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Date: Sun, 15 Jan 2017 10:14:06 -0500
From: Jamal Hadi Salim <jhs@...atatu.com>
To: davem@...emloft.net
Cc: netdev@...r.kernel.org, xiyou.wangcong@...il.com,
Jamal Hadi Salim <jhs@...atatu.com>
Subject: [PATCH net 1/1] net sched actions: fix refcnt when GETing of action after bind
From: Jamal Hadi Salim <jhs@...atatu.com>
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@...atatu.com>
---
net/sched/act_api.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/net/sched/act_api.c b/net/sched/act_api.c
index 2095c83..e10456ef6f 100644
--- a/net/sched/act_api.c
+++ b/net/sched/act_api.c
@@ -900,8 +900,6 @@ static int tca_action_flush(struct net *net, struct nlattr *nla,
goto err;
}
act->order = i;
- if (event == RTM_GETACTION)
- act->tcfa_refcnt++;
list_add_tail(&act->list, &actions);
}
@@ -914,7 +912,8 @@ static int tca_action_flush(struct net *net, struct nlattr *nla,
return ret;
}
err:
- tcf_action_destroy(&actions, 0);
+ if (event != RTM_GETACTION)
+ tcf_action_destroy(&actions, 0);
return ret;
}
--
1.9.1
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