Re: [patchset] Lockfree fd lookup 2 of 5

[Ravikiran G Thirumalai]

On Mon, Aug 02, 2004 at 11:44:24PM -0700, Greg KH wrote:
> On Mon, Aug 02, 2004 at 03:46:06PM +0530, Ravikiran G Thirumalai wrote:
> > diff -ruN -X dontdiff2 linux-2.6.7/drivers/usb/core/message.c kref-2.6.7/drivers/usb/core/message.c
> > --- linux-2.6.7/drivers/usb/core/message.c	2004-06-16 10:49:02.000000000 +0530
> > +++ kref-2.6.7/drivers/usb/core/message.c	2004-07-20 15:07:24.000000000 +0530
> > @@ -1077,11 +1077,12 @@
> >  
> >  static void release_interface(struct device *dev)
> >  {
> > +	extern void destroy_serial(struct kref *kref);
> >  	struct usb_interface *intf = to_usb_interface(dev);
> >  	struct usb_interface_cache *intfc =
> >  			altsetting_to_usb_interface_cache(intf->altsetting);
> >  
> > -	kref_put(&intfc->ref);
> > +	kref_put(&intfc->ref, destroy_serial);
> >  	kfree(intf);
> >  }
> 
> This is the bug.  destroy_serial() is for the usb_serial core and does
> not clean up for this type of structure (and is not exported, so it will
> not even build properly).  Also, never put a function prototype within a
> function like you did here.
> 
> So, I'm guessing you didn't try to remove any USB devices after applying
> your patch?  :)

No I didn't :).  I just checked the build not the working as such.  
>From what I could infer from the 2.6.7 tree, there is no kref_init()
in core/message.c.  Well I dunno what made me think destroy_serial
was used to init (kref_init) that refcounter at that time so I have 
even exported destroy_serial in the patch so that it builds.  
(expored as in changing static to non static .. I build all drivers 
into the kernel usually and so the build didn't break for me).
I now realise destroy_serial is the wrong release function.  I am no expert 
in usb-drivers area, but I should be more careful than that. 

Thanks,
Kiran
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