Re: [Xen-devel] [PATCH v6 04/30] xen/PCI: Don't use deprecated function pci_scan_bus_parented()

[Yijing Wang <wangyijing@xxxxxxxxxx>]

>>>> +  pci_add_resource(&resources, &ioport_resource);
>>>> +  pci_add_resource(&resources, &iomem_resource);
>>>> +  pci_add_resource(&resources, &busn_resource);
>>>
>>> Since I don't want to export busn_resource, you might have to allocate your
>>> own struct resource for it here.  And, of course, figure out the details of
>>> which PCI domain you're in and whether you need to share one struct
>>> resource across several host bridges in the same domain.
>>
>> Allocate its own resource here is ok for me, as I mentioned in previous 
>> reply,
>> so do we still need to add additional info to figure out which domain own 
>> the bus resource ?
> 
> That's up to the caller.  Only the platform knows which bridges it wants to
> have in the same domain.  In principle, every host bridge could be in its
> own domain, since each bridge is the root of a unique PCI hierarchy.  But
> some platforms have firmware that assumes otherwise.  I have no idea what
> xen assumes.

I'm not xen guy, so I don't know much about it, but because it call 
pci_scan_bus_parented()
before, and in which busn_resource is always shared for different host 
bridges(same domain or not),
I think add a static bus resource(0,255) should be safe, at least, it would not 
introduce new risk.

Something like:

diff --git a/drivers/pci/xen-pcifront.c b/drivers/pci/xen-pcifront.c
index b1ffebe..a69e529 100644
--- a/drivers/pci/xen-pcifront.c
+++ b/drivers/pci/xen-pcifront.c
@@ -446,9 +446,15 @@ static int pcifront_scan_root(struct pcifront_device *pdev,
                                 unsigned int domain, unsigned int bus)
 {
        struct pci_bus *b;
+       LIST_HEAD(resources);
        struct pcifront_sd *sd = NULL;
        struct pci_bus_entry *bus_entry = NULL;
        int err = 0;
+       static struct resource busn_res = {
+               .start = 0,
+               .end = 255,
+               .flags = IORESOURCE_BUS,
+       };

 #ifndef CONFIG_PCI_DOMAINS
        if (domain != 0) {
@@ -470,17 +476,21 @@ static int pcifront_scan_root(struct pcifront_device 
*pdev,
                err = -ENOMEM;
                goto err_out;
        }
+       pci_add_resource(&resources, &ioport_resource);
+       pci_add_resource(&resources, &iomem_resource);
+       pci_add_resource(&resources, &busn_res);
        pcifront_init_sd(sd, domain, bus, pdev);

        pci_lock_rescan_remove();

-       b = pci_scan_bus_parented(&pdev->xdev->dev, bus,
-                                 &pcifront_bus_ops, sd);
+       b = pci_scan_root_bus(&pdev->xdev->dev, bus,
+                                 &pcifront_bus_ops, sd, &resources);
        if (!b) {

Bjorn, what do you think about ?

Thanks!
Yijing.


> 
>>>>    pcifront_init_sd(sd, domain, bus, pdev);
>>>>  
>>>>    pci_lock_rescan_remove();
>>>>  
>>>> -  b = pci_scan_bus_parented(&pdev->xdev->dev, bus,
>>>> -                            &pcifront_bus_ops, sd);
>>>> +  b = pci_scan_root_bus(&pdev->xdev->dev, bus,
>>>> +                            &pcifront_bus_ops, sd, &resources);
>>>>    if (!b) {
>>>>            dev_err(&pdev->xdev->dev,
>>>>                    "Error creating PCI Frontend Bus!\n");
>>>>            err = -ENOMEM;
>>>>            pci_unlock_rescan_remove();
>>>> +          pci_free_resource_list(&resources);
>>>>            goto err_out;
>>>>    }
>>>>  
>>>> @@ -488,7 +494,7 @@ static int pcifront_scan_root(struct pcifront_device 
>>>> *pdev,
>>>>  
>>>>    list_add(&bus_entry->list, &pdev->root_buses);
>>>>  
>>>> -  /* pci_scan_bus_parented skips devices which do not have a have
>>>> +  /* pci_scan_root_bus skips devices which do not have a
>>>>    * devfn==0. The pcifront_scan_bus enumerates all devfn. */
>>>>    err = pcifront_scan_bus(pdev, domain, bus, b);
>>>>  
>>>> -- 
>>>> 1.7.1
>>>>
>>>> --
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>>>> the body of a message to majordomo@xxxxxxxxxxxxxxx
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>>>
>>> .
>>>
>>
>>
>> -- 
>> Thanks!
>> Yijing
>>
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-pci" in
>> the body of a message to majordomo@xxxxxxxxxxxxxxx
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> 
> .
> 


-- 
Thanks!
Yijing


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