ix0 (iflib) vlans @ head & 12-stable

[Oleg Bulyzhin]

While testing 12-stable i've found following:

current ixgbe driver is using iflib and has IFCAP_VLAN_HWFILTER
enabled by default.

/sys/net/iflib.c iflib_vlan_[un]register() functions have this code:

/* Re-init to load the changes */
if (if_getcapenable(ifp) & IFCAP_VLAN_HWFILTER)
iflib_if_init_locked(ctx);

Thus any vlan reconfiguration leads to link flap. This is not
how it was before iflib conversion.

I'm not sure about other vlanhwfilter aware hardware but
intel x520-da2 cards (82599 chip) does not require re-init
after hwfilter reconfig.

Should we extend iflib framework a bit?

[Lev Serebryakov]

Post by Oleg Bulyzhin
current ixgbe driver is using iflib and has IFCAP_VLAN_HWFILTER
enabled by default.
/* Re-init to load the changes */
if (if_getcapenable(ifp) & IFCAP_VLAN_HWFILTER)
iflib_if_init_locked(ctx);
Thus any vlan reconfiguration leads to link flap. This is not
how it was before iflib conversion.

On 12 each cpability reconfiguration for em/igb/ix leads to link flap,
where 11 doesn't need this flap for most of capabilities of these cards.

IMHO, it is regression.