On Sun, 15 May 2016 18:36:03 +0200 Daniel Borkmann <dan...@iogearbox.net> wrote:
> In ingress and clsact qdisc TCA_OPTIONS are ignored, since it's > parameterless. In tc, we add an empty addattr_l(... TCA_OPTIONS, > NULL, 0) to the netlink message nevertheless. This has the > side effect that when someone tries a 'tc qdisc replace' and > already an existing such qdisc is present, tc fails with > EINVAL here. > > Reason is that in the kernel, this invokes qdisc_change() when > such requested qdisc is already present. When TCA_OPTIONS are > passed to modify parameters, it looks whether qdisc implements > .change() callback, and if not present (like in both cases here) > it returns with error. Rather than adding an empty stub to the > kernel that ignores TCA_OPTIONS again, just don't add TCA_OPTIONS > to the netlink message in the first place. > > Before: > > # tc qdisc replace dev foo clsact # first try > # tc qdisc replace dev foo clsact # second one > RTNETLINK answers: Invalid argument > > After: > > # tc qdisc replace dev foo clsact > # tc qdisc replace dev foo clsact > # tc qdisc replace dev foo clsact > > Signed-off-by: Daniel Borkmann <dan...@iogearbox.net> > --- > tc/q_clsact.c | 1 - > tc/q_ingress.c | 1 - > 2 files changed, 2 deletions(-) Applied to net-next
