Re: iproute2: Behavioural Bug?

On Mon, Aug 24, 2015 at 02:00:29PM +0530, Akshat Kakkar wrote:

When I am trying to delete a single tc filter (i.e. specifying its
handle), it is deleting all the
filters with the same priority/preference. i.e. it is ignoring the
handle specified.

But, When I am doing similar activity in hashtable 800: it is deleting only the
specified filter, i.e. it is behaving as expected.

I am unable to comprehend the reason for this difference in behaviour.

Infact, in kernel 2.6.32 all is working as expected. However, in
kernel 3.1 and 4.1 it is having the behaviour as mentioned above.

For example, following set of commands  create a hashtable 15: and add
2 filters to it.

tc filter add dev eth0 parent 1:0 prio 5 handle 15: protocol ip u32 divisor 256
tc filter add dev eth0 protocol ip parent 1: prio 5 handle 15:2:2 u32
ht 15:2: match ip src 10.0.0.2 flowid 1:10
tc filter add dev eth0 protocol ip parent 1: prio 5 handle 15:2:3 u32
ht 15:2: match ip src 10.0.0.3 flowid 1:10

Now following command DELETES ALL THE FILTERS, though it should only
delete FILTER 15:2:3 !
tc filter del dev eth0 protocol ip parent 1: prio 5 handle 15:2:3 u32

O/p of tc filter show eth0 is this case is blank. As all filters are deleted.


However, similar commands when executed for hashtable 800: is deleting
only the specified filter
tc filter add dev eth0 protocol ip parent 1: prio 5 handle 800:0:2 u32
ht 800:0: match ip src 10.0.0.2 flowid 1:10
tc filter add dev eth0 protocol ip parent 1: prio 5 handle 800:0:3 u32
ht 800:0: match ip src 10.0.0.3 flowid 1:10

tc filter del dev eth0 protocol ip parent 1: prio 5 handle 800:0:2 u32

Above mentioned command only deletes single filter.
O/p of tc filter show eth0 is 2nd case is

filter parent 1: protocol ip pref 5 u32
filter parent 1: protocol ip pref 5 u32 fh 800: ht divisor 1
filter parent 1: protocol ip pref 5 u32 fh 800::3 order 3 key ht 800
bkt 0 flowid 1:10
  match 0a000003/ffffffff at 12
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Hi,

Thats what I got using this script where I copied your commands:

----------------------------------
#!/bin/bash

DEV=dummy0

ip link del $DEV 2> /dev/null

ip link add dev $DEV type dummy

tc qdisc add dev $DEV root handle 1: htb

tc filter add dev $DEV parent 1:0 prio 5 handle 15: protocol ip u32 divisor 256
tc filter add dev $DEV protocol ip parent 1: prio 5 handle 15:2:2 u32 ht 15:2: match ip src 10.0.0.2 flowid 1:10
tc filter add dev $DEV protocol ip parent 1: prio 5 handle 15:2:3 u32 ht 15:2: match ip src 10.0.0.3 flowid 1:10

tc filter del dev $DEV protocol ip parent 1: prio 5 handle 15:2:3 u32

tc filter show dev $DEV
# ---------------------------------

Result is:

filter parent 1: protocol ip pref 5 u32 
filter parent 1: protocol ip pref 5 u32 fh 15: ht divisor 256 
filter parent 1: protocol ip pref 5 u32 fh 15:2:2 order 2 key ht 15 bkt 2 flowid 1:10 
  match 0a000002/ffffffff at 12
filter parent 1: protocol ip pref 5 u32 fh 800: ht divisor 1 

Some additional info:

# tc -V
tc utility, iproute2-ss150413

# uname -a
Linux angus-think 4.0.4-2-ARCH #1 SMP PREEMPT Fri May 22 03:05:23 UTC 2015 x86_64 GNU/Linux

Regards,
Vadim Kochan