linux-kernel - Re: [Patch -tip 3/3] Tracing/ftrace: Don't consume entries unhandled by mmiotrace

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Date:	Thu, 25 Sep 2008 17:34:35 +0300
From:	Pekka Paalanen <pq@....fi>
To:	Frédéric Weisbecker <fweisbec@...il.com>,
	Ingo Molnar <mingo@...e.hu>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: [Patch -tip 3/3] Tracing/ftrace: Don't consume entries
 unhandled by mmiotrace

On Thu, 25 Sep 2008 13:28:56 +0100
Frédéric Weisbecker <fweisbec@...il.com> wrote:

> When mmiotrace can't handle an entry output, it returns 1.
> It should return 0 to relay on other output functions.
> 
> Signed-off-by: Frederic Weisbecker <fweisbec@...il.com>
> ---
> diff --git a/kernel/trace/trace_mmiotrace.c b/kernel/trace/trace_mmiotrace.c
> index a108c32..6fe1315 100644
> --- a/kernel/trace/trace_mmiotrace.c
> +++ b/kernel/trace/trace_mmiotrace.c
> @@ -277,7 +277,8 @@ static int mmio_print_line(struct trace_iterator *iter)
>  	case TRACE_PRINT:
>  		return mmio_print_mark(iter);
>  	default:
> -		return 1; /* ignore unknown entries */
> +		return 0; /* ignore unknown entries whithout consuming */
>  	}
>  }

NACK.

mmiotrace's log output is stricly specified, the standard/default
printing functions may NOT be used. The output is supposed to be
machine readable in addition to human readable.

The ftrace infrastructure assumes there is only one active tracer
at a time, therefore destroying unhandled entries is not a problem.

-- 
Pekka Paalanen
http://www.iki.fi/pq/
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