Current filer rule optimization is broken in several ways:
 (1) Can perform reads/writes beyond end of allocated tables.
     (gianfar_ethtool.c:1326).

(2) It breaks badly for rules with more than 2 specifiers
     (e.g. matching ip, port, tos).

Example:
# ethtool -N eth2 flow-type udp4 dst-ip 10.0.0.1 dst-port 1 tos 1 action 1
Added rule with ID 254
# ethtool -N eth2 flow-type udp4 dst-ip 10.0.0.2 dst-port 2 tos 2 action 9
Added rule with ID 253
# ethtool -N eth2 flow-type udp4 dst-ip 10.0.0.3 dst-port 3 tos 3 action 17
Added rule with ID 252
# ./filer_decode /sys/kernel/debug/gfar1/filer_raw
00: MASK == 00000210 AND         Q:00           ctrl:00000080 prop:00000210
01: FPR  == 00000210 AND CLE     Q:00           ctrl:00000281 prop:00000210
02: MASK == ffffffff AND         Q:00           ctrl:00000080 prop:ffffffff
03: DPT  == 00000003 AND         Q:00           ctrl:0000008e prop:00000003
04: TOS  == 00000003 AND         Q:00           ctrl:0000008a prop:00000003
05: DIA  == 0a000003 AND         Q:11           ctrl:0000448c prop:0a000003
06: DPT  == 00000002 AND         Q:00           ctrl:0000008e prop:00000002
07: TOS  == 00000002 AND         Q:00           ctrl:0000008a prop:00000002
08: DIA  == 0a000002 AND         Q:09           ctrl:0000248c prop:0a000002
09: DIA  == 0a000001 AND         Q:00           ctrl:0000008c prop:0a000001
0a: DPT  == 00000001 AND         Q:00           ctrl:0000008e prop:00000001
0b: TOS  == 00000001     CLE     Q:01           ctrl:0000060a prop:00000001
ff: MASK >= 00000000             Q:00           ctrl:00000020 prop:00000000

(Entire cluster gets AND-ed together).

 (3) We observed that the masking rules it generates do not
     play well with clustering on P2020.  Only first rule
     of the cluster would ever fire.  Given that optimizer
     relies heavily on masking this is very hard to fix.

Example:
# ethtool -N eth2 flow-type udp4 dst-ip 10.0.0.1 dst-port 1  action 1
Added rule with ID 254
# ethtool -N eth2 flow-type udp4 dst-ip 10.0.0.2 dst-port 2  action 9
Added rule with ID 253
# ethtool -N eth2 flow-type udp4 dst-ip 10.0.0.3 dst-port 3  action 17
Added rule with ID 252
# ./filer_decode /sys/kernel/debug/gfar1/filer_raw
00: MASK == 00000210 AND         Q:00           ctrl:00000080 prop:00000210
01: FPR  == 00000210 AND CLE     Q:00           ctrl:00000281 prop:00000210
02: MASK == ffffffff AND         Q:00           ctrl:00000080 prop:ffffffff
03: DPT  == 00000003 AND         Q:00           ctrl:0000008e prop:00000003
04: DIA  == 0a000003             Q:11           ctrl:0000440c prop:0a000003
05: DPT  == 00000002 AND         Q:00           ctrl:0000008e prop:00000002
06: DIA  == 0a000002             Q:09           ctrl:0000240c prop:0a000002
07: DIA  == 0a000001 AND         Q:00           ctrl:0000008c prop:0a000001
08: DPT  == 00000001     CLE     Q:01           ctrl:0000060e prop:00000001
ff: MASK >= 00000000             Q:00           ctrl:00000020 prop:00000000

Which looks correct according to the spec but only the first
(eth id 252)/last added rule for 10.0.0.3 will ever trigger.
As if filer did not treat the AND CLE as cluster start but
also kept AND-ing the rules.  We found no errata covering this.

The fact that nobody noticed (2) or (3) makes me think
that this feature is not very widely used and we should just
remove it.
Reported-by: Aleksander Dutkowski <adutkowski@gmail.com>
Signed-off-by: Jakub Kicinski <kubakici@wp.pl>
Acked-by: Claudiu Manoil <claudiu.manoil@freescale.com>
Signed-off-by: David S. Miller <davem@davemloft.net>