netdev - Re: [PATCH net] net/sched: cls_flower: Avoid attempt to delete from hw a flow which was not offloaded

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Message-ID: <20171025141614.GC1976@nanopsycho.orion>
Date:   Wed, 25 Oct 2017 16:16:14 +0200
From:   Jiri Pirko <jiri@...nulli.us>
To:     Or Gerlitz <ogerlitz@...lanox.com>
Cc:     "David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org,
        Jiri Pirko <jiri@...lanox.com>, mlxsw@...lanox.com,
        Roi Dayan <roid@...lanox.com>, Paul Blakey <paulb@...lanox.com>
Subject: Re: [PATCH net] net/sched: cls_flower: Avoid attempt to delete from
 hw a flow which was not offloaded

Wed, Oct 25, 2017 at 04:07:26PM CEST, ogerlitz@...lanox.com wrote:
>On 10/25/2017 4:58 PM, Jiri Pirko wrote:
>> Wed, Oct 25, 2017 at 03:44:40PM CEST, ogerlitz@...lanox.com wrote:
>> > If we failed to offload a flow to HW, we should not be attempting to delete
>> > it from the HW. Also, on this case, we should be err-ing only if the flow is
>> > not is SW, fix both issues.
>> > 
>> > Fixes: 717503b9cf57 ('net: sched: convert cls_flower->egress_dev users to tc_setup_cb_egdev infra')
>> > Signed-off-by: Or Gerlitz <ogerlitz@...lanox.com>
>> > ---
>> > net/sched/cls_flower.c | 11 ++++-------
>> > 1 file changed, 4 insertions(+), 7 deletions(-)
>> > 
>> > diff --git a/net/sched/cls_flower.c b/net/sched/cls_flower.c
>> > index 16f58ab..b98e0cb 100644
>> > --- a/net/sched/cls_flower.c
>> > +++ b/net/sched/cls_flower.c
>> > @@ -230,15 +230,12 @@ static int fl_hw_replace_filter(struct tcf_proto *tp,
>> > 
>> > 	err = tc_setup_cb_call(block, &f->exts, TC_SETUP_CLSFLOWER,
>> > 			       &cls_flower, skip_sw);
>> > -	if (err < 0) {
>> > -		fl_hw_destroy_filter(tp, f);
>> > -		return err;
>> 
>> As I wrote in the other thread: Yes, that is intentional. The thing is, there might be multiple block callbacks registered and to be called. If there is a fail with one, we need to cleanup all. So in your case you have 1 cb registered, that means that in case of an error during insertion, you will get cb called to remove. Driver has to take care of that. I was checking that and was under impression that mlx5 deals with that.
>
>I see, what about the other line I deleted of blankly returning err no matter
>regardless if we' re on skip_sw or not, do you agree this fix is needed, also
>see below

No. That is not needed. The current behaviour with the skip_sw is the
same as the original. I don't understand why you want to change it. I
also don't undestand why you do 2 things in one patch.


>> > -	} else if (err > 0) {
>> > +
>> > +	if (err > 0)
>> > 		f->flags |= TCA_CLS_FLAGS_IN_HW;
>> > -	}
>> > 
>> > -	if (skip_sw && !(f->flags & TCA_CLS_FLAGS_IN_HW))
>> > -		return -EINVAL;
>> > +	if (skip_sw)
>> > +		return err;
>> > 
>> > 	return 0;
>> > }
>
>here's too, I don't see why we should return -EINVAL etc, and what's wrong
>with the code as it wad before your patch, I just returned it to how it was
>before which I think is correct
>
>Or.