Re: [PATCH 5.10 038/146] mptcp: do not warn on bad input from the network

From: Pavel Machek
Date: Wed Jun 23 2021 - 12:53:33 EST


Hi!

> > > From: Paolo Abeni <pabeni@xxxxxxxxxx>
> > >
> > > [ Upstream commit 61e710227e97172355d5f150d5c78c64175d9fb2 ]
> > >
> > > warn_bad_map() produces a kernel WARN on bad input coming
> > > from the network. Use pr_debug() to avoid spamming the system
> > > log.
> >
> > So... we switched from WARN _ONCE_ to pr_debug, as many times as we
> > detect the problem.
> >
> > Should this be pr_debug_once?
>
> Thank you for double checking this!
>
> In the MPTCP code, we use pr_debug() statements as a debug tool, e.g.
> when enabled, it could print per-packet info with no restriction.
>
> There are (a few) similar use in the plain TCP code.
>
> pr_debug() is not supposed to be enabled on any production system,
> while the WARN_ONCE could trigger automated tools for irrelevant
> network noise.

Correct me if I'm wrong, but I believe pr_debug will result in
messages being stored in the dmesg buffer, even on production
systems.

Best regards,
Pavel
--
http://www.livejournal.com/~pavelmachek

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