enic: preserve V2 VF carrier across netdev reopen

A V2 VF receives carrier state only from PF MBOX notifications.
enic_stop() forces carrier off, but enic_open() does not request a fresh
notification or restore the previous one.  An ordinary down/up cycle
therefore leaves the VF in NO-CARRIER and unable to pass traffic until the
PF repeats the link-state command, even when the physical link remained
up.

Cache each valid PF link-state notification.  Serialize updates with the V2
VF datapath running state.  Keep carrier off while the netdev is stopped.
Restore the cached state after an ordinary open.  Before either internal
reset reopens the datapath, invalidate the cache.  Carrier then remains off
until re-registration receives a fresh PF link-state notification.

Fixes: 72b65c94058e ("enic: add MBOX VF handlers for capability, register and link state")
Signed-off-by: Satish Kharat <satishkh@cisco.com>
Link: https://patch.msgid.link/20260830-b4-enic-v2-mbox-fixes-net-v1-1-23adf9bfd426@cisco.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

0 files changed, 0 insertions, 0 deletions