netdev - Re: [PATCH net 1/5] net: sched: cls_bpf: Undo tcf_bind

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Message-ID: <ZKUftWakv7v1C4h2@corigine.com>
Date: Wed, 5 Jul 2023 08:45:57 +0100
From: Simon Horman <simon.horman@...igine.com>
To: Jamal Hadi Salim <jhs@...atatu.com>
Cc: Jamal Hadi Salim <hadi@...atatu.com>,
	Victor Nogueira <victor@...atatu.com>, netdev@...r.kernel.org,
	xiyou.wangcong@...il.com, jiri@...nulli.us, davem@...emloft.net,
	edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com,
	pctammela@...atatu.com, kernel@...atatu.com
Subject: Re: [PATCH net 1/5] net: sched: cls_bpf: Undo tcf_bind_filter in
 case of an error

On Tue, Jul 04, 2023 at 05:42:29PM -0400, Jamal Hadi Salim wrote:
> On Tue, Jul 4, 2023 at 5:20 PM Simon Horman <simon.horman@...igine.com> wrote:
> >
> > On Tue, Jul 04, 2023 at 04:55:25PM -0400, Jamal Hadi Salim wrote:
> > > On Tue, Jul 4, 2023 at 4:48 PM Simon Horman <simon.horman@...igine.com> wrote:
> > > >
> > > > On Tue, Jul 04, 2023 at 12:14:52PM -0300, Victor Nogueira wrote:
> > > > > If cls_bpf_offload errors out, we must also undo tcf_bind_filter that
> > > > > was done in cls_bpf_set_parms.
> > > > >
> > > > > Fix that by calling tcf_unbind_filter in errout_parms.
> > > > >
> > > > > Fixes: eadb41489fd2 ("net: cls_bpf: add support for marking filters as hardware-only")
> > > > >
> > > >
> > > > nit: no blank line here.
> > > >
> > > > > Signed-off-by: Victor Nogueira <victor@...atatu.com>
> > > > > Acked-by: Jamal Hadi Salim <jhs@...atatu.com>
> > > > > Reviewed-by: Pedro Tammela <pctammela@...atatu.com>
> > > > > ---
> > > > >  net/sched/cls_bpf.c | 8 ++++++--
> > > > >  1 file changed, 6 insertions(+), 2 deletions(-)
> > > > >
> > > > > diff --git a/net/sched/cls_bpf.c b/net/sched/cls_bpf.c
> > > > > index 466c26df853a..4d9974b1b29d 100644
> > > > > --- a/net/sched/cls_bpf.c
> > > > > +++ b/net/sched/cls_bpf.c
> > > > > @@ -409,7 +409,7 @@ static int cls_bpf_prog_from_efd(struct nlattr **tb, struct cls_bpf_prog *prog,
> > > > >  static int cls_bpf_set_parms(struct net *net, struct tcf_proto *tp,
> > > > >                            struct cls_bpf_prog *prog, unsigned long base,
> > > > >                            struct nlattr **tb, struct nlattr *est, u32 flags,
> > > > > -                          struct netlink_ext_ack *extack)
> > > > > +                          bool *bound_to_filter, struct netlink_ext_ack *extack)
> > > > >  {
> > > > >       bool is_bpf, is_ebpf, have_exts = false;
> > > > >       u32 gen_flags = 0;
> > > > > @@ -451,6 +451,7 @@ static int cls_bpf_set_parms(struct net *net, struct tcf_proto *tp,
> > > > >       if (tb[TCA_BPF_CLASSID]) {
> > > > >               prog->res.classid = nla_get_u32(tb[TCA_BPF_CLASSID]);
> > > > >               tcf_bind_filter(tp, &prog->res, base);
> > > > > +             *bound_to_filter = true;
> > > > >       }
> > > > >
> > > > >       return 0;
> > > > > @@ -464,6 +465,7 @@ static int cls_bpf_change(struct net *net, struct sk_buff *in_skb,
> > > > >  {
> > > > >       struct cls_bpf_head *head = rtnl_dereference(tp->root);
> > > > >       struct cls_bpf_prog *oldprog = *arg;
> > > > > +     bool bound_to_filter = false;
> > > > >       struct nlattr *tb[TCA_BPF_MAX + 1];
> > > > >       struct cls_bpf_prog *prog;
> > > > >       int ret;
> > > >
> > > > Please use reverse xmas tree - longest line to shortest - for
> > > > local variable declarations in Networking code.
> > > >
> > >
> > > I think Ed's tool is actually wrong on this Simon.
> > > The rule I know of is: initializations first then declarations -
> > > unless it is documented elsewhere as not the case.
> >
> > Hi Jamal,
> >
> > That is not my understanding of the rule.
> 
> Something about mixing assignments and declarations being
> cplusplusish. That's always how my fingers think.
> 
> So how would this have been done differently? This is the current patch:
> ----
>         struct cls_bpf_head *head = rtnl_dereference(tp->root);
>         struct cls_bpf_prog *oldprog = *arg;
> +       bool bound_to_filter = false;
>         struct nlattr *tb[TCA_BPF_MAX + 1];
>         struct cls_bpf_prog *prog;
>         int ret;
> ----
> 
> Should the change be?
> ---
>         struct cls_bpf_head *head = rtnl_dereference(tp->root);
>         struct cls_bpf_prog *oldprog = *arg;
>         struct nlattr *tb[TCA_BPF_MAX + 1];
> +       bool bound_to_filter = false;
>         struct cls_bpf_prog *prog;
>         int ret;
> ---
> 
> I dont think my gut or brain would let me type that - but if those are
> them rules then it is Victor doing the typing ;->

Hi Jamal,

Let's not drag this out too long.
But, FWIIW, my understanding is that your 2nd example matches the guidelines.

-- 
pw-bot: under-review