Re: [PATCH 2/2] net: sched: convert qdisc linked list to hashtable

On 08/12/2016 04:36 PM, Jiri Kosina wrote:

On Fri, 12 Aug 2016, Daniel Borkmann wrote:

quoted

quoted

I was thinking about something like the patch below (the reasong being
that ->dev would be NULL only in cases of singletonish qdiscs) ...
wouldn't that also fix the issue you're seeing? Have to think it
through a little bit more ..

Ahh, so this has the same effect as previously observed with the other fix.

Thanks a lot for confirming that this fixes the panic. I still have to
think a little bit more about this though.

quoted

Perhaps it's just a dumping issue, but to the below clsact, there shouldn't
be pfifo_fast instances appearing.

# tc qdisc show dev wlp2s0b1
qdisc mq 0: root
qdisc pfifo_fast 0: parent :4 bands 3 priomap  1 2 2 2 1 2 0 0 1 1 1 1 1 1 1 1
qdisc pfifo_fast 0: parent :3 bands 3 priomap  1 2 2 2 1 2 0 0 1 1 1 1 1 1 1 1
qdisc pfifo_fast 0: parent :2 bands 3 priomap  1 2 2 2 1 2 0 0 1 1 1 1 1 1 1 1
qdisc pfifo_fast 0: parent :1 bands 3 priomap  1 2 2 2 1 2 0 0 1 1 1 1 1 1 1 1
# tc qdisc add dev wlp2s0b1 clsact
# tc qdisc show dev wlp2s0b1
qdisc mq 0: root
qdisc pfifo_fast 0: parent :4 bands 3 priomap  1 2 2 2 1 2 0 0 1 1 1 1 1 1 1 1
qdisc pfifo_fast 0: parent :3 bands 3 priomap  1 2 2 2 1 2 0 0 1 1 1 1 1 1 1 1
qdisc pfifo_fast 0: parent :2 bands 3 priomap  1 2 2 2 1 2 0 0 1 1 1 1 1 1 1 1
qdisc pfifo_fast 0: parent :1 bands 3 priomap  1 2 2 2 1 2 0 0 1 1 1 1 1 1 1 1
qdisc clsact ffff: parent ffff:fff1
qdisc pfifo_fast 0: parent :4 bands 3 priomap  1 2 2 2 1 2 0 0 1 1 1 1 1 1 1 1
qdisc pfifo_fast 0: parent :3 bands 3 priomap  1 2 2 2 1 2 0 0 1 1 1 1 1 1 1 1
qdisc pfifo_fast 0: parent :2 bands 3 priomap  1 2 2 2 1 2 0 0 1 1 1 1 1 1 1 1
qdisc pfifo_fast 0: parent :1 bands 3 priomap  1 2 2 2 1 2 0 0 1 1 1 1 1 1 1 1

Hmm, no immediate idea where those are coming from, we'll have to figure
it out. The mq device used here has 4 queues, right?

Yes, the first tc qdisc show is after boot and how it should normally
look like, so 4 tx queues.

# ls /sys/class/net/wlp2s0b1/queues/
rx-0  tx-0  tx-1  tx-2  tx-3

When adding clsact, only the 'qdisc clsact' line should be extra. Given
the extra pfifo_fast ones look the same as above, I would suspect a htab
dumping issue, perhaps. I can debug a bit later tonight on this.