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

[Zhao, Yu]

Matthew Wilcox wrote:
> On Sun, Oct 26, 2008 at 08:51:25PM +0800, Yu Zhao wrote:
> > This reminds me of other problems of PCI search functions.
> >
> > The 'dev_start' is passed to bus_find_device(), and its 'knode_bus' 
> > reference count is decreased by klist_iter_init_node() in that function. 
> > The problem is the reference count may be already decrease to 0 because 
> > the PCI device 'from' is hot-plugged off (e.g., pci_remove_bus) when the 
> > search goes. A warning is fired when klist_iter_init_node() detects the 
> > reference count becomes 0.
> >
> > Some code uses pci_find_device() in a way that is not safe with the 
> > hotplug, because a device may be destroyed after bus_find_device() 
> > returns it and before it's held by pci_dev_get() in the next round. 
> > Following is an example from a random grep:
>
> 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.

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