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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: Matthew Wilcox <matthew@wil.cx>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
hifive-unleashed-5.1
Matthew Wilcox 2010-01-17 14:01:41 -07:00 committed by Jesse Barnes
parent 0bf01c3c86
commit 4fb88c1a28
1 changed files with 14 additions and 4 deletions
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18
drivers/pci/probe.c
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@ -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)) {