linux-kernel - Re: [PATCH v1 06/12] trace: use TP_printk_no

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Message-ID: <20231106194500.123a517e@gandalf.local.home>
Date:   Mon, 6 Nov 2023 19:45:00 -0500
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Łukasz Bartosik <lb@...ihalf.com>
Cc:     Jason Baron <jbaron@...mai.com>, Jim Cromie <jim.cromie@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Kees Cook <keescook@...omium.org>,
        Douglas Anderson <dianders@...omium.org>,
        Guenter Roeck <groeck@...gle.com>,
        Yaniv Tzoreff <yanivt@...gle.com>,
        Benson Leung <bleung@...gle.com>,
        Vincent Whitchurch <vincent.whitchurch@...s.com>,
        Pekka Paalanen <ppaalanen@...il.com>,
        Sean Paul <seanpaul@...omium.org>,
        Daniel Vetter <daniel@...ll.ch>, linux-kernel@...r.kernel.org,
        upstream@...ihalf.com
Subject: Re: [PATCH v1 06/12] trace: use TP_printk_no_nl in
 dyndbg:prdbg,devdbg

On Fri,  3 Nov 2023 14:10:05 +0100
Łukasz Bartosik <lb@...ihalf.com> wrote:

> index ccc5bcb070f9..91dcdbe059c0 100644
> --- a/include/trace/events/dyndbg.h
> +++ b/include/trace/events/dyndbg.h
> @@ -20,20 +20,10 @@ TRACE_EVENT(prdbg,
>  
>  	    TP_fast_assign(
>  			__entry->desc = desc;
> -			/*
> -			 * Each trace entry is printed in a new line.
> -			 * If the msg finishes with '\n', cut it off
> -			 * to avoid blank lines in the trace.
> -			 */
> -			if (len > 0 && (text[len - 1] == '\n'))
> -				len -= 1;
> -
>  			memcpy(__get_str(msg), text, len);
> -			__get_str(msg)[len] = 0;
>  		    ),
>  
> -	    TP_printk("%s.%s %s", __entry->desc->modname,
> -		      __entry->desc->function, __get_str(msg))
> +	    TP_printk_no_nl("%s", __get_str(msg))
>  );
>  

Instead of adding the TP_printk_no_nl() (Which I still do not like), we
could add a:

	__get_str_strip_nl(msg)

That will do the above loop. Which will move the processing to read side
(slow path).

And then we could update libtraceevent to handle that too.

-- Steve