up
May  6 21:08:25: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet1/0/17, changed state to up

And after applying, no more link flapping :-)

[root@IBM3]~# ifconfig igb2.5 create vlan 5 vlandev igb2 inet 192.168.50.1/24
[root@IBM3]~# ifconfig igb2.6 create vlan 6 vlandev igb2 inet 192.168.60.1/24
[root@IBM3]~# ifconfig igb2.5 destroy