From: Dexuan Cui <decui@xxxxxxxxxxxxx> Sent: Monday, April 3, 2023 7:06 PM > > Commit 414428c5da1c ("PCI: hv: Lock PCI bus on device eject") added > pci_lock_rescan_remove() and pci_unlock_rescan_remove() in > create_root_hv_pci_bus() and in hv_eject_device_work() to address the > race between create_root_hv_pci_bus() and hv_eject_device_work(), but it > turns that grubing the pci_rescan_remove_lock mutex is not enough: > refer to the earlier fix "PCI: hv: Add a per-bus mutex state_lock". > > Now with hbus->state_lock and other fixes, the race is resolved, so > remove pci_{lock,unlock}_rescan_remove() in create_root_hv_pci_bus(): > this removes the serialization in hv_pci_probe() and hence allows > async-probing (PROBE_PREFER_ASYNCHRONOUS) to work. > > Add the async-probing flag to hv_pci_drv. > > pci_{lock,unlock}_rescan_remove() in hv_eject_device_work() and in > hv_pci_remove() are still kept: according to the comment before > drivers/pci/probe.c: static DEFINE_MUTEX(pci_rescan_remove_lock), > "PCI device removal routines should always be executed under this mutex". > > Signed-off-by: Dexuan Cui <decui@xxxxxxxxxxxxx> > Cc: stable@xxxxxxxxxxxxxxx > --- > > v2: > No change to the patch body. > Improved the commit message [Michael Kelley] > Added Cc:stable > > drivers/pci/controller/pci-hyperv.c | 11 +++++++++-- > 1 file changed, 9 insertions(+), 2 deletions(-) > > diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c > index 3ae2f99dea8c2..2ea2b1b8a4c9a 100644 > --- a/drivers/pci/controller/pci-hyperv.c > +++ b/drivers/pci/controller/pci-hyperv.c > @@ -2312,12 +2312,16 @@ static int create_root_hv_pci_bus(struct > hv_pcibus_device *hbus) > if (error) > return error; > > - pci_lock_rescan_remove(); > + /* > + * pci_lock_rescan_remove() and pci_unlock_rescan_remove() are > + * unnecessary here, because we hold the hbus->state_lock, meaning > + * hv_eject_device_work() and pci_devices_present_work() can't race > + * with create_root_hv_pci_bus(). > + */ > hv_pci_assign_numa_node(hbus); > pci_bus_assign_resources(bridge->bus); > hv_pci_assign_slots(hbus); > pci_bus_add_devices(bridge->bus); > - pci_unlock_rescan_remove(); > hbus->state = hv_pcibus_installed; > return 0; > } > @@ -4003,6 +4007,9 @@ static struct hv_driver hv_pci_drv = { > .remove = hv_pci_remove, > .suspend = hv_pci_suspend, > .resume = hv_pci_resume, > + .driver = { > + .probe_type = PROBE_PREFER_ASYNCHRONOUS, > + }, > }; > > static void __exit exit_hv_pci_drv(void) > -- > 2.25.1 Reviewed-by: Michael Kelley <mikelley@xxxxxxxxxxxxx>