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    SubjectRe: [PATCH 1/2] PCI: Use local parameter pci_device_id for pci_get_subsys/class()
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    On Thu, Aug 23, 2012 at 12:45 AM, Feng Tang <feng.tang@intel.com> wrote:
    > From 57a28ee5e7662ca28ba4c793aa037d64bd082dee Mon Sep 17 00:00:00 2001
    > From: Feng Tang <feng.tang@intel.com>
    > Date: Wed, 22 Aug 2012 15:41:51 +0800
    > Subject: [PATCH 1/2] PCI: Use local parameter pci_device_id for pci_get_subsys/class()
    >
    > This fixes a kernel warning https://lkml.org/lkml/2012/7/31/682
    >
    > pci_get_subsys() may get called in late system reboot stage, using
    > a sleepable kmalloc() sounds fragile and will casue a kernel warning
    > with my recent commmit 55c844a "x86/reboot: Fix a warning message
    > triggered by stop_other_cpus()" which disable local interrupt in
    > late system shutdown/reboot phase. Using a local parameter instead
    > will fix it and make it eligible for calling forom atomic context.
    >
    > Do the same change for the pci_get_class() as suggeted by Bjorn Helgaas
    >
    > Bisected-by: Fengguang Wu <fengguang.wu@intel.com>
    > Signed-off-by: Feng Tang <feng.tang@intel.com>
    > Reviewed-by: Fengguang Wu <fengguang.wu@intel.com>
    > ---
    > drivers/pci/search.c | 35 +++++++++++------------------------
    > 1 files changed, 11 insertions(+), 24 deletions(-)
    >
    > diff --git a/drivers/pci/search.c b/drivers/pci/search.c
    > index 993d4a0..78a08b1 100644
    > --- a/drivers/pci/search.c
    > +++ b/drivers/pci/search.c
    > @@ -245,8 +245,7 @@ struct pci_dev *pci_get_subsys(unsigned int vendor, unsigned int device,
    > unsigned int ss_vendor, unsigned int ss_device,
    > struct pci_dev *from)
    > {
    > - struct pci_dev *pdev;
    > - struct pci_device_id *id;
    > + struct pci_device_id id;
    >
    > /*
    > * pci_find_subsys() can be called on the ide_setup() path,
    > @@ -257,18 +256,12 @@ struct pci_dev *pci_get_subsys(unsigned int vendor, unsigned int device,
    > if (unlikely(no_pci_devices()))
    > return NULL;
    >
    > - id = kzalloc(sizeof(*id), GFP_KERNEL);
    > - if (!id)
    > - return NULL;
    > - id->vendor = vendor;
    > - id->device = device;
    > - id->subvendor = ss_vendor;
    > - id->subdevice = ss_device;
    > -
    > - pdev = pci_get_dev_by_id(id, from);
    > - kfree(id);
    > + id.vendor = vendor;
    > + id.device = device;
    > + id.subvendor = ss_vendor;
    > + id.subdevice = ss_device;
    >
    > - return pdev;
    > + return pci_get_dev_by_id(&id, from);
    > }
    >
    > /**
    > @@ -307,19 +300,13 @@ pci_get_device(unsigned int vendor, unsigned int device, struct pci_dev *from)
    > */
    > struct pci_dev *pci_get_class(unsigned int class, struct pci_dev *from)
    > {
    > - struct pci_dev *dev;
    > - struct pci_device_id *id;
    > + struct pci_device_id id;
    >
    > - id = kzalloc(sizeof(*id), GFP_KERNEL);
    > - if (!id)
    > - return NULL;
    > - id->vendor = id->device = id->subvendor = id->subdevice = PCI_ANY_ID;
    > - id->class_mask = PCI_ANY_ID;
    > - id->class = class;
    > + id.vendor = id.device = id.subvendor = id.subdevice = PCI_ANY_ID;
    > + id.class_mask = PCI_ANY_ID;
    > + id.class = class;
    >
    > - dev = pci_get_dev_by_id(id, from);
    > - kfree(id);
    > - return dev;
    > + return pci_get_dev_by_id(&id, from);
    > }
    >
    > /**

    with this one in pci/next pci config in /sys are not created.

    10:~ # lspci -tv
    pcilib: Cannot open /sys/bus/pci/devices/0000:00:03.0/config
    lspci: Unable to read the standard configuration space header of
    device 0000:00:03.0
    pcilib: Cannot open /sys/bus/pci/devices/0000:00:02.0/config
    lspci: Unable to read the standard configuration space header of
    device 0000:00:02.0
    pcilib: Cannot open /sys/bus/pci/devices/0000:00:01.3/config
    lspci: Unable to read the standard configuration space header of
    device 0000:00:01.3
    pcilib: Cannot open /sys/bus/pci/devices/0000:00:01.1/config
    lspci: Unable to read the standard configuration space header of
    device 0000:00:01.1
    pcilib: Cannot open /sys/bus/pci/devices/0000:00:01.0/config
    lspci: Unable to read the standard configuration space header of
    device 0000:00:01.0
    pcilib: Cannot open /sys/bus/pci/devices/0000:00:00.0/config
    lspci: Unable to read the standard configuration space header of
    device 0000:00:00.0
    -[0000:00]-

    bisected to this commit

    ccee7d23102f5e5765ec24779c5b77472af8f79e is the first bad commit
    commit ccee7d23102f5e5765ec24779c5b77472af8f79e
    Author: Feng Tang <feng.tang@intel.com>
    Date: Thu Aug 23 15:45:03 2012 +0800

    PCI: Use pci_device_id on stack for pci_get_subsys/class() to avoid kmalloc

    This fixes a kernel warning https://lkml.org/lkml/2012/7/31/682

    pci_get_subsys() may get called in late system reboot stage, using
    a sleepable kmalloc() sounds fragile and will cause a kernel warning
    with my recent commmit 55c844a "x86/reboot: Fix a warning message
    triggered by stop_other_cpus()" which disable local interrupt in
    late system shutdown/reboot phase. Using a local parameter instead
    will fix it and make it eligible for calling forom atomic context.

    Do the same change for the pci_get_class() as suggested by Bjorn Helgaas

    [bhelgaas: changelog]
    Bisected-by: Fengguang Wu <fengguang.wu@intel.com>
    Signed-off-by: Feng Tang <feng.tang@intel.com>
    Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
    Reviewed-by: Fengguang Wu <fengguang.wu@intel.com>

    :040000 040000 dee62a035816b73abc68e40de8f21c7349efc4cb
    70b2a6258bffa1ab963bd650d8f5d02da774fbce M drivers

    so the stack get overrun ?

    Bjorn, I think it is this one that cause lspci broken that I mentioned
    during meeting at San Diego.

    Thanks

    Yinghai


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