From 4fb88c1a28a8dc302bdc09858e7cdafc97bef794 Mon Sep 17 00:00:00 2001 From: Matthew Wilcox Date: Sun, 17 Jan 2010 14:01:41 -0700 Subject: [PATCH] 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 Signed-off-by: Jesse Barnes --- drivers/pci/probe.c | 18 ++++++++++++++---- 1 file changed, 14 insertions(+), 4 deletions(-) diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c index 9672760c7ad..233d1c275d9 100644 --- a/drivers/pci/probe.c +++ b/drivers/pci/probe.c @@ -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)) { -- 2.41.0