On Thursday 04 of October 2012 15:46:39 Yinghai Lu wrote: > On Thu, Oct 4, 2012 at 3:36 PM, Rafael J. Wysocki <rjw@xxxxxxx> wrote: > > On Thursday 04 of October 2012 15:01:21 Yinghai Lu wrote: > >> during adding pci root bus hotplug, Bjorn found some unsafe searching > >> that caused by pci_bus_add_devices. > > > > Do you have a link to a description of that problem? > > Maybe bjorn could expand it more. > > > > >> pci devices are created during pci scan root, but until very late > >> acpi_pci_root_start call pci_bus_add_devices. > > > > So you mean that pci_bus_add_devices() is called too late, right? > > yes. > > > > >> To fill the gap, we need to move pci_bus_add_devices to acpi_pci_root_add > >> at first. > >> > >> but after we move that there, pci device will be added to device tree, and it > >> will try to bind with acpi devices that should be under acpi pci root, > >> but are not > >> created yet. because device_add for acpi_device for acpi pci root is done yet. > >> it still calling the .add in the acpi_driver aka acpi_pci_root_add. > > > > Quite obviously, we haven't walked the ACPI namespace below the host bridge > > object yet at that point. > > yes. > > > > >> So I want to hold the driver attach for pci root acpi devices, and > >> later attach it > >> until pci devices created. > >> > >> booting path, all acpi devices get created, and attach driver for them > >> one by one. > > > > I see. > > > > Your patches seem to affect all devices in the ACPI namespace added after > > boot, though, not only host bridges. > > yes, but it still should be safe. I'm not really sure of that (what about undock/dock, for exmaple?) and it's damn ugly. > > And the problem seems to be that the scanning of the ACPI namespace and > > configuring the host bridge are kind of independent operations now. What > > we should do, actually, seems to be something like this: > > > > (1) Configure the host bridge when discovered (i.e. do what the current > > acpi_pci_root_add() does. > > (2) Parse the ACPI namespace under the host bridge (without binding ACPI > > drivers to the struct acpi_device objects created in the process, > > because they are known to correspond to PCI devices). > > (3) Run pci_bus_add_devices() for the bridge. > > > > in one routine. > > problem is still there. if 1 still has acpi_pci_root_add and pci_acpi_scan_root OK, so why don't we do (2) in acpi_pci_root_add(), before pci_acpi_scan_root() is called? > that scan pci devices. what is need is we need to bind 1 and 3 together. I don't understand now. You said previously that we need the ACPI namespace below the bridge to be scanned before (3), so why do you want to do (3) before (2) now? > or we could move pci_scan_root_scan from acpi_pci_root_add to > acpi_pci_root_start? No, I don't think so, because we call acpi_pci_bind_root() after that. Thanks, Rafael -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center. -- 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
