On 06/10/2023 05:37, Christian Theune wrote:
Hi,
(prefix, I was not aware of the regression reporting process and incorrectly reported this informally with the developers mentioned in the change)
I upgraded from 6.1.38 to 6.1.55 this morning and it broke my traffic shaping script, leaving me with a non-functional uplink on a remote router.
The script errors out like this:
Oct 06 05:49:22 wendy00 isp-setup-shaping-start[2053]: + ext=ispA
Oct 06 05:49:22 wendy00 isp-setup-shaping-start[2053]: + ext_ingress=ifb0
Oct 06 05:49:22 wendy00 isp-setup-shaping-start[2053]: + modprobe ifb
Oct 06 05:49:22 wendy00 isp-setup-shaping-start[2053]: + modprobe act_mirred
Oct 06 05:49:22 wendy00 isp-setup-shaping-start[2053]: + tc qdisc del dev ispA root
Oct 06 05:49:22 wendy00 isp-setup-shaping-start[2061]: Error: Cannot delete qdisc with handle of zero.
Oct 06 05:49:22 wendy00 isp-setup-shaping-start[2053]: + true
Oct 06 05:49:22 wendy00 isp-setup-shaping-start[2053]: + tc qdisc del dev ispA ingress
Oct 06 05:49:22 wendy00 isp-setup-shaping-start[2064]: Error: Cannot find specified qdisc on specified device.
Oct 06 05:49:22 wendy00 isp-setup-shaping-start[2053]: + true
Oct 06 05:49:22 wendy00 isp-setup-shaping-start[2053]: + tc qdisc del dev ifb0 root
Oct 06 05:49:22 wendy00 isp-setup-shaping-start[2066]: Error: Cannot delete qdisc with handle of zero.
Oct 06 05:49:22 wendy00 isp-setup-shaping-start[2053]: + true
Oct 06 05:49:22 wendy00 isp-setup-shaping-start[2053]: + tc qdisc del dev ifb0 ingress
Oct 06 05:49:22 wendy00 isp-setup-shaping-start[2067]: Error: Cannot find specified qdisc on specified device.
Oct 06 05:49:22 wendy00 isp-setup-shaping-start[2053]: + true
Oct 06 05:49:22 wendy00 isp-setup-shaping-start[2053]: + tc qdisc add dev ispA handle ffff: ingress
Oct 06 05:49:22 wendy00 isp-setup-shaping-start[2053]: + ifconfig ifb0 up
Oct 06 05:49:22 wendy00 isp-setup-shaping-start[2053]: + tc filter add dev ispA parent ffff: protocol all u32 match u32 0 0 action mirred egress redirect dev ifb0
Oct 06 05:49:22 wendy00 isp-setup-shaping-start[2053]: + tc qdisc add dev ifb0 root handle 1: hfsc default 1
Oct 06 05:49:22 wendy00 isp-setup-shaping-start[2053]: + tc class add dev ifb0 parent 1: classid 1:999 hfsc rt m2 2.5gbit
Oct 06 05:49:22 wendy00 isp-setup-shaping-start[2053]: + tc class add dev ifb0 parent 1:999 classid 1:1 hfsc sc rate 50mbit
Oct 06 05:49:22 wendy00 isp-setup-shaping-start[2077]: Error: Invalid parent - parent class must have FSC.
The error message is also a bit weird (but that’s likely due to iproute2 being weird) as the CLI interface for `tc` and the error message do not map well. (I think I would have to choose `hfsc sc` on the parent to enable the FSC option which isn’t mentioned anywhere in the hfsc manpage).
The breaking change was introduced in 6.1.53[1] and a multitude of other currently supported kernels:
Hi,
Your script is actually incorrect.
`man 7 tc-hfsc` goes in depth into why, but I just wanna highlight this
section:
SEPARATE LS / RT SCs
Another difference from the original HFSC paper is that RT and
LS SCs can be specified separately. Moreover, leaf classes are
allowed to have only either RT SC or LS SC. For interior
classes, only LS SCs make sense: any RT SC will be ignored.
The last part ("For interior classes...") was what the referenced patch
fixed. We were mistakenly allowing RTs into "interior classes" which the
implementation never accounted for and this was a source of crashes. I'm
surprised you were lucky enough to never crash the kernel ;)
-=
I believe the script could be updated to the following and still achieve
the same results:
tc class add dev ifb0 parent 1: classid 1:999 hfsc ls m2 2.5gbit
tc class add dev ifb0 parent 1:999 classid 1:1 hfsc rt rate 50mbit
