netdev - Re: [PATCH] net: openvswitch: introduce common code for flushing flows

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Date:   Tue, 11 Aug 2020 17:47:59 -0700
From:   Cong Wang <xiyou.wangcong@...il.com>
To:     Tonghao Zhang <xiangxia.m.yue@...il.com>
Cc:     Joel Fernandes <joel@...lfernandes.org>,
        Johan Knöös <jknoos@...gle.com>,
        Gregory Rose <gvrose8192@...il.com>,
        "Uladzislau Rezki (Sony)" <urezki@...il.com>,
        "Paul E . McKenney" <paulmck@...nel.org>, dev@...nvswitch.org,
        Linux Kernel Network Developers <netdev@...r.kernel.org>,
        rcu <rcu@...r.kernel.org>
Subject: Re: [PATCH] net: openvswitch: introduce common code for flushing flows

On Mon, Aug 10, 2020 at 6:14 PM <xiangxia.m.yue@...il.com> wrote:
>
> From: Tonghao Zhang <xiangxia.m.yue@...il.com>
>
> To avoid some issues, for example RCU usage warning, we should
> flush the flows under ovs_lock. This patch refactors
> table_instance_destroy and introduces table_instance_flow_flush
> which can be invoked by __dp_destroy or ovs_flow_tbl_flush.
>
> Signed-off-by: Tonghao Zhang <xiangxia.m.yue@...il.com>

Please add a Fixes tag here, I think it is probably your memory leak fix
which introduced this issue. And a Reported-by, to give credits to bug
reporters.

Plus one minor issue below:

> -static void table_instance_destroy(struct flow_table *table,
> -                                  struct table_instance *ti,
> -                                  struct table_instance *ufid_ti,
> -                                  bool deferred)
> +/* Must be called with OVS mutex held. */
> +void table_instance_flow_flush(struct flow_table *table,
> +                              struct table_instance *ti,
> +                              struct table_instance *ufid_ti)
>  {
>         int i;
>
> -       if (!ti)
> -               return;
> -
> -       BUG_ON(!ufid_ti);
>         if (ti->keep_flows)
> -               goto skip_flows;
> +               return;
>
>         for (i = 0; i < ti->n_buckets; i++) {
> -               struct sw_flow *flow;
>                 struct hlist_head *head = &ti->buckets[i];
>                 struct hlist_node *n;
> +               struct sw_flow *flow;

This is at most a coding style change, please do not mix
coding style changes in bug fixes. You can always push coding
style changes separately when net-next is open.

Thanks.