linux-kernel - Re: [ltt-dev] [PATCH 1/2] Make lttctl mount debugfs automatically

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Date:	Thu, 8 Jan 2009 22:30:22 -0500
From:	Mathieu Desnoyers <compudj@...stal.dyndns.org>
To:	Zhaolei <zhaolei@...fujitsu.com>
Cc:	ltt-dev@...ts.casi.polymtl.ca, linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...l.org>, Greg KH <gregkh@...e.de>
Subject: Re: [ltt-dev] [PATCH 1/2] Make lttctl mount debugfs automatically

* Zhaolei (zhaolei@...fujitsu.com) wrote:
> * From: "Mathieu Desnoyers" <compudj@...stal.dyndns.org>
> >* Zhaolei (zhaolei@...fujitsu.com) wrote:
> >> * From: "Pierre-Marc Fournier" <pierre-marc.fournier@...ymtl.ca>
> >> > Zhaolei wrote:
> >> >> lttctl need debugfs mounted,
> >> >> This patch make lttctl mount debugfs automatically when it is not mounted.
> >> >> 
> >> > 
> >> > Isn't having a utility such as lttctl mount filesystems against standard
> >> > unix semantics? Can you give an example of another standard command that
> >> > uses a filesystem and that tries to mount it if it isn't already
> >> > mounted? 
> >> Hello, Pierre-Marc,
> >> 
> >> I can give a an example.
> >> It is SystemTap.
> >> 
> > 
> > No offence, but can you find an example which is not explicitly
> > described as "bad taste" example by many people in the Linux kernel
> > community ?
> Hello, Mathieu
> 
> I can't find another example of mounting debugfs automatically.
> Maybe it is because debugfs is not widely used as others such as sysfs and
> procfs.
> 
> sysfs and procfs are mounted in boot, and user-mode tools need not check and
> mount then again. But debugfs is not too useful for normal user who just use
> linux to edit text and browse internet, so mount debugfs in boot period is not
> a good idea.
> So, IMHO, debugfs's usage is not same as sysfs and procfs, we need not mount
> sysfs and procfs in user-mode program, but maybe it is different for debugfs.
> 
> On the other hand, I also understand your opinion, mount a fs in program looks
> strange(but can make user easy to use...), so you can feel free to ignore this
> patch.
> Same with [PATCH 2/2] Make lttctl load ltt-trace-control module automatically.
> 

I wonder what's Greg KH (and others) opinion about this ?

Mathieu

> Regards
> Zhaolei
> 
> > 
> > Mathieu
> > 
> >> Regards
> >> Zhaolei
> >> 
> >> > My guess is we should warn about the filesystem not being
> >> > mounted, but not try to call mount() directly.
> >> > 
> >> >> Little cleanup also done(combile 2 getdebugfsmntdir() into one).
> >> >> 
> >> >> Applies on top of ltt-control-0.63-03012009.
> >> >> 
> >> > 
> >> >
> >> _______________________________________________
> >> ltt-dev mailing list
> >> ltt-dev@...ts.casi.polymtl.ca
> >> http://lists.casi.polymtl.ca/cgi-bin/mailman/listinfo/ltt-dev
> >> 
> > 
> > -- 
> > Mathieu Desnoyers
> > OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68
> > 
> >
> _______________________________________________
> ltt-dev mailing list
> ltt-dev@...ts.casi.polymtl.ca
> http://lists.casi.polymtl.ca/cgi-bin/mailman/listinfo/ltt-dev
> 

-- 
Mathieu Desnoyers
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68
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