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Date: Sun, 25 Jan 2015 18:34:33 +0100
From: Jiri Olsa <jolsa@redhat.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: linux-kernel@vger.kernel.org, Ingo Molnar <mingo@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Jiri Olsa <jolsa@kernel.org>,
        Arnaldo Carvalho de Melo <acme@redhat.com>,
        Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>,
        Namhyung Kim <namhyung@kernel.org>
Subject: Re: [PATCH 5/5] perf: Make perf aware of tracefs
Message-ID: <20150125173433.GA10390@krava.brq.redhat.com>
References: <20150124181330.195149364@goodmis.org>
 <20150124181449.157590751@goodmis.org>
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On Sat, Jan 24, 2015 at 01:13:35PM -0500, Steven Rostedt wrote:

SNIP

> @@ -351,11 +385,15 @@ const char *find_tracing_dir(void)
>  	if (tracing_found)
>  		return tracing;
>  
> -	debugfs = find_debugfs();
> -	if (!debugfs)
> -		return NULL;
> +	debugfs = find_tracefs();
> +	if (!debugfs) {
> +		tracing_dir = "/tracing";
> +		debugfs = find_debugfs();
> +		if (!debugfs)
> +			return NULL;

so this pattern 'try tracefs, if that does not work try debugfs'
is all over the patch.. how about we add new new 'virtual' fs to
encapsulate that, like:

  with followign interface:
    bool tpfs_configured(void);
    const char *tpfs_find_mountpoint(void);
    int tpfs_valid_mountpoint(const char *debugfs);
    char *tpfs_mount(const char *mountpoint);
    extern char tpfs_mountpoint[];

It does not neceserily needs to reside in tools/lib/api/fs/tpfs.[ch],
but I believe we need some form of encapsulation for this.

jirka