On Tuesday, February 12, 2013 05:54:08 PM Yinghai Lu wrote: > On Tue, Feb 12, 2013 at 4:16 PM, Rafael J. Wysocki <rjw@xxxxxxx> wrote: > > From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> > > > > After commit 1aeae82 (ACPI / PCI: avoid building pci_slot as module) > > the pci_slot driver's .add() callback routine, acpi_pci_slot_add(), > > is executed from within acpi_pci_root_add() before the PCI devices on > > the bus are enumerated and that triggers the WARN_ON() in > > kobject_get(): > > > > WARNING: at /scratch/rafael/work/test/include/linux/kref.h:42 kobject_get+0x33/0x40() > > Hardware name: PORTEGE R500 > > Modules linked in: > > Pid: 1, comm: swapper/0 Not tainted 3.8.0-rc7+ #160 > > Call Trace: > > [<ffffffff8103d38a>] warn_slowpath_common+0x7a/0xb0 > > [<ffffffff8103d3d5>] warn_slowpath_null+0x15/0x20 > > [<ffffffff812f99b3>] kobject_get+0x33/0x40 > > [<ffffffff81452b82>] get_device+0x12/0x30 > > [<ffffffff8138df7b>] register_slot+0x243/0x295 > > [<ffffffff810a7b6d>] ? trace_hardirqs_on+0xd/0x10 > > [<ffffffff8137b7b9>] acpi_ns_walk_namespace+0x10f/0x24a > > [<ffffffff8138dd38>] ? walk_p2p_bridge+0x13b/0x13b > > [<ffffffff8138dd38>] ? walk_p2p_bridge+0x13b/0x13b > > [<ffffffff8137bdc3>] acpi_walk_namespace+0xe9/0x132 > > [<ffffffff8138dd38>] ? walk_p2p_bridge+0x13b/0x13b > > [<ffffffff8138dcf5>] walk_p2p_bridge+0xf8/0x13b > > [<ffffffff8134d606>] ? acpi_os_signal_semaphore+0x76/0x87 > > [<ffffffff8138dd38>] ? walk_p2p_bridge+0x13b/0x13b > > [<ffffffff8137b7b9>] acpi_ns_walk_namespace+0x10f/0x24a > > [<ffffffff8138dbfd>] ? do_sta_before_sun+0x2b/0x2b > > [<ffffffff8138dbfd>] ? do_sta_before_sun+0x2b/0x2b > > [<ffffffff8137bdc3>] acpi_walk_namespace+0xe9/0x132 > > [<ffffffff81356071>] ? acpi_pci_root_add+0x3e7/0x49a > > [<ffffffff8138e07f>] acpi_pci_slot_add+0xb2/0x103 > > [<ffffffff8138dd38>] ? walk_p2p_bridge+0x13b/0x13b > > [<ffffffff81356089>] acpi_pci_root_add+0x3ff/0x49a > > > > which means that pci_bus->dev used in register_slot() has not been > > registered yet at that point. > > > > To fix this use the observation that before commit 1aeae82 > > acpi_pci_slot_add() was always run after pci_bus_add_devices() > > and that happened to the acpiphp's .add() callback routine too. > > Thus it is safe to reorder acpi_pci_root_add() to make the PCI root > > drivers' .add() callbacks be run after pci_bus_add_devices(), so do > > that. > > > > This approach was previously proposed by Myron Stowe. > > > > References: https://patchwork.kernel.org/patch/1848781/ > > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> > > --- > > > > The commit mentioned in the changelog above is in linux-pm.git/linux-next. > > > > Thanks, > > Rafael > > > > --- > > drivers/acpi/pci_root.c | 13 ++++++++----- > > 1 file changed, 8 insertions(+), 5 deletions(-) > > > > Index: test/drivers/acpi/pci_root.c > > =================================================================== > > --- test.orig/drivers/acpi/pci_root.c > > +++ test/drivers/acpi/pci_root.c > > @@ -600,17 +600,20 @@ static int acpi_pci_root_add(struct acpi > > if (system_state != SYSTEM_BOOTING) > > pci_assign_unassigned_bus_resources(root->bus); > > > > + /* need to after hot-added ioapic is registered */ > > + if (system_state != SYSTEM_BOOTING) > > + pci_enable_bridges(root->bus); > > + > > + pci_bus_add_devices(root->bus); > > + > > mutex_lock(&acpi_pci_root_lock); > > + > > list_for_each_entry(driver, &acpi_pci_drivers, node) > > if (driver->add) > > driver->add(root); > > - mutex_unlock(&acpi_pci_root_lock); > > > > - /* need to after hot-added ioapic is registered */ > > - if (system_state != SYSTEM_BOOTING) > > - pci_enable_bridges(root->bus); > > + mutex_unlock(&acpi_pci_root_lock); > > > > - pci_bus_add_devices(root->bus); > > return 1; > > > > out_del_root: > > > > No, we don't need this after > > | commit 4f535093cf8f6da8cfda7c36c2c1ecd2e9586ee4 > | PCI: Put pci_dev in device tree as early as possible > > in pci/next. > > So we can move that Jiang's patch from your tree to Bjorn's tree? OK, I'm dropping that patch from my tree, then (hopefully, no one has merged my acpi-cleanup branch yet). Bjorn, could you pick up https://patchwork.kernel.org/patch/2003771/ please? 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
