On Wed, 27 May 2020 02:04:26 +0200
Davide Caratti <dcara...@redhat.com> wrote:
> this command hangs forever:
>
> # tc qdisc add dev eth0 root fq_pie flows 65536
>
> watchdog: BUG: soft lockup - CPU#1 stuck for 23s! [tc:1028]
> [...]
> CPU: 1 PID: 1028 Comm: tc Not tainted 5.7.0-rc6+ #167
> RIP: 0010:fq_pie_init+0x60e/0x8b7 [sch_fq_pie]
> Code: 4c 89 65 50 48 89 f8 48 c1 e8 03 42 80 3c 30 00 0f 85 2a 02 00 00 48
> 8d 7d 10 4c 89 65 58 48 89 f8 48 c1 e8 03 42 80 3c 30 00 <0f> 85 a7 01 00 00
> 48 8d 7d 18 48 c7 45 10 46 c3 23 00 48 89 f8 48
> RSP: 0018:ffff888138d67468 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
> RAX: 1ffff9200018d2b2 RBX: ffff888139c1c400 RCX: ffffffffffffffff
> RDX: 000000000000c5e8 RSI: ffffc900000e5000 RDI: ffffc90000c69590
> RBP: ffffc90000c69580 R08: fffffbfff79a9699 R09: fffffbfff79a9699
> R10: 0000000000000700 R11: fffffbfff79a9698 R12: ffffc90000c695d0
> R13: 0000000000000000 R14: dffffc0000000000 R15: 000000002347c5e8
> FS: 00007f01e1850e40(0000) GS:ffff88814c880000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 000000000067c340 CR3: 000000013864c000 CR4: 0000000000340ee0
> Call Trace:
> qdisc_create+0x3fd/0xeb0
> tc_modify_qdisc+0x3be/0x14a0
> rtnetlink_rcv_msg+0x5f3/0x920
> netlink_rcv_skb+0x121/0x350
> netlink_unicast+0x439/0x630
> netlink_sendmsg+0x714/0xbf0
> sock_sendmsg+0xe2/0x110
> ____sys_sendmsg+0x5b4/0x890
> ___sys_sendmsg+0xe9/0x160
> __sys_sendmsg+0xd3/0x170
> do_syscall_64+0x9a/0x370
> entry_SYSCALL_64_after_hwframe+0x44/0xa9
>
> we can't accept 65536 as a valid number for 'nflows', because the loop on
> 'idx' in fq_pie_init() will never end. The extack message is correct, but
> it doesn't say that 0 is not a valid number for 'flows': while at it, fix
> this also. Add a tdc selftest to check correct validation of 'flows'.
>
> CC: Ivan Vecera <ivec...@redhat.com>
> Fixes: ec97ecf1ebe4 ("net: sched: add Flow Queue PIE packet scheduler")
> Signed-off-by: Davide Caratti <dcara...@redhat.com>
> ---
> net/sched/sch_fq_pie.c | 4 ++--
> .../tc-testing/tc-tests/qdiscs/fq_pie.json | 21 +++++++++++++++++++
> 2 files changed, 23 insertions(+), 2 deletions(-)
> create mode 100644
> tools/testing/selftests/tc-testing/tc-tests/qdiscs/fq_pie.json
>
> diff --git a/net/sched/sch_fq_pie.c b/net/sched/sch_fq_pie.c
> index a9da8776bf5b..fb760cee824e 100644
> --- a/net/sched/sch_fq_pie.c
> +++ b/net/sched/sch_fq_pie.c
> @@ -297,9 +297,9 @@ static int fq_pie_change(struct Qdisc *sch, struct nlattr
> *opt,
> goto flow_error;
> }
> q->flows_cnt = nla_get_u32(tb[TCA_FQ_PIE_FLOWS]);
> - if (!q->flows_cnt || q->flows_cnt > 65536) {
> + if (!q->flows_cnt || q->flows_cnt >= 65536) {
> NL_SET_ERR_MSG_MOD(extack,
> - "Number of flows must be < 65536");
> + "Number of flows must range in
> [1..65535]");
> goto flow_error;
> }
> }
> diff --git a/tools/testing/selftests/tc-testing/tc-tests/qdiscs/fq_pie.json
> b/tools/testing/selftests/tc-testing/tc-tests/qdiscs/fq_pie.json
> new file mode 100644
> index 000000000000..1cda2e11b3ad
> --- /dev/null
> +++ b/tools/testing/selftests/tc-testing/tc-tests/qdiscs/fq_pie.json
> @@ -0,0 +1,21 @@
> +[
> + {
> + "id": "83be",
> + "name": "Create FQ-PIE with invalid number of flows",
> + "category": [
> + "qdisc",
> + "fq_pie"
> + ],
> + "setup": [
> + "$IP link add dev $DUMMY type dummy || /bin/true"
> + ],
> + "cmdUnderTest": "$TC qdisc add dev $DUMMY root fq_pie flows 65536",
> + "expExitCode": "2",
> + "verifyCmd": "$TC qdisc show dev $DUMMY",
> + "matchPattern": "qdisc",
> + "matchCount": "0",
> + "teardown": [
> + "$IP link del dev $DUMMY"
> + ]
> + }
> +]
Good catch, Davide.
Reviewed-by: Ivan Vecera <ivec...@redhat.com>
