From 97310c32bb83a5240cd527478159934d4aa5f78b Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Tue, 11 Apr 2017 17:33:12 +0100 Subject: PCI: Do not disregard parent resources starting at 0x0 Commit f44116ae8818 ("PCI: Remove pci_find_parent_resource() use for allocation") updated the logic that iterates over all bus resources and compares them to a given resource, in order to decide whether one is the parent of the latter. This change inadvertently causes pci_find_parent_resource() to disregard resources starting at address 0x0, resulting in an error such as the one below on ARM systems whose I/O window starts at 0x0. pci_bus 0000:00: root bus resource [mem 0x10000000-0x3efeffff window] pci_bus 0000:00: root bus resource [io 0x0000-0xffff window] pci_bus 0000:00: root bus resource [mem 0x8000000000-0xffffffffff window] pci_bus 0000:00: root bus resource [bus 00-0f] pci 0000:00:01.0: PCI bridge to [bus 01] pci 0000:00:02.0: PCI bridge to [bus 02] pci 0000:00:03.0: PCI bridge to [bus 03] pci 0000:00:03.0: can't claim BAR 13 [io 0x0000-0x0fff]: no compatible bridge window pci 0000:03:01.0: can't claim BAR 0 [io 0x0000-0x001f]: no compatible bridge window While this never happens on x86, it is perfectly legal in general for a PCI MMIO or IO window to start at address 0x0, and it was supported in the code before commit f44116ae8818. Drop the test for res->start != 0; resource_contains() already checks whether [start, end) completely covers the resource, and so it should be redundant. Signed-off-by: Ard Biesheuvel Signed-off-by: Bjorn Helgaas diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index e7d4048..9d840e7 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -454,7 +454,7 @@ struct resource *pci_find_parent_resource(const struct pci_dev *dev, pci_bus_for_each_resource(bus, r, i) { if (!r) continue; - if (res->start && resource_contains(r, res)) { + if (resource_contains(r, res)) { /* * If the window is prefetchable but the BAR is -- cgit v0.10.2