This bug report has Keywords: Regression or TestBlocker.
Since no regressions or test blockers are allowed between releases, it is also being identified as a blocker for this release. Please resolve ASAP.

This passes on el7.4 (3.10.0-693.el7.x86_64), explodes in el7.5 (3.10.0-830.el7.x86_64)
iproute-3.10.0-87.el7.x86_64 version running on both kernels 


ip link add type veth
ip link add type veth
brctl delbr pm2
brctl addbr pm2

/sbin/tc qdisc add dev pm2 ingress
/sbin/tc filter show dev pm2 parent ffff:
/sbin/tc filter replace dev pm2 protocol all parent ffff: u32 match u8 0 0 action mirred egress mirror dev veth0
/sbin/tc qdisc replace dev pm2 root prio
qd=`/sbin/tc qdisc show dev pm2 |grep '^qdisc prio ' |sed 's/qdisc prio //;s/: .*//'`

/sbin/tc filter show dev pm2 parent "$qd":
/sbin/tc filter replace dev pm2 protocol all parent "$qd": u32 match u8 0 0 action mirred egress mirror dev veth0
/sbin/ip link set dev pm2 promisc on

/sbin/tc qdisc add dev pm2 ingress || :
/sbin/tc filter show dev pm2 parent ffff:
/sbin/tc filter replace dev pm2 protocol all parent ffff: handle 800::800 pref 49152 u32 match u8 0 0 action mirred egress mirror dev veth0 action mirred egress mirror dev veth2


[root@camel-vdsa ~]# bash -ex burman.sh
+ brctl delbr pm2
+ brctl addbr pm2
+ /sbin/tc qdisc add dev pm2 ingress
+ /sbin/tc filter show dev pm2 parent ffff:
+ /sbin/tc filter replace dev pm2 protocol all parent ffff: u32 match u8 0 0 action mirred egress mirror dev veth0
+ /sbin/tc qdisc replace dev pm2 root prio
++ /sbin/tc qdisc show dev pm2
++ grep '^qdisc prio '
++ sed 's/qdisc prio //;s/: .*//'
+ qd=8010
+ /sbin/tc filter show dev pm2 parent 8010:
+ /sbin/tc filter replace dev pm2 protocol all parent 8010: u32 match u8 0 0 action mirred egress mirror dev veth0
+ /sbin/ip link set dev pm2 promisc on
+ /sbin/tc qdisc add dev pm2 ingress
RTNETLINK answers: File exists
+ :
+ /sbin/tc filter show dev pm2 parent ffff:
filter protocol all pref 49152 u32 
filter protocol all pref 49152 u32 fh 800: ht divisor 1 
filter protocol all pref 49152 u32 fh 800::800 order 2048 key ht 800 bkt 0 terminal flowid ??? not_in_hw 
  match 00000000/00000000 at 0
        action order 1: mirred (Egress Mirror to device veth0) pipe
        index 1 ref 1 bind 1
 
+ /sbin/tc filter replace dev pm2 protocol all parent ffff: handle 800::800 pref 49152 u32 match u8 0 0 action mirred egress mirror dev veth0 action mirred egress mirror dev veth2
RTNETLINK answers: Invalid argument
We have an error talking to the kernel

Given the commandline-only reproducer, I'm moving the bug to RHEL.

The issue is caused by commit:

commit 24d3dc6d27eae19f422a5e216e25d3a16628d4ff
Author: Or Gerlitz <ogerlitz>
Date:   Thu Feb 16 10:31:15 2017 +0200

    net/sched: cls_u32: Reflect HW offload status
    
    U32 support for the "in hw" offloading flags.
    
    Signed-off-by: Or Gerlitz <ogerlitz>
    Reviewed-by: Amir Vadai <amir>
    Signed-off-by: David S. Miller <davem>

This commit added TCA_CLS_FLAGS_{,NOT}_IN_HW flags to u32 but the conditional in u32_change() is too strict and causes impossibility to replace existing filter:

static int u32_change(struct net *net, struct sk_buff *in_skb,
                      struct tcf_proto *tp, unsigned long base, u32 handle,
                      struct nlattr **tca, void **arg, bool ovr,
                      struct netlink_ext_ack *extack)
{
...
                if (n->flags != flags) {
                        NL_SET_ERR_MSG_MOD(extack, "Key node flags do not match passed flags");
                        return -EINVAL;
                }
...
}

The n->flags contains either ...IN_HW or ...NOT_IN_HW according offloading state. These flags cannot be passed from userspace so the passed flags cannot contain them and the conditional cannot be true.

The upstream is affected as well so I'm going to fix it first.

Upstream patch submitted:

https://patchwork.ozlabs.org/patch/870905/

(In reply to Ivan Vecera from comment #8)
> Upstream patch submitted:
> 
> https://patchwork.ozlabs.org/patch/870905/

Accepted.

Done

May I ask when would we have a build to test?

Patch(es) committed on kernel repository and an interim kernel build is undergoing testing

Patch(es) available on kernel-3.10.0-854.el7

ovirt-engine-4.2.2.1-0.1.el7.noarch
kernel 3.10.0-855.el7.x86_64

ovirt-engine-4.2.2.1-0.1.el7.noarch
kernel 3.10.0-855.el7.x86_64

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHSA-2018:1062