As some driver authors seem to reintroduce dev->last_rx use,
add a comment to strongly discourage this.
Since commit 6cf3f41e6c (bonding, net: Move last_rx update into bonding
recv logic), network drivers dont need to update last_rx themselves,
unless they use this field to implement a timeout.
Not updating last_rx helps not dirtying a cache line, improving
performance in SMP.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
4dc89133f4