Re: [PATCH] pci: Fixing drivers/pci/search.c compilation warning.

["Zhao, Yu" <yu.zhao@intel.com>]

Matthew Wilcox wrote:
> On Mon, Oct 27, 2008 at 11:18:43AM +0800, Zhao, Yu wrote:
>> Matthew Wilcox wrote:
>>> Yes, that's why pci_find_device() is deprecated.  But it doesn't also
>>> need to be buggy ;-)
>> How about pci_get_bus_and_slot()? People would meet the problem with it 
>> anyway.
> 
> What problem with it?  It's documented to return the device with an
> increased refcount, and the implementation appears to do exactly that:
> 
> struct pci_dev * pci_get_bus_and_slot(unsigned int bus, unsigned int devfn)
> {
>         struct pci_dev *dev = NULL;
> 
>         while ((dev = pci_get_device(PCI_ANY_ID, PCI_ANY_ID, dev)) != NULL) {
>                 if (pci_domain_nr(dev->bus) == 0 &&
>                    (dev->bus->number == bus && dev->devfn == devfn))
>                         return dev;
>         }
>         return NULL;
> }
> 
> Are you saying some users of it neglect to decrement the refcount before
> disposing of the device?
> 

The 'dev' returned by pci_get_device() may be destroyed by PCI hotplug. 
I suppose that passing this 'dev' to pci_get_device() in the next loop 
would crash the system, right?