netdev - Re: [PATCH net v3] net/sched: cls_api: Fix nooffloaddevcnt counter when indr block call success

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Date:   Thu, 19 Sep 2019 15:50:17 +0300
From:   Or Gerlitz <gerlitz.or@...il.com>
To:     wenxu@...oud.cn,
        Pieter Jansen van Vuuren 
        <pieter.jansenvanvuuren@...ronome.com>,
        Oz Shlomo <ozsh@...lanox.com>
Cc:     David Miller <davem@...emloft.net>,
        Linux Netdev List <netdev@...r.kernel.org>,
        Roi Dayan <roid@...lanox.com>,
        Paul Blakey <paulb@...lanox.com>,
        Jiri Pirko <jiri@...lanox.com>
Subject: Re: [PATCH net v3] net/sched: cls_api: Fix nooffloaddevcnt counter
 when indr block call success

On Thu, Sep 19, 2019 at 11:39 AM <wenxu@...oud.cn> wrote:
>
> From: wenxu <wenxu@...oud.cn>
>
> A vxlan or gretap device offload through indr block methord. If the device

nit: method --> method

> successfully bind with a real hw through indr block call, It also add
> nooffloadcnt counter. This counter will lead the rule add failed in
> fl_hw_replace_filter-->tc_setup_cb_call with skip_sw flags.

wait.. indirect tc callbacks are typically used to do hw offloading
for decap rules (tunnel key unset action) set on SW devices (gretap, vxlan).

However, AFAIK, it's been couple of years since the kernel doesn't support
skip_sw for such rules. Did we enable it again? when? I am somehow
far from the details, so copied some folks..

Or.


>
> In the tc_setup_cb_call will check the nooffloaddevcnt and skip_sw flags
> as following:
> if (block->nooffloaddevcnt && err_stop)
>         return -EOPNOTSUPP;
>
> So with this patch, if the indr block call success, it will not modify
> the nooffloaddevcnt counter.
>
> Fixes: 7f76fa36754b ("net: sched: register callbacks for indirect tc block binds")
> Signed-off-by: wenxu <wenxu@...oud.cn>
> ---
> v3: rebase to the net
>
>  net/sched/cls_api.c | 30 +++++++++++++++++-------------
>  1 file changed, 17 insertions(+), 13 deletions(-)
>
> diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
> index 32577c2..c980127 100644
> --- a/net/sched/cls_api.c
> +++ b/net/sched/cls_api.c
> @@ -607,11 +607,11 @@ static void tc_indr_block_get_and_ing_cmd(struct net_device *dev,
>         tc_indr_block_ing_cmd(dev, block, cb, cb_priv, command);
>  }
>
> -static void tc_indr_block_call(struct tcf_block *block,
> -                              struct net_device *dev,
> -                              struct tcf_block_ext_info *ei,
> -                              enum flow_block_command command,
> -                              struct netlink_ext_ack *extack)
> +static int tc_indr_block_call(struct tcf_block *block,
> +                             struct net_device *dev,
> +                             struct tcf_block_ext_info *ei,
> +                             enum flow_block_command command,
> +                             struct netlink_ext_ack *extack)
>  {
>         struct flow_block_offload bo = {
>                 .command        = command,
> @@ -621,10 +621,15 @@ static void tc_indr_block_call(struct tcf_block *block,
>                 .block_shared   = tcf_block_shared(block),
>                 .extack         = extack,
>         };
> +
>         INIT_LIST_HEAD(&bo.cb_list);
>
>         flow_indr_block_call(dev, &bo, command);
> -       tcf_block_setup(block, &bo);
> +
> +       if (list_empty(&bo.cb_list))
> +               return -EOPNOTSUPP;
> +
> +       return tcf_block_setup(block, &bo);
>  }
>
>  static bool tcf_block_offload_in_use(struct tcf_block *block)
> @@ -681,8 +686,6 @@ static int tcf_block_offload_bind(struct tcf_block *block, struct Qdisc *q,
>                 goto no_offload_dev_inc;
>         if (err)
>                 goto err_unlock;
> -
> -       tc_indr_block_call(block, dev, ei, FLOW_BLOCK_BIND, extack);
>         up_write(&block->cb_lock);
>         return 0;
>
> @@ -691,9 +694,10 @@ static int tcf_block_offload_bind(struct tcf_block *block, struct Qdisc *q,
>                 err = -EOPNOTSUPP;
>                 goto err_unlock;
>         }
> +       err = tc_indr_block_call(block, dev, ei, FLOW_BLOCK_BIND, extack);
> +       if (err)
> +               block->nooffloaddevcnt++;
>         err = 0;
> -       block->nooffloaddevcnt++;
> -       tc_indr_block_call(block, dev, ei, FLOW_BLOCK_BIND, extack);
>  err_unlock:
>         up_write(&block->cb_lock);
>         return err;
> @@ -706,8 +710,6 @@ static void tcf_block_offload_unbind(struct tcf_block *block, struct Qdisc *q,
>         int err;
>
>         down_write(&block->cb_lock);
> -       tc_indr_block_call(block, dev, ei, FLOW_BLOCK_UNBIND, NULL);
> -
>         if (!dev->netdev_ops->ndo_setup_tc)
>                 goto no_offload_dev_dec;
>         err = tcf_block_offload_cmd(block, dev, ei, FLOW_BLOCK_UNBIND, NULL);
> @@ -717,7 +719,9 @@ static void tcf_block_offload_unbind(struct tcf_block *block, struct Qdisc *q,
>         return;
>
>  no_offload_dev_dec:
> -       WARN_ON(block->nooffloaddevcnt-- == 0);
> +       err = tc_indr_block_call(block, dev, ei, FLOW_BLOCK_UNBIND, NULL);
> +       if (err)
> +               WARN_ON(block->nooffloaddevcnt-- == 0);
>         up_write(&block->cb_lock);
>  }
>
> --
> 1.8.3.1
>