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 ;-) -- Matthew Wilcox Intel Open Source Technology Centre "Bill, look, we understand that you're interested in selling us this operating system, but compare it to ours. We can't possibly take such a retrograde step." -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
