Date: Tue, 5 Dec 2006 21:58:43 -0800
From: Greg KH <gregkh@suse.de>
To: Marcel Holtmann <marcel@holtmann.org>
Cc: Greg KH <greg@kroah.com>, linux-kernel@vger.kernel.org,
       Cornelia Huck <cornelia.huck@de.ibm.com>
Subject: Re: [PATCH 32/36] driver core: Introduce device_move(): move a device to a new parent.
Message-ID: <20061206055843.GA12997@suse.de>
References: <11650154181661-git-send-email-greg@kroah.com> <11650154221716-git-send-email-greg@kroah.com> <11650154251022-git-send-email-greg@kroah.com> <11650154282911-git-send-email-greg@kroah.com> <11650154311175-git-send-email-greg@kroah.com> <1165163163.19590.62.camel@localhost> <20061204195859.GB29637@kroah.com> <1165266903.12640.35.camel@localhost> <20061204230511.GA9382@kroah.com> <1165332371.2756.23.camel@localhost>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <1165332371.2756.23.camel@localhost>
User-Agent: Mutt/1.5.13 (2006-08-11)
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 2845
Lines: 69

On Tue, Dec 05, 2006 at 04:26:11PM +0100, Marcel Holtmann wrote:
> Hi Greg,
> 
> > > > > > Provide a function device_move() to move a device to a new parent device. Add
> > > > > > auxilliary functions kobject_move() and sysfs_move_dir().
> > > > > > kobject_move() generates a new uevent of type KOBJ_MOVE, containing the
> > > > > > previous path (DEVPATH_OLD) in addition to the usual values. For this, a new
> > > > > > interface kobject_uevent_env() is created that allows to add further
> > > > > > environmental data to the uevent at the kobject layer.
> > > > > 
> > > > > has this one been tested? I don't get it working. I always get an EINVAL
> > > > > when trying to move the TTY device of a Bluetooth RFCOMM link around.
> > > > 
> > > > I relied on Cornelia to test this.  I think some s390 patches depend on
> > > > this change, right?
> > > 
> > > my pre-condition is that the TTY device has no parent and then we move
> > > it to a Bluetooth ACL link as child. This however is not working or the
> > > TTY change to use device instead of class_device has broken something.
> > 
> > Hm, I don't think the class_device stuff has broken anything, but if you
> > think so, please let me know.
> 
> I was checking why device_move() fails and it seems that the check for
> is_registered is the problem here.
> 
>         if (!device_is_registered(dev)) {
>                 error = -EINVAL;
>                 goto out;
>         }
> 
> The ACL link has been attached to the Bluetooth bus, but for some reason
> it still thinks that it is unregistered. Is this check really needed. I
> think it should be possible to also move devices that are not part of a
> bus, yet. And removing that check makes it work for me.
> 
> And btw. I can't see any s390 patches that are using device_move() at
> the moment.
> 
> > > > > And shouldn't device_move(dev, NULL) re-attach it to the virtual device
> > > > > tree instead of failing?
> > > > 
> > > > Yes, that would be good to have.
> > > 
> > > Cornelia, please fix this, because otherwise we can't detach a device
> > > from its parent. Storing the current virtual parent looks racy to me.
> > 
> > You can always restore the previous "virtual" parent from the
> > information given to you in the device itself.  That is what the code
> > does when it first registers the device.
> > 
> > And yes, I too think it should be fixed.
> 
> My knowledge of the driver model is still limited. Can you fix that
> quickly. This is really needed.

As Cornelia wrote this portion of code, I will wait a bit to recieve a
patch...

Cornelia?

thanks,

greg k-h
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/