Commits
Jamal Hadi Salim committed 0faa9cb5b38
net sched actions: fix refcnt when GETing of action after bind
Demonstrating the issue:
.. add a drop action
$sudo $TC actions add action drop index 10
.. retrieve it
$ sudo $TC -s actions get action gact index 10
action order 1: gact action drop
random type none pass val 0
index 10 ref 2 bind 0 installed 29 sec used 29 sec
Action statistics:
Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0)
backlog 0b 0p requeues 0
... bug 1 above: reference is two.
Reference is actually 1 but we forget to subtract 1.
... do a GET again and we see the same issue
try a few times and nothing changes
~$ sudo $TC -s actions get action gact index 10
action order 1: gact action drop
random type none pass val 0
index 10 ref 2 bind 0 installed 31 sec used 31 sec
Action statistics:
Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0)
backlog 0b 0p requeues 0
... lets try to bind the action to a filter..
$ sudo $TC qdisc add dev lo ingress
$ sudo $TC filter add dev lo parent ffff: protocol ip prio 1 \
u32 match ip dst 127.0.0.1/32 flowid 1:1 action gact index 10
... and now a few GETs:
$ sudo $TC -s actions get action gact index 10
action order 1: gact action drop
random type none pass val 0
index 10 ref 3 bind 1 installed 204 sec used 204 sec
Action statistics:
Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0)
backlog 0b 0p requeues 0
$ sudo $TC -s actions get action gact index 10
action order 1: gact action drop
random type none pass val 0
index 10 ref 4 bind 1 installed 206 sec used 206 sec
Action statistics:
Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0)
backlog 0b 0p requeues 0
$ sudo $TC -s actions get action gact index 10
action order 1: gact action drop
random type none pass val 0
index 10 ref 5 bind 1 installed 235 sec used 235 sec
Action statistics:
Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0)
backlog 0b 0p requeues 0
.... as can be observed the reference count keeps going up.
After the fix
$ sudo $TC actions add action drop index 10
$ sudo $TC -s actions get action gact index 10
action order 1: gact action drop
random type none pass val 0
index 10 ref 1 bind 0 installed 4 sec used 4 sec
Action statistics:
Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0)
backlog 0b 0p requeues 0
$ sudo $TC -s actions get action gact index 10
action order 1: gact action drop
random type none pass val 0
index 10 ref 1 bind 0 installed 6 sec used 6 sec
Action statistics:
Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0)
backlog 0b 0p requeues 0
$ sudo $TC qdisc add dev lo ingress
$ sudo $TC filter add dev lo parent ffff: protocol ip prio 1 \
u32 match ip dst 127.0.0.1/32 flowid 1:1 action gact index 10
$ sudo $TC -s actions get action gact index 10
action order 1: gact action drop
random type none pass val 0
index 10 ref 2 bind 1 installed 32 sec used 32 sec
Action statistics:
Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0)
backlog 0b 0p requeues 0
$ sudo $TC -s actions get action gact index 10
action order 1: gact action drop
random type none pass val 0
index 10 ref 2 bind 1 installed 33 sec used 33 sec
Action statistics:
Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0)
backlog 0b 0p requeues 0
Fixes: aecc5cefc389 ("net sched actions: fix GETing actions")
Signed-off-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>