netdev - Re: [PATCH v12 04/10] ref_tracker: have callers pass output function to pr

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Message-ID: <ee3f6fdb27820654c83cdac9df09e0fe6e43883f.camel@kernel.org>
Date: Fri, 30 May 2025 07:47:00 -0400
From: Jeff Layton <jlayton@...nel.org>
To: Krzysztof Karas <krzysztof.karas@...el.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>, "David S. Miller"	
 <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski	
 <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, Simon Horman	
 <horms@...nel.org>, Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, 
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann
 <tzimmermann@...e.de>, David Airlie <airlied@...il.com>,  Simona Vetter
 <simona@...ll.ch>, Jani Nikula <jani.nikula@...ux.intel.com>, Joonas
 Lahtinen	 <joonas.lahtinen@...ux.intel.com>, Rodrigo Vivi
 <rodrigo.vivi@...el.com>,  Tvrtko Ursulin <tursulin@...ulin.net>, Kuniyuki
 Iwashima <kuniyu@...zon.com>, Qasim Ijaz <qasdev00@...il.com>,  Nathan
 Chancellor	 <nathan@...nel.org>, Andrew Lunn <andrew@...n.ch>,
 linux-kernel@...r.kernel.org, 	netdev@...r.kernel.org,
 dri-devel@...ts.freedesktop.org, 	intel-gfx@...ts.freedesktop.org
Subject: Re: [PATCH v12 04/10] ref_tracker: have callers pass output
 function to pr_ostream()

On Fri, 2025-05-30 at 11:13 +0000, Krzysztof Karas wrote:
> Hi Jeff,
> 
> [...]
> > +static void __ostream_printf pr_ostream_buf(struct ostream *stream, char *fmt, ...)
> > +{
> > +	int ret, len = stream->size - stream->used;
> > +	va_list args;
> > +
> > +	va_start(args, fmt);
> > +	ret = vsnprintf(stream->buf + stream->used, len, fmt, args);
> vsnprintf() technically may return a negative error code.
> In that case, we'd be adding some unwanted values to the
> stream->used. When we encounter an error we could skip
> modifying that field.
> 
> > +	va_end(args);
> > +	stream->used += min(ret, len);
> > +}
> > +
> [...]
> 

Good catch. I'll change this to be:

        va_start(args, fmt);
        ret = vsnprintf(stream->buf + stream->used, len, fmt, args);
        va_end(args);
        if (ret > 0)
                stream->used += min(ret, len);

-- 
Jeff Layton <jlayton@...nel.org>