On 04/27/2011 08:07 AM, Bjorn Helgaas wrote: > On Wed, Apr 27, 2011 at 1:38 AM, Ram Pai <linuxram@xxxxxxxxxx> wrote: >> On Tue, Apr 26, 2011 at 05:25:00PM -0600, Bjorn Helgaas wrote: >>> I'm uneasy about release_child_resources(). This patch doesn't add >>> it, but it does add another use of it. >>> >>> What makes it safe for us to blindly release child resources? If we >>> start with something like this: >>> >>> f2500000-f25fffff : PCI Bus 0000:0d >>> f2500000-f25000ff : 0000:0d:00.0 >>> f2500000-f25000ff : mmc0 >>> >>> and we call release_child_resources() on the top-level bridge window >>> (f2500000-f25fffff), I think we will also release the 0000:0d:00.0 and >>> mmc resources. This might not be a problem at boot-time, when the >>> driver won't have claimed the device yet, but often we want to shuffle >>> resources to make a hot-plugged device work, and then we do have to >>> worry about other drivers. >>> >>> It seems like we need to check whether a driver is bound to a device, >>> and if so, leave its resources alone. I didn't see anything like >>> that, but maybe I missed it. >> >> But pci_assign_unassigned_resources() is called only during boot-time, >> before any resources are assigned to any drivers. right? > > That's true today, but I expect it will be false soon. The problem of > assigning resources and finding that we need to rearrange things is > really the same, whether it occurs at boot-time or at hot-add time. I > think we ought to use the same strategy either way. > > I think we're building on a faulty foundation, and I'd rather fix it > now before we build more things on top of it. pciehp hotplug path is calling pci_assign_unassigned_bridge_resources() instead. it only update the bridge itself and will not go up. Yinghai -- 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
