1, 3 and 4 are just mechanical fixes to make code cleaner. 2 fixes the bug that netfront generates oversize skbs. The fix was suggested by Ben. My test shows that netfront doesn''t generate oversize skb after this fix. 4 tries to coalesce slots before copying. This version enlarges the grant copy buffer to avoid overflow. 6 loosens the punishment when netback sees oversize packet. Wei.