[Cake] issue with Cake and bpf filter

Jonathan Morton chromatix99 at gmail.com
Sun Aug 12 09:41:00 EDT 2018

> On 12 Aug, 2018, at 1:23 pm, Pete Heist <pete at heistp.net> wrote:
> One more thing to add to this, when working with another bpf filter which is relatively similar to this simple one (although has some more innocuous looking code like map lookups and read-only operations on the skb) sometimes the attached is suddenly and repeatedly sent to both syslog and kern.log until the disk fills up...

> Aug 12 09:57:25 ubuntu kernel: [ 2408.152975] WARNING: CPU: 3 PID: 2304 at /home/a/src/sch_cake/sch_cake.c:2094 cake_dequeue+0x791/0xc70 [sch_cake]

> 	WARN_ON(host_load > CAKE_QUEUES);

Yeah, something is going seriously wrong here.  It shouldn't be possible for that warning to trigger; if it is, then Cake's internal data structures are being corrupted somehow.

But Cake doesn't directly read tc_classid from an skb.  So what could it be influencing?

 - Jonathan Morton

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