tree 28ab536723891f977119ac51d2b1dbc00416a2ae
parent 504ad98df3a6b027ce997ca8f620e949cafb151f
author Soren Brinkmann <soren.brinkmann@xilinx.com> 1399243382 -0700
committer David S. Miller <davem@davemloft.net> 1399324278 -0400

net: macb: Fix race between HW and driver

Under "heavy" RX load, the driver cannot handle the descriptors fast
enough. In detail, when a descriptor is consumed, its used flag is
cleared and once the RX budget is consumed all descriptors with a
cleared used flag are prepared to receive more data. Under load though,
the HW may constantly receive more data and use those descriptors with a
cleared used flag before they are actually prepared for next usage.

The head and tail pointers into the RX-ring should always be valid and
we can omit clearing and checking of the used flag.

Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
Signed-off-by: David S. Miller <davem@davemloft.net>