Re: [linux-usb-devel] Re: Linux 2.6.16-rc3

[Greg KH]

On Wed, Feb 15, 2006 at 05:25:37PM -0500, Alan Stern wrote:
> On Wed, 15 Feb 2006, Greg KH wrote:
> 
> > On Wed, Feb 15, 2006 at 04:52:43PM -0500, Alan Stern wrote:
> > > On Wed, 15 Feb 2006, Greg KH wrote:
> > > 
> > > > On Wed, Feb 15, 2006 at 05:35:08PM +0100, Arjan van de Ven wrote:
> > > > > On Wed, 2006-02-15 at 08:27 -0800, Greg KH wrote:
> > > > > > 
> > > > > > Nah, I don't think it's a good idea.  James's patch should work just
> > > > > > fine.
> > > > > 
> > > > > another option is to have a "kill list" which you put the thing on, and
> > > > > then wake up a thread. only 2 pointers in the object ;(
> > > > 
> > > > Hm, that's almost what James's patch is trying to do.  Care to mock up a
> > > > patch that shows this?  It might be a simpler solution.
> > > 
> > > It won't work.  You might have to do 2 put_device calls on the same 
> > > structure.  That's why I suggested the "pending puts" counter; something 
> > > can't go on a list more than once.
> > 
> > It would only go on the list if the "put" was the last one.  Otherwise
> > it would not make any sense to put it on any list.
> 
> There's no way to know whether or not any particular "put" is the last 
> one.  So you have to assume they all are.

The underlying kobject can "know" that the put was the last one, and
handle it differently if needed.  Yes, it would not use a kref anymore,
but that might be needed here.

thanks,

greg k-h
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