netdev - Re: [PATCH net-next v3 2/2] netcons: Add udp send fail statistics to netconsole

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Message-ID: <CAO6EAnWOrzOhHNURLct1tsxLL_gaNT+nWttTk4oPcD66h-xAZg@mail.gmail.com>
Date: Thu, 12 Sep 2024 13:58:12 -0400
From: Maksym Kutsevol <max@...sevol.com>
To: Breno Leitao <leitao@...ian.org>
Cc: "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, 
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, 
	Alex Deucher <alexander.deucher@....com>, Greg Kroah-Hartman <gregkh@...uxfoundation.org>, 
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next v3 2/2] netcons: Add udp send fail statistics to netconsole

Hey Breno,
Thanks for looking into this.

On Thu, Sep 12, 2024 at 1:49 PM Breno Leitao <leitao@...ian.org> wrote:
>
> Hello Maksym,
>
> Thanks for the patch, it is looking good. A few nits:
>
> On Thu, Sep 12, 2024 at 10:28:52AM -0700, Maksym Kutsevol wrote:
> > +/**
> > + * netpoll_send_udp_count_errs - Wrapper for netpoll_send_udp that counts errors
> > + * @nt: target to send message to
> > + * @msg: message to send
> > + * @len: length of message
> > + *
> > + * Calls netpoll_send_udp and classifies the return value. If an error
> > + * occurred it increments statistics in nt->stats accordingly.
> > + * Only calls netpoll_send_udp if CONFIG_NETCONSOLE_DYNAMIC is disabled.
> > + */
> > +static void netpoll_send_udp_count_errs(struct netconsole_target *nt, const char *msg, int len)
> > +{
> > +     int result = netpoll_send_udp(&nt->np, msg, len);
>
> Would you get a "variable defined but not used" type of eror if
> CONFIG_NETCONSOLE_DYNAMIC is disabled?
>
Most probably yes, I'll check. If so, I'll add __maybe_unused in the
next iteration.

> > +
> > +     if (IS_ENABLED(CONFIG_NETCONSOLE_DYNAMIC)) {
> > +             if (result == NET_XMIT_DROP) {
> > +                     u64_stats_update_begin(&nt->stats.syncp);
> > +                     u64_stats_inc(&nt->stats.xmit_drop_count);
> > +                     u64_stats_update_end(&nt->stats.syncp);
> > +             } else if (result == -ENOMEM) {
> > +                     u64_stats_update_begin(&nt->stats.syncp);
> > +                     u64_stats_inc(&nt->stats.enomem_count);
> > +                     u64_stats_update_end(&nt->stats.syncp);
> > +             }
> > +     }
>
> Would this look better?
>
>         if (IS_ENABLED(CONFIG_NETCONSOLE_DYNAMIC)) {
>                 u64_stats_update_begin(&nt->stats.syncp);
>
>                 if (result == NET_XMIT_DROP)
>                         u64_stats_inc(&nt->stats.xmit_drop_count);
>                 else if (result == -ENOMEM)
>                         u64_stats_inc(&nt->stats.enomem_count);
>                 else
>                         WARN_ONCE(true, "invalid result: %d\n", result)
>
>                 u64_stats_update_end(&nt->stats.syncp);
>         }
>
1. It will warn on positive result
2. If the last `else` is removed, it attempts locking when the result
is positive, so I'd not do it this way.



> Thanks
> --breno