From: Russell King <rmk@arm.linux.org.uk>
Message-Id: <200012071922.TAA09634@raistlin.arm.linux.org.uk>
Subject: Oops while assigning PCI resources
To: linux-kernel@vger.kernel.org
Date: Thu, 7 Dec 2000 19:22:24 +0000 (GMT)
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Sender: linux-kernel-owner@vger.kernel.org

Hi,

Kernel is 2.4.0-test12-pre7

I'm seeing an oops while assigning PCI resources on an ARM board.  This
board as a PCI to PCI bridge on board without any devices on the second
bus.

Trace is:

Trace; c0013ac0 <pbus_assign_resources+0/e4>
Trace; c0013ba4 <pci_assign_unassigned_resources+0/98>
Trace; c0009f34 <pcibios_init+0/68>
Trace; c0012db4 <pci_init+0/44>
Trace; c00089ec <do_basic_setup+0/54>

The place which is causing the oops is in drivers/pci/setup-bus.c:

        for (ln=bus->children.next; ln != &bus->children; ln=ln->next) {
                struct pci_bus *b = pci_bus_b(ln);

                vvvvvvvvvvvvvvvvvvvvv
                b->resource[0]->start = ranges->io_start = ranges->io_end;
                ^^^^^^^^^^^^^^^^^^^^^
                b->resource[1]->start = ranges->mem_start = ranges->mem_end;

                pbus_assign_resources(b, ranges);

The reason is because b->resource is NULL.  Looking at drivers/pci/pci.c,
when we hit a non-cardbus bridge, we never set b->resource[*] to point to
anything.  We call "pci_add_new_bus" from pci_scan_bridge, but neither
pci_add_new_bus nor pci_scan_bridge sets up the resources.

Unfortunately, the PCI bus code (in drivers/pci/setup-bus.c) seems to
assume that someone somewhere has allocated these resources.
   _____
  |_____| ------------------------------------------------- ---+---+-
  |   |         Russell King        rmk@arm.linux.org.uk      --- ---
  | | | | http://www.arm.linux.org.uk/personal/aboutme.html   /  /  |
  | +-+-+                                                     --- -+-
  /   |               THE developer of ARM Linux              |+| /|\
 /  | | |                                                     ---  |
    +-+-+ -------------------------------------------------  /\\\  |
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