Messages in this thread | | | Date | Sun, 26 Oct 2008 12:34:13 -0600 | From | Matthew Wilcox <> | Subject | Re: [PATCH] pci: Fixing drivers/pci/search.c compilation warning. |
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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."
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