net: netem: fix backlog accounting for corrupted GSO frames
authorJakub Kicinski <jakub.kicinski@netronome.com>
Mon, 17 Jun 2019 18:11:10 +0000 (11:11 -0700)
committerDavid S. Miller <davem@davemloft.net>
Wed, 19 Jun 2019 01:30:38 +0000 (21:30 -0400)
commit177b8007463c4f36c9a2c7ce7aa9875a4cad9bd5
tree0aaf0efa0b002eed26d9500d00dc1f31697da5e9
parent9476274093a0e79b905f4cd6cf6d149f65e02c17
net: netem: fix backlog accounting for corrupted GSO frames

When GSO frame has to be corrupted netem uses skb_gso_segment()
to produce the list of frames, and re-enqueues the segments one
by one.  The backlog length has to be adjusted to account for
new frames.

The current calculation is incorrect, leading to wrong backlog
lengths in the parent qdisc (both bytes and packets), and
incorrect packet backlog count in netem itself.

Parent backlog goes negative, netem's packet backlog counts
all non-first segments twice (thus remaining non-zero even
after qdisc is emptied).

Move the variables used to count the adjustment into local
scope to make 100% sure they aren't used at any stage in
backports.

Fixes: 6071bd1aa13e ("netem: Segment GSO packets on enqueue")
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Dirk van der Merwe <dirk.vandermerwe@netronome.com>
Acked-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net/sched/sch_netem.c