netdev - Re: [PATCH net-next] openvswitch: Print error when ovs_execute

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Date:   Sat, 3 Aug 2019 16:01:47 -0700
From:   Pravin Shelar <pshelar@....org>
To:     Yifeng Sun <pkusunyifeng@...il.com>
Cc:     Linux Kernel Network Developers <netdev@...r.kernel.org>
Subject: Re: [PATCH net-next] openvswitch: Print error when
 ovs_execute_actions() fails

On Thu, Aug 1, 2019 at 2:14 PM Yifeng Sun <pkusunyifeng@...il.com> wrote:
>
> Currently in function ovs_dp_process_packet(), return values of
> ovs_execute_actions() are silently discarded. This patch prints out
> an error message when error happens so as to provide helpful hints
> for debugging.
>
> Signed-off-by: Yifeng Sun <pkusunyifeng@...il.com>
> ---
>  net/openvswitch/datapath.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/net/openvswitch/datapath.c b/net/openvswitch/datapath.c
> index 892287d..603c533 100644
> --- a/net/openvswitch/datapath.c
> +++ b/net/openvswitch/datapath.c
> @@ -222,6 +222,7 @@ void ovs_dp_process_packet(struct sk_buff *skb, struct sw_flow_key *key)
>         struct dp_stats_percpu *stats;
>         u64 *stats_counter;
>         u32 n_mask_hit;
> +       int error;
>
>         stats = this_cpu_ptr(dp->stats_percpu);
>
> @@ -229,7 +230,6 @@ void ovs_dp_process_packet(struct sk_buff *skb, struct sw_flow_key *key)
>         flow = ovs_flow_tbl_lookup_stats(&dp->table, key, &n_mask_hit);
>         if (unlikely(!flow)) {
>                 struct dp_upcall_info upcall;
> -               int error;
>
>                 memset(&upcall, 0, sizeof(upcall));
>                 upcall.cmd = OVS_PACKET_CMD_MISS;
> @@ -246,7 +246,10 @@ void ovs_dp_process_packet(struct sk_buff *skb, struct sw_flow_key *key)
>
>         ovs_flow_stats_update(flow, key->tp.flags, skb);
>         sf_acts = rcu_dereference(flow->sf_acts);
> -       ovs_execute_actions(dp, skb, sf_acts, key);
> +       error = ovs_execute_actions(dp, skb, sf_acts, key);
> +       if (unlikely(error))
> +               net_err_ratelimited("ovs: action execution error on datapath %s: %d\n",
> +                                                       ovs_dp_name(dp), error);
>

I would rather add error counter for better visibility.
If you want to use current approach, can you use net_dbg_ratelimited()
since you want to use this for debugging purpose?

Thanks.