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    Subject[PATCH 3.8 62/81] i7core_edac: Fix PCI device reference count
    Date
    3.8.13.20 -stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Jean Delvare <jdelvare@suse.de>

    commit c0f5eeed0f4cef4f05b74883a7160e7edde58b6a upstream.

    The reference count changes done by pci_get_device can be a little
    misleading when the usage diverges from the most common scheme. The
    reference count of the device passed as the last parameter is always
    decreased, even if the function returns no new device. So if we are
    going to try alternative device IDs, we must manually increment the
    device reference count before each retry. If we don't, we end up
    decreasing the reference count, and after a few modprobe/rmmod cycles
    the PCI devices will vanish.

    In other words and as Alan put it: without this fix the EDAC code
    corrupts the PCI device list.

    This fixes kernel bug #50491:
    https://bugzilla.kernel.org/show_bug.cgi?id=50491

    Signed-off-by: Jean Delvare <jdelvare@suse.de>
    Link: http://lkml.kernel.org/r/20140224093927.7659dd9d@endymion.delvare
    Reviewed-by: Alan Cox <alan@linux.intel.com>
    Cc: Mauro Carvalho Chehab <m.chehab@samsung.com>
    Cc: Doug Thompson <dougthompson@xmission.com>
    Signed-off-by: Borislav Petkov <bp@suse.de>
    Signed-off-by: Kamal Mostafa <kamal@canonical.com>
    ---
    drivers/edac/i7core_edac.c | 9 +++++++--
    1 file changed, 7 insertions(+), 2 deletions(-)

    diff --git a/drivers/edac/i7core_edac.c b/drivers/edac/i7core_edac.c
    index e213d03..04e7b9b 100644
    --- a/drivers/edac/i7core_edac.c
    +++ b/drivers/edac/i7core_edac.c
    @@ -1334,14 +1334,19 @@ static int i7core_get_onedevice(struct pci_dev **prev,
    * is at addr 8086:2c40, instead of 8086:2c41. So, we need
    * to probe for the alternate address in case of failure
    */
    - if (dev_descr->dev_id == PCI_DEVICE_ID_INTEL_I7_NONCORE && !pdev)
    + if (dev_descr->dev_id == PCI_DEVICE_ID_INTEL_I7_NONCORE && !pdev) {
    + pci_dev_get(*prev); /* pci_get_device will put it */
    pdev = pci_get_device(PCI_VENDOR_ID_INTEL,
    PCI_DEVICE_ID_INTEL_I7_NONCORE_ALT, *prev);
    + }

    - if (dev_descr->dev_id == PCI_DEVICE_ID_INTEL_LYNNFIELD_NONCORE && !pdev)
    + if (dev_descr->dev_id == PCI_DEVICE_ID_INTEL_LYNNFIELD_NONCORE &&
    + !pdev) {
    + pci_dev_get(*prev); /* pci_get_device will put it */
    pdev = pci_get_device(PCI_VENDOR_ID_INTEL,
    PCI_DEVICE_ID_INTEL_LYNNFIELD_NONCORE_ALT,
    *prev);
    + }

    if (!pdev) {
    if (*prev) {
    --
    1.8.3.2


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