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Date:   Fri, 15 Jul 2022 17:44:22 -0400
From:   Steven Rostedt <rostedt@goodmis.org>
To:     linux-kernel@vger.kernel.org
Cc:     Ingo Molnar <mingo@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Dennis Dalessandro <dennis.dalessandro@cornelisnetworks.com>,
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        Eric Dumazet <edumazet@google.com>,
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        Antonio Quartulli <a@unstable.cc>,
        Sven Eckelmann <sven@narfation.org>,
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        Jim Cromie <jim.cromie@gmail.com>
Subject: Re: [PATCH 01/13 v2] tracing/events: Add __vstring() and
 __assign_vstr() helper macros
Message-ID: <20220715174422.6bf21fc2@gandalf.local.home>
In-Reply-To: <20220715174214.22314a87@gandalf.local.home>
References: <20220705224453.120955146@goodmis.org>
        <20220705224749.053570613@goodmis.org>
        <20220715174214.22314a87@gandalf.local.home>
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On Fri, 15 Jul 2022 17:42:14 -0400
Steven Rostedt <rostedt@goodmis.org> wrote:

> It uses the helper:
> 
>  #define __trace_event_vstr_len(fmt, va)	\
>  ({						\
> 	va_list __ap;				\
> 	int __ret;				\
> 						\
> 	va_copy(__ap, *(va));			\
> 	__ret = vsnprintf(NULL, 0, fmt, __ap);	\
> 	va_end(__ap);				\
> 						\
> 	min(__ret, TRACE_EVENT_STR_MAX);	\
>  })

I forgot to mention what is different in v2. I fixed what happened to be in
the change log, as there was an off by one error. I just updated the change
log in my git repo to have the above be:

It uses the helper:

 #define __trace_event_vstr_len(fmt, va)                \
 ({                                                     \
        va_list __ap;                                   \
        int __ret;                                      \
                                                        \
        va_copy(__ap, *(va));                           \
        __ret = vsnprintf(NULL, 0, fmt, __ap) + 1;      \
        va_end(__ap);                                   \
                                                        \
        min(__ret, TRACE_EVENT_STR_MAX);                \
 })


-- Steve