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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 Sat, Sep 8, 2012 at 6:42 AM, Fengguang Wu <fengguang.wu@intel.com> wrote:
> On Fri, Sep 07, 2012 at 06:32:48PM -0700, Yinghai Lu wrote:
>
>> > 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.
>
> This makes lspci work again on my side. The caveat is, kzalloc() will
> zero out all data while the new local variable leaves some data
> uninitialized.
>
> diff --git a/drivers/pci/search.c b/drivers/pci/search.c
> index 78a08b1..9148b6e 100644
> --- a/drivers/pci/search.c
> +++ b/drivers/pci/search.c
> @@ -245,7 +245,12 @@ 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_device_id id;
> + struct pci_device_id id = {
> + .vendor = vendor,
> + .device = device,
> + .subvendor = ss_vendor,
> + .subdevice = ss_device,
> + };
>
> /*
> * pci_find_subsys() can be called on the ide_setup() path,
> @@ -256,11 +261,6 @@ struct pci_dev *pci_get_subsys(unsigned int vendor, unsigned int device,
> if (unlikely(no_pci_devices()))
> return NULL;
>
> - id.vendor = vendor;
> - id.device = device;
> - id.subvendor = ss_vendor;
> - id.subdevice = ss_device;
> -

yes, here forget to clear .class and .class_mask

> return pci_get_dev_by_id(&id, from);
> }
>
> @@ -300,11 +300,14 @@ 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_device_id id;
> -
> - id.vendor = id.device = id.subvendor = id.subdevice = PCI_ANY_ID;
> - id.class_mask = PCI_ANY_ID;
> - id.class = class;
> + struct pci_device_id id = {
> + .vendor = PCI_ANY_ID,
> + .device = PCI_ANY_ID,
> + .subvendor = PCI_ANY_ID,
> + .subdevice = PCI_ANY_ID,
> + .class_mask = PCI_ANY_ID,
> + .class = class,
> + };
>
> return pci_get_dev_by_id(&id, from);
> }


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