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 grabing 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>
Reviewed-by: Michael Kelley <mikelley@xxxxxxxxxxxxx>
Reviewed-by: Long Li <longli@xxxxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
---
v2:
No change to the patch body.
Improved the commit message [Michael Kelley]
Added Cc:stable
v3:
Added Michael's and Long Li's Reviewed-by.
Fixed a typo in the commit message: grubing -> grabing [Thanks, Michael!]
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
