lkml.org 
[lkml]   [2017]   [Dec]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH AUTOSEL for 4.9 096/156] PCI: Do not allocate more buses than available in parent
    Date
    From: Mika Westerberg <mika.westerberg@linux.intel.com>

    [ Upstream commit a20c7f36bd3d20d245616ae223bb9d05dfb6f050 ]

    One can ask more buses to be reserved for hotplug bridges by passing
    pci=hpbussize=N in the kernel command line. If the parent bus does not
    have enough bus space available we incorrectly create child bus with the
    requested number of subordinate buses.

    In the example below hpbussize is set to one more than we have available
    buses in the root port:

    pci 0000:07:00.0: [8086:1578] type 01 class 0x060400
    pci 0000:07:00.0: scanning [bus 00-00] behind bridge, pass 0
    pci 0000:07:00.0: bridge configuration invalid ([bus 00-00]), reconfiguring
    pci 0000:07:00.0: scanning [bus 00-00] behind bridge, pass 1
    pci_bus 0000:08: busn_res: can not insert [bus 08-ff] under [bus 07-3f] (conflicts with (null) [bus 07-3f])
    pci_bus 0000:08: scanning bus
    ...
    pci_bus 0000:0a: bus scan returning with max=40
    pci_bus 0000:0a: busn_res: [bus 0a-ff] end is updated to 40
    pci_bus 0000:0a: [bus 0a-40] partially hidden behind bridge 0000:07 [bus 07-3f]
    pci_bus 0000:08: bus scan returning with max=40
    pci_bus 0000:08: busn_res: [bus 08-ff] end is updated to 40

    Instead of allowing this, limit the subordinate number to be less than or
    equal the maximum subordinate number allocated for the parent bus (if it
    has any).

    Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
    [bhelgaas: remove irrelevant dmesg messages]
    Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

    Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
    ---
    drivers/pci/probe.c | 7 ++++++-
    1 file changed, 6 insertions(+), 1 deletion(-)

    diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
    index 60bada90cd75..a98be6db7e93 100644
    --- a/drivers/pci/probe.c
    +++ b/drivers/pci/probe.c
    @@ -932,7 +932,8 @@ int pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max, int pass)
    child = pci_add_new_bus(bus, dev, max+1);
    if (!child)
    goto out;
    - pci_bus_insert_busn_res(child, max+1, 0xff);
    + pci_bus_insert_busn_res(child, max+1,
    + bus->busn_res.end);
    }
    max++;
    buses = (buses & 0xff000000)
    @@ -2136,6 +2137,10 @@ unsigned int pci_scan_child_bus(struct pci_bus *bus)
    if (bus->self && bus->self->is_hotplug_bridge && pci_hotplug_bus_size) {
    if (max - bus->busn_res.start < pci_hotplug_bus_size - 1)
    max = bus->busn_res.start + pci_hotplug_bus_size - 1;
    +
    + /* Do not allocate more buses than we have room left */
    + if (max > bus->busn_res.end)
    + max = bus->busn_res.end;
    }

    /*
    --
    2.11.0
    \
     
     \ /
      Last update: 2017-12-07 18:13    [W:4.386 / U:0.328 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site