Date: Wed, 7 Jan 2004 13:56:24 -0800
From: Greg KH <greg@kroah.com>
To: Alan Stern <stern@rowland.harvard.edu>
Cc: Kernel development list <linux-kernel@vger.kernel.org>,
       Patrick Mochel <mochel@digitalimplant.org>
Subject: Re: Inconsistency in sysfs behavior?
Message-ID: <20040107215624.GC1083@kroah.com>
References: <20040107172750.GC31177@kroah.com> <Pine.LNX.4.44L0.0401071644220.1589-100000@ida.rowland.org>
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On Wed, Jan 07, 2004 at 04:50:24PM -0500, Alan Stern wrote:
> On Wed, 7 Jan 2004, Greg KH wrote:
> 
> > Because it is very difficult to determine when a user goes into a
> > directory because we are using the ramfs/libfs code.  It also does not
> > cause any errors if the kobject is removed, as the vfs cleans up
> > properly.
> > 
> > Only when a file is opened does a kobject need to be pinned, due to
> > possible errors that could happen.
> 
> I had in mind approaching this the opposite way.  Instead of trying to 
> make open directories also pin a kobject, why not make open attribute 
> files not pin them?
> 
> It shouldn't be hard to avoid any errors; in fact I had a patch from some
> time ago that would do the trick (although in a hacked-up kind of way).  
> The main idea is to return -ENXIO instead of calling the show()/store()
> routines once the attribute has been removed.

And you can do this without adding another lock, race free?

greg k-h
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