Date: Tue, 22 May 2007 21:25:29 -0700
From: Greg KH <greg@kroah.com>
To: Cornelia Huck <cornelia.huck@de.ibm.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>, Pierre Ossman <drzeus-list@drzeus.cx>,
       LKML <linux-kernel@vger.kernel.org>,
       Kristian H?gsberg <krh@bitplanet.net>
Subject: Re: Race free attributes in sysfs
Message-ID: <20070523042529.GC27329@kroah.com>
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On Tue, May 22, 2007 at 10:38:57AM +0200, Cornelia Huck wrote:
> On Mon, 21 May 2007 21:28:15 +0200,
> Kay Sievers <kay.sievers@vrfy.org> wrote:
> 
> > We could change the driver-core to suppress the creation of an attribute
> > if the attribute's show() or store() method returns something like
> > -ENOENT at registration time?
> > The driver would pass _all_ possible attributes of the device at
> > registration time, but the core would only create the attributes which
> > are implemented for this particular device? Would that work for you?
> > 
> > There are already subsystems who need to do similar things internally
> > (firewire), and it may be nice to add such functionality to the core.
> 
> This sounds a bit hackish (overloading the meaning of the show() and
> store() methods).

Firewire already does this today, it's actually really nice :)

> > You can assign any number of attribute groups to the device. If they
> > don't have a group name, they will all be created directly at the device
> > level. Would that work for you?
> 
> What about generic "conditional attribute groups"? Add a check() method
> which is called just before adding them, and only add them if check()
> returned 0 (or doesn't exist)?

People want this on a per-attribute basis, if you did it on a group
level, we would have a bunch of groups with only one attribute in it,
which would be messy.

thanks,

greg k-h
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