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

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Message-ID: <20210623165327.GA4150@amd>
Date:   Wed, 23 Jun 2021 18:53:27 +0200
From:   Pavel Machek <pavel@....cz>
To:     Paolo Abeni <pabeni@...hat.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        Mat Martineau <mathew.j.martineau@...ux.intel.com>,
        "David S. Miller" <davem@...emloft.net>,
        Sasha Levin <sashal@...nel.org>
Subject: Re: [PATCH 5.10 038/146] mptcp: do not warn on bad input from the
 network

Hi!

> > > From: Paolo Abeni <pabeni@...hat.com>
> > > 
> > > [ 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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