Alex reported the following crash when using fq_codel
with htb:
crash> bt
PID: 630839 TASK: ffff8823c990d280 CPU: 14 COMMAND: "tc"
[... snip ...]
#8 [ffff8820ceec17a0] page_fault at ffffffff8160a8c2
[exception RIP: htb_qlen_notify+24]
RIP: ffffffffa0841718 RSP: ffff8820ceec1858 RFLAGS: 00010282
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff88241747b400
RDX: ffff88241747b408 RSI: 0000000000000000 RDI: ffff8811fb27d000
RBP: ffff8820ceec1868 R8: ffff88120cdeff24 R9: ffff88120cdeff30
R10: 0000000000000bd4 R11: ffffffffa0840919 R12: ffffffffa0843340
R13: 0000000000000000 R14: 0000000000000001 R15: ffff8808dae5c2e8
ORIG_RAX: ffffffffffffffff CS: 0010 SS: 0018
#9 [...] qdisc_tree_decrease_qlen at ffffffff81565375
#10 [...] fq_codel_dequeue at ffffffffa084e0a0 [sch_fq_codel]
#11 [...] fq_codel_reset at ffffffffa084e2f8 [sch_fq_codel]
#12 [...] qdisc_destroy at ffffffff81560d2d
#13 [...] htb_destroy_class at ffffffffa08408f8 [sch_htb]
#14 [...] htb_put at ffffffffa084095c [sch_htb]
#15 [...] tc_ctl_tclass at ffffffff815645a3
#16 [...] rtnetlink_rcv_msg at ffffffff81552cb0
[... snip ...]
As Jamal pointed out, there is actually no need to call dequeue
to purge the queued skb's in reset, data structures can be just
reset explicitly. Therefore, we reset everything except config's
and stats, so that we would have a fresh start after device flipping.
Fixes: 4b549a2ef4 ("fq_codel: Fair Queue Codel AQM")
Reported-by: Alex Gartrell <agartrell@fb.com>
Cc: Alex Gartrell <agartrell@fb.com>
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
[xiyou.wangcong@gmail.com: added codel_vars_init() and qdisc_qstats_backlog_dec()]
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
3d0e0af406