Re: [Bluez-devel] [PATCH] rfcomm_dev_del is called twice if RFCOMM_HANGUP_NOW flag is used

[Ville Tervo <ville.tervo@nokia.com>]

On Thu, Aug 24, 2006 at 03:29:04PM -0300, ext Ulisses Furquim wrote:
> Hi Ville,
> 
> On 8/24/06, Ville Tervo <ville.tervo@nokia.com> wrote:
> > I noticed that rfcomm_dev_del() may be called twice if
> > RFCOMM_HANGUP_NOW flags is used with RFCOMMRELEASEDEV ioctl.
> 
> I think you're right but we must have the RFCOMM_RELEASE_ONHUP bit set
> on dev->flags also, right?
> 

Yep that is right.

> > I made a patch that checks if dev is still in the device list before
> > calling deleting device.
> > The checking is done now in rfcomm_release_dev. Maybe better place would
> > be rfcomm_dev_del?
> 
> Actually calling list_del_init() on an item thas was already deleted
> with list_del_init() won't hurt anyone but it seems we can mess up the
> reference counting by calling rfcomm_dev_del() twice.
> 
> I think your patch doesn't completely solve the problem because
> rfcomm_dev_get() will hold a reference to the device if we still
> manage to find it on the list and we will have reference counting
> problems too. Adding a call to rfcomm_dev_put() before the call to
> rfcomm_dev_del() in your patch will keep the reference counting
> correct, I guess. Something like this:
> 
>   if ((dev = rfcomm_dev_get(req.dev_id))) {
> 		rfcomm_dev_put(dev);
> 		rfcomm_dev_del(dev);
>   }
> 

You are right.

-- 
Ville


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