>>>> 1. For pci devices, we would release their resources in >>>> pci_destroy_dev() regardless of pci device refcount. >>>> 2. When we try to remove pci root bus, there is no devices >>>> need to use the pci_host_bridge resources again, release >>>> pci_host_bridge resources is safe. >>>> 3. In some cases, users woule make mistake, for example, >>>> user get a pci device(increase refcount), but forget to >>>> put this device, then if we do hotplug pci root bus, >>>> it would make all pci devices cannot work after hot add. >>> >>> Can you explain this a little more? Are you talking about a *driver* >>> that forgets to put the device? >> >> Yes, may some pci drivers make a mistake, the refcount control the device object >> release is fine, but I think move the mem resource release out is better. > > If this is caused by driver bugs, I think we need to fix the driver > bugs. Agree, but it's better if pci root bus hotplug could work well regardless of the drviers' bug. After we stop all pci devices, I think no one could uses the resources again, it's no need to free host bridge resource until its refcount reach 0. But this is just my personal opinion :) > > So far all I see here is "it works when I do this." What we need is > an argument for "it's correct to do this." It's certainly possible > that you're already making that argument and I'm just not > understanding it. > >>>> I found this issue in the following case: >>>> 1. I have a raid pci device in my system; >>>> 2. I mount a disk which connect to this raid. >>>> 3. hot remove the pci root bus. >>>> 4. hot add the pci root bus. >>>> 5. found the resource conflicts for the children pci devices under this root bus. >>>> >>>> pci_root_bus increase a refcount at pci_host_bridge. >>>> pci_root_bus decrease a refcount at pci_host_bridge in >>>> release_pcibus_dev() when pci_root_bus device refcount reach 0. >>>> >>>> pci_dev increase a refcount at pci_bus in pci_alloc_dev(). >>>> pci_dev decrease a refcount at pci_bus in pci_release_dev() >>>> when pci_dev refcount reach 0. >>>> >>>> If any pci device refcount cannot reach 0, then its pci_bus >>>> refcount cannot reach 0 too, the result is pci_host_bridge >>>> refcount cannot reach 0. >>> >>> . >>> >> > > . > -- 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
