[Cake] [PATCH 3/4] sch_api: Allow reducing queue backlog by a negative value

[Eric Dumazet]

On 01/07/2019 11:47 AM, Toke Høiland-Jørgensen wrote:
> From: Toke Høiland-Jørgensen <toke at redhat.com>
> 
> With GSO splitting in sch_cake, we can decrease as well as increase the
> qlen. To make it possible to signal this up the qdisc tree, change
> qdisc_tree_reduce_backlog() to accept signed integer values as the number
> of packets and bytes to reduce the backlog by.


Not sure why this patch is needed, given we use u32 integers
for q.qlen & qstats.backlog

0xFFFFFFFF for n is really -1 once folded...

sch->q.qlen -= n;
sch->qstats.backlog -= len;