Patchwork PCI: move down pci_fixup_final for hotplug path

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Submitter Bjorn Helgaas
Date May 7, 2013, 9:32 p.m.
Message ID <20130507213250.GA22773@google.com>
Download mbox | patch
Permalink /patch/242467/
State Accepted
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Comments

Bjorn Helgaas - May 7, 2013, 9:32 p.m.
On Thu, Apr 25, 2013 at 06:47:07PM -0700, Yinghai Lu wrote:
> David found some resource conflict issue after
> | PCI: Put pci_dev in device tree as early as possible
> | commit 4f535093cf8f6da8cfda7c36c2c1ecd2e9586ee4
> 
> and
> | USB: Fix handoff when BIOS disables host PCI device
> | commit: cab928ee1f221c9cc48d6615070fefe2e444384a
> 
> for usb qirks for hotplug path.
> 
> After checking pci_fixup_device() with pci_fixup_final,
> now we have different path for boot path and hotadd path.
> 
> Boot path: because pci_apply_fix_final_quirks is not set yet,
> 	so pci_fixup_device(pci_fixup_final) will be skipped
> 	from pci_device_add().
>         And later pci_apply_final_quirks will be called for all
> 	pci devices via fs_initcall.
> 	That is after pci_assign_unassign resource.
> 	In that case quirk could use bars with problem.
> 
> Hotadd path: pci_fixup_device(pci_fixup_final) will be executed
> 	via pci_device_add(), and that is too early for hotplug
> 	path, as pci bar for hot add devices is not assigned yet
> 	after commit 4f535093.
> 
> So we need to move down that for hotplug path, call that in
> pci_bus_add_devices instead, as at that time just before
> drivers get attached. 
> And that is simliar calling place for pci_device_add before
> commit 4f535093 is applied.
> 
> We should apply this fix for v3.9, but is too late now.
> so get it into v3.10 and could get into v3.9 stable instead.
> 
> Reported-by: David Bulkow <David.Bulkow@stratus.com>
> Tested-by: David Bulkow <David.Bulkow@stratus.com>
> Signed-off-by: Yinghai Lu <yinghai@kernel.org>

I applied the following slightly tweaked patch to for-linus and will
ask Linus to pull it for v3.10.  Let me know if it looks OK.

Bjorn

commit a939563f3fd9cd6226c7fb7135d0b93507c53888
Author: Bjorn Helgaas <bhelgaas@google.com>
Date:   Tue May 7 14:35:44 2013 -0600

    PCI: Delay final fixups until resources are assigned
    
    Commit 4f535093cf "PCI: Put pci_dev in device tree as early as possible"
    moved final fixups from pci_bus_add_device() to pci_device_add().  But
    pci_device_add() happens before resource assignment, so BARs may not be
    valid yet.
    
    Typical flow for hot-add:
    
        pciehp_configure_device
          pci_scan_slot
            pci_scan_single_device
              pci_device_add
                pci_fixup_device(pci_fixup_final, dev)  # previous location
          # resource assignment happens here
          pci_bus_add_devices
            pci_bus_add_device
              pci_fixup_device(pci_fixup_final, dev)    # new location
    
    [bhelgaas: changelog, move fixups to pci_bus_add_device()]
    Reference: https://lkml.kernel.org/r/20130415182614.GB9224@xanatos
    Reported-by: David Bulkow <David.Bulkow@stratus.com>
    Tested-by: David Bulkow <David.Bulkow@stratus.com>
    Signed-off-by: Yinghai Lu <yinghai@kernel.org>
    Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
    CC: stable@vger.kernel.org	# v3.9+

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Bjorn Helgaas - May 7, 2013, 9:38 p.m.
On Tue, May 7, 2013 at 2:32 PM, Bjorn Helgaas <bhelgaas@google.com> wrote:
> On Thu, Apr 25, 2013 at 06:47:07PM -0700, Yinghai Lu wrote:
>> David found some resource conflict issue after
>> | PCI: Put pci_dev in device tree as early as possible
>> | commit 4f535093cf8f6da8cfda7c36c2c1ecd2e9586ee4
>>
>> and
>> | USB: Fix handoff when BIOS disables host PCI device
>> | commit: cab928ee1f221c9cc48d6615070fefe2e444384a
>>
>> for usb qirks for hotplug path.
>>
>> After checking pci_fixup_device() with pci_fixup_final,
>> now we have different path for boot path and hotadd path.
>>
>> Boot path: because pci_apply_fix_final_quirks is not set yet,
>>       so pci_fixup_device(pci_fixup_final) will be skipped
>>       from pci_device_add().
>>         And later pci_apply_final_quirks will be called for all
>>       pci devices via fs_initcall.
>>       That is after pci_assign_unassign resource.
>>       In that case quirk could use bars with problem.
>>
>> Hotadd path: pci_fixup_device(pci_fixup_final) will be executed
>>       via pci_device_add(), and that is too early for hotplug
>>       path, as pci bar for hot add devices is not assigned yet
>>       after commit 4f535093.
>>
>> So we need to move down that for hotplug path, call that in
>> pci_bus_add_devices instead, as at that time just before
>> drivers get attached.
>> And that is simliar calling place for pci_device_add before
>> commit 4f535093 is applied.
>>
>> We should apply this fix for v3.9, but is too late now.
>> so get it into v3.10 and could get into v3.9 stable instead.
>>
>> Reported-by: David Bulkow <David.Bulkow@stratus.com>
>> Tested-by: David Bulkow <David.Bulkow@stratus.com>
>> Signed-off-by: Yinghai Lu <yinghai@kernel.org>
>
> I applied the following slightly tweaked patch to for-linus and will
> ask Linus to pull it for v3.10.  Let me know if it looks OK.
>
> Bjorn
>
> commit a939563f3fd9cd6226c7fb7135d0b93507c53888
> Author: Bjorn Helgaas <bhelgaas@google.com>

(I did already fix the Author: to be Yinghai, sorry about that)

> Date:   Tue May 7 14:35:44 2013 -0600
>
>     PCI: Delay final fixups until resources are assigned
>
>     Commit 4f535093cf "PCI: Put pci_dev in device tree as early as possible"
>     moved final fixups from pci_bus_add_device() to pci_device_add().  But
>     pci_device_add() happens before resource assignment, so BARs may not be
>     valid yet.
>
>     Typical flow for hot-add:
>
>         pciehp_configure_device
>           pci_scan_slot
>             pci_scan_single_device
>               pci_device_add
>                 pci_fixup_device(pci_fixup_final, dev)  # previous location
>           # resource assignment happens here
>           pci_bus_add_devices
>             pci_bus_add_device
>               pci_fixup_device(pci_fixup_final, dev)    # new location
>
>     [bhelgaas: changelog, move fixups to pci_bus_add_device()]
>     Reference: https://lkml.kernel.org/r/20130415182614.GB9224@xanatos
>     Reported-by: David Bulkow <David.Bulkow@stratus.com>
>     Tested-by: David Bulkow <David.Bulkow@stratus.com>
>     Signed-off-by: Yinghai Lu <yinghai@kernel.org>
>     Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
>     CC: stable@vger.kernel.org  # v3.9+
>
> diff --git a/drivers/pci/bus.c b/drivers/pci/bus.c
> index 748f8f3..32e66a6 100644
> --- a/drivers/pci/bus.c
> +++ b/drivers/pci/bus.c
> @@ -174,6 +174,7 @@ int pci_bus_add_device(struct pci_dev *dev)
>          * Can not put in pci_device_add yet because resources
>          * are not assigned yet for some devices.
>          */
> +       pci_fixup_device(pci_fixup_final, dev);
>         pci_create_sysfs_dev_files(dev);
>
>         dev->match_driver = true;
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index 43ece5d..67cd045 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -1341,7 +1341,6 @@ void pci_device_add(struct pci_dev *dev, struct pci_bus *bus)
>         list_add_tail(&dev->bus_list, &bus->devices);
>         up_write(&pci_bus_sem);
>
> -       pci_fixup_device(pci_fixup_final, dev);
>         ret = pcibios_add_device(dev);
>         WARN_ON(ret < 0);
>
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Yinghai Lu - May 7, 2013, 10:36 p.m.
On Tue, May 7, 2013 at 2:38 PM, Bjorn Helgaas <bhelgaas@google.com> wrote:
> On Tue, May 7, 2013 at 2:32 PM, Bjorn Helgaas <bhelgaas@google.com> wrote:
>>
>>     PCI: Delay final fixups until resources are assigned
>>
>>     Commit 4f535093cf "PCI: Put pci_dev in device tree as early as possible"
>>     moved final fixups from pci_bus_add_device() to pci_device_add().  But
>>     pci_device_add() happens before resource assignment, so BARs may not be
>>     valid yet.
>>
>>     Typical flow for hot-add:
>>
>>         pciehp_configure_device
>>           pci_scan_slot
>>             pci_scan_single_device
>>               pci_device_add
>>                 pci_fixup_device(pci_fixup_final, dev)  # previous location
>>           # resource assignment happens here
>>           pci_bus_add_devices
>>             pci_bus_add_device
>>               pci_fixup_device(pci_fixup_final, dev)    # new location
>>
>>     [bhelgaas: changelog, move fixups to pci_bus_add_device()]

Yes, that is right fix.

Thanks

Yinghai
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Patch

diff --git a/drivers/pci/bus.c b/drivers/pci/bus.c
index 748f8f3..32e66a6 100644
--- a/drivers/pci/bus.c
+++ b/drivers/pci/bus.c
@@ -174,6 +174,7 @@  int pci_bus_add_device(struct pci_dev *dev)
 	 * Can not put in pci_device_add yet because resources
 	 * are not assigned yet for some devices.
 	 */
+	pci_fixup_device(pci_fixup_final, dev);
 	pci_create_sysfs_dev_files(dev);
 
 	dev->match_driver = true;
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 43ece5d..67cd045 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -1341,7 +1341,6 @@  void pci_device_add(struct pci_dev *dev, struct pci_bus *bus)
 	list_add_tail(&dev->bus_list, &bus->devices);
 	up_write(&pci_bus_sem);
 
-	pci_fixup_device(pci_fixup_final, dev);
 	ret = pcibios_add_device(dev);
 	WARN_ON(ret < 0);