PCI: Make pci_scan_slot more robust
Yinghai pointed out that the new pci_scan_slot() crashes when called on an ARI-capable slot that is empty. Fix this by exiting early from pci_scan_slot if there is no device in the slot. Also make next_ari_func() robust against devices not existing in case the ARI capability is corrupt. ARI also requires that the devices be listed in order, so if we find a function listed that is out of order, stop scanning to prevent loops. Signed-off-by: Matthew Wilcox <matthew@wil.cx> Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
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@ -1222,11 +1222,19 @@ EXPORT_SYMBOL(pci_scan_single_device);
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static unsigned next_ari_fn(struct pci_dev *dev, unsigned fn)
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{
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u16 cap;
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unsigned pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_ARI);
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unsigned pos, next_fn;
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if (!dev)
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return 0;
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pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_ARI);
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if (!pos)
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return 0;
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pci_read_config_word(dev, pos + 4, &cap);
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return cap >> 8;
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next_fn = cap >> 8;
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if (next_fn <= fn)
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return 0;
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return next_fn;
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}
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static unsigned next_trad_fn(struct pci_dev *dev, unsigned fn)
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@ -1271,12 +1279,14 @@ int pci_scan_slot(struct pci_bus *bus, int devfn)
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return 0; /* Already scanned the entire slot */
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dev = pci_scan_single_device(bus, devfn);
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if (dev && !dev->is_added) /* new device? */
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if (!dev)
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return 0;
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if (!dev->is_added)
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nr++;
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if (pci_ari_enabled(bus))
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next_fn = next_ari_fn;
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else if (dev && dev->multifunction)
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else if (dev->multifunction)
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next_fn = next_trad_fn;
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for (fn = next_fn(dev, 0); fn > 0; fn = next_fn(dev, fn)) {
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