| Message ID | 20230608123224.3191731-1-renmingshuai@huawei.com (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [v2] net/sched: Set the flushing flags to false to prevent an infinite loop and add one test to tdc | expand |
| Context | Check | Description |
|---|---|---|
| netdev/tree_selection | success | Not a local patch |
On 08/06/2023 09:32, renmingshuai wrote: >> On 07/06/2023 01:19, renmingshuai wrote: >>>> On 06/06/2023 11:45, renmingshuai wrote: >>>>> When a new chain is added by using tc, one soft lockup alarm will >>>>> be >>>>> generated after delete the prio 0 filter of the chain. To >>>>> reproduce >>>>> the problem, perform the following steps: >>>>> (1) tc qdisc add dev eth0 root handle 1: htb default 1 >>>>> (2) tc chain add dev eth0 >>>>> (3) tc filter del dev eth0 chain 0 parent 1: prio 0 >>>>> (4) tc filter add dev eth0 chain 0 parent 1: >>>> >>>> This seems like it could be added to tdc or 3 and 4 must be run in >>>> parallel? >>> 3 and 4 do not need to be run inparallel. When a new chain is added >>> by the >>> way as step 1 and the step 3 is completed, this problem always >>> occurs >>> whenever step 4 is run. >> >> Got it, >> The test still hangs with the provided patch. >> >> + tc qdisc add dev lo root handle 1: htb default 1 >> + tc chain add dev lo >> + tc filter del dev lo chain 0 parent 1: prio 0 >> [ 68.790030][ T6704] [+] >> [ 68.790060][ T6704] chain refcnt 2 >> [ 68.790951][ T6704] [-] >> + tc filter add dev lo chain 0 parent 1: >> <hangs> >> >> Also please add this test to tdc, it should be straightforward. >> > Sorry for not testing before. I forgot that the chain->refcnt was > increased by 1 when tcf_chain_get() is called in tc_del_tfilter(). > The value of chain->refcnt is 2 after chain flush. The test > result is as follows: > [root@localhost ~]# tc qdisc add dev eth2 root handle 1: htb default 1 > [root@localhost ~]# tc chain add dev eth2 > [root@localhost ~]# tc filter del dev eth2 chain 0 parent 1: prio 0 > [root@localhost ~]# tc filter add dev eth2 chain 0 parent 1: > Error: Filter kind and protocol must be specified. > We have an error talking to the kernel > > And I have add this test to tdc: > [root@localhost tc-testing]# ./tdc.py -f tc-tests/filters/tests.json > ok 7 c2b4 - Adding a new fiter after deleting a filter in a chain does > not cause an infinite loop > > Fixes: 726d061286ce ("net: sched: prevent insertion of new classifiers during chain flush") > Signed-off-by: renmingshuai <renmingshuai@huawei.com> Please respin with the following applied: diff --git a/tools/testing/selftests/tc-testing/tc-tests/filters/tests.json b/tools/testing/selftests/tc-testing/tc-tests/filters/tests.json index c759c3db9a37..361235ad574b 100644 --- a/tools/testing/selftests/tc-testing/tc-tests/filters/tests.json +++ b/tools/testing/selftests/tc-testing/tc-tests/filters/tests.json @@ -125,25 +125,5 @@ "teardown": [ "$TC qdisc del dev $DEV2 ingress" ] - }, - { - "id": "c2b4", - "name": "Adding a new fiter after deleting a filter in a chain does not cause an infinite loop", - "category": [ - "filter", - "prio" - ], - "setup": [ - "$TC qdisc add dev $DEV1 root handle 1: htb default 1", - "$TC chain add dev $DEV1" - ], - "cmdUnderTest": "$TC filter del dev $DEV1 chain 0 parent 1: prio 0", - "expExitCode": "0", - "verifyCmd": "$TC filter add dev $DEV1 chain 0 parent 1:", - "matchPattern": "Error: Filter kind and protocol must be specified.", - "matchCount": "1", - "teardown": [ - "$TC qdisc del dev $DEV1 root handle 1: htb default 1" - ] } ] diff --git a/tools/testing/selftests/tc-testing/tc-tests/infra/filters.json b/tools/testing/selftests/tc-testing/tc-tests/infra/filters. json new file mode 100644 index 000000000000..55d6f209c388 --- /dev/null +++ b/tools/testing/selftests/tc-testing/tc-tests/infra/filters.json @@ -0,0 +1,24 @@ +[ + { + "id": "c2b4", + "name": "Adding a new filter after flushing empty chain doesnt cause an infinite loop", + "category": [ + "filter", + "chain" + ], + "setup": [ + "$IP link add dev $DUMMY type dummy || /bin/true", + "$TC qdisc add dev $DUMMY root handle 1: htb default 1", + "$TC chain add dev $DUMMY", + "$TC filter del dev $DUMMY chain 0 parent 1: prio 0" + ], + "cmdUnderTest": "$TC filter add dev $DUMMY chain 0 parent 1:", + "expExitCode": "2", + "verifyCmd": "$TC chain ls dev $DUMMY", + "matchPattern": "chain parent 1: chain 0", + "matchCount": "1", + "teardown": [ + "$TC qdisc del dev $DUMMY root handle 1: htb default 1" + ] + } +]
diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c index 2621550bfddc..3ea054e03fbf 100644 --- a/net/sched/cls_api.c +++ b/net/sched/cls_api.c @@ -2442,6 +2442,13 @@ static int tc_del_tfilter(struct sk_buff *skb, struct nlmsghdr *n, tfilter_notify_chain(net, skb, block, q, parent, n, chain, RTM_DELTFILTER, extack); tcf_chain_flush(chain, rtnl_held); + /* Set the flushing flags to false to prevent an infinite loop + * when a new filter is added. + */ + mutex_lock(&chain->filter_chain_lock); + if (chain->refcnt == 2) + chain->flushing = false; + mutex_unlock(&chain->filter_chain_lock); err = 0; goto errout; } diff --git a/tools/testing/selftests/tc-testing/tc-tests/filters/tests.json b/tools/testing/selftests/tc-testing/tc-tests/filters/tests.json index 361235ad574b..f165ca091109 100644 --- a/tools/testing/selftests/tc-testing/tc-tests/filters/tests.json +++ b/tools/testing/selftests/tc-testing/tc-tests/filters/tests.json @@ -125,5 +125,25 @@ "teardown": [ "$TC qdisc del dev $DEV2 ingress" ] + }, + { + "id": "c2b4", + "name": "Adding a new fiter after deleting a filter in a chain does not cause an infinite loop", + "category": [ + "filter", + "prio" + ], + "setup": [ + "$TC qdisc add dev $DEV1 root handle 1: htb default 1", + "$TC chain add dev $DEV1" + ], + "cmdUnderTest": "$TC filter del dev $DEV1 chain 0 parent 1: prio 0", + "expExitCode": "0", + "verifyCmd": "$TC filter add dev $DEV1 chain 0 parent 1:", + "matchPattern": "Error: Filter kind and protocol must be specified.", + "matchCount": "1", + "teardown": [ + "$TC qdisc del dev $DEV1 root handle 1: htb default 1" + ] } ]