Re: [PATCH v1 2/2] tap, tcp, udp: Use rate-limited logging

[David Gibson <david@gibson.dropbear.id.au>]

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On Mon, Apr 06, 2026 at 10:12:48AM +0200, Stefano Brivio wrote:
> On Wed,  1 Apr 2026 23:59:10 +0530
> Anshu Kumari <anskuma@redhat.com> wrote:
> 
> > Now that rate-limited logging macros are available, promote several
> > debug messages to higher severity levels.  These messages were
> > previously kept at debug to prevent guests from flooding host
> > logs, but with rate limiting they can safely be made visible in
> > normal operation.
> > 
> > In tap.c, refactor tap4_is_fragment() to use warn_ratelimit() instead
> > of its ad-hoc rate limiting, and promote the guest MAC address change
> > message to info level.
> > 
> > In tcp.c, promote the invalid TCP SYN endpoint message to warn level.
> > 
> > In udp.c and udp_flow.c, promote flow allocation failures and dropped
> > datagram messages to warn level, and rate-limit the unrecoverable
> > socket error message.
> > 
> > Link: https://bugs.passt.top/show_bug.cgi?id=134
> 
> By the way of this ticket, I forgot to mention that as it came up after
> a discussion on a series by Volker (Volker Diels-Grabsch <v@njh.eu>),
> it would be nice to Cc: him on the next version of this patch.
> 
> > Signed-off-by: Anshu Kumari <anskuma@redhat.com>
> > ---
> > 
> > - Inside udp.c
> > - David: should this be changed to warn_ratelimit? I am not sure about it
> >   debug("%s error on UDP socket %i: %s",
> >     str_ee_origin(ee), s, strerror_(ee->ee_errno));
> 
> I had a closer look, and it looks like we're hitting that part for any
> error reported via ICMP that can be associated to a given UDP socket, so
> I would say it's part of our regular networking operation, and we
> should keep it as debug().

Thinking about this again, I agree.  Looking at this another way, the
error is already being reported at the right level: as an ICMP message
to the guest.  At the passt level this might be useful for debugging,
hence debug() but doesn't represent anything out of the ordinary or
worrying.

-- 
David Gibson (he or they)	| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you, not the other way
				| around.
http://www.ozlabs.org/~dgibson

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