net: sched: fix ordering of qlen adjustment

commit 5eb7de8cd58e73851cd37ff8d0666517d9926948 upstream.

Changes to sch->q.qlen around qdisc_tree_reduce_backlog() need to happen
_before_ a call to said function because otherwise it may fail to notify
parent qdiscs when the child is about to become empty.

BUG=b/385096052
TEST=presubmit
RELEASE_NOTE=Fixed KCTF-5eb7de8 in the Linux kernel.

cos-patch: security-high
Change-Id: I05eb0a4b6b43bb9e4c987fd37946959588bb66ea
Signed-off-by: Lion Ackermann <[email protected]>
Acked-by: Toke Høiland-Jørgensen <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
Cc: Artem Metla <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
Signed-off-by: Kernel CVE Triage Automation <[email protected]>
Reviewed-on: https://cos-review.googlesource.com/c/third_party/kernel/+/89381
Tested-by: Cusky Presubmit Bot <[email protected]>
Reviewed-by: Shuo Yang <[email protected]>
Reviewed-by: He Gao <[email protected]>
2 files changed