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Commit 4fb88c1a authored by Matthew Wilcox's avatar Matthew Wilcox Committed by Jesse Barnes
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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: default avatarMatthew Wilcox <matthew@wil.cx>
Signed-off-by: default avatarJesse Barnes <jbarnes@virtuousgeek.org>
parent 0bf01c3c

drivers/pci/probe.c

+14 −4
Original line number Diff line number Diff line
@@ -1222,11 +1222,19 @@ EXPORT_SYMBOL(pci_scan_single_device); 
static unsigned next_ari_fn(struct pci_dev *dev, unsigned fn)

{

	u16 cap;

	unsigned pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_ARI);

	unsigned pos, next_fn;



	if (!dev)

		return 0;



	pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_ARI);

	if (!pos)

		return 0;

	pci_read_config_word(dev, pos + 4, &cap);

	return cap >> 8;

	next_fn = cap >> 8;

	if (next_fn <= fn)

		return 0;

	return next_fn;

}



static unsigned next_trad_fn(struct pci_dev *dev, unsigned fn)
@@ -1271,12 +1279,14 @@ int pci_scan_slot(struct pci_bus *bus, int devfn) 
		return 0; /* Already scanned the entire slot */



	dev = pci_scan_single_device(bus, devfn);

	if (dev && !dev->is_added)	/* new device? */

	if (!dev)

		return 0;

	if (!dev->is_added)

		nr++;



	if (pci_ari_enabled(bus))

		next_fn = next_ari_fn;

	else if (dev && dev->multifunction)

	else if (dev->multifunction)

		next_fn = next_trad_fn;



	for (fn = next_fn(dev, 0); fn > 0; fn = next_fn(dev, fn)) {