[PATCH AUTOSEL for 4.9 062/219] PCI: hv: Properly handle PCI bus remove

Sasha Levin
2018-03-03T22:32:55Z

From: Long Li <longli@microsoft.com>

[ Upstream commit d3a78d8bf759d8848339dcc367c4c1678b57a08b ]

hv_pci_devices_present() is called in hv_pci_remove() when we remove a PCI
device from the host, e.g., by disabling SR-IOV on a device. In
hv_pci_remove(), the bus is already removed before the call, so we don't
need to rescan the bus in the workqueue scheduled from
hv_pci_devices_present().

By introducing bus state hv_pcibus_removed, we can avoid this situation.

Reported-by: Xiaofeng Wang <xiaofwan@redhat.com>
Signed-off-by: Long Li <longli@microsoft.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
---
drivers/pci/host/pci-hyperv.c | 20 +++++++++++++++++---
1 file changed, 17 insertions(+), 3 deletions(-)

diff --git a/drivers/pci/host/pci-hyperv.c b/drivers/pci/host/pci-hyperv.c
index dafb4cdb2b7f..43aa630f419a 100644
--- a/drivers/pci/host/pci-hyperv.c
+++ b/drivers/pci/host/pci-hyperv.c
@@ -351,6 +351,7 @@ enum hv_pcibus_state {
hv_pcibus_init = 0,
hv_pcibus_probed,
hv_pcibus_installed,
+ hv_pcibus_removed,
hv_pcibus_maximum
};

@@ -1489,13 +1490,24 @@ static void pci_devices_present_work(struct work_struct *work)
put_pcichild(hpdev, hv_pcidev_ref_initial);
}

- /* Tell the core to rescan bus because there may have been changes. */
- if (hbus->state == hv_pcibus_installed) {
+ switch(hbus->state) {
+ case hv_pcibus_installed:
+ /*
+ * Tell the core to rescan bus
+ * because there may have been changes.
+ */
pci_lock_rescan_remove();
pci_scan_child_bus(hbus->pci_bus);
pci_unlock_rescan_remove();
- } else {
+ break;
+
+ case hv_pcibus_init:
+ case hv_pcibus_probed:
survey_child_resources(hbus);
+ break;
+
+ default:
+ break;
}

up(&hbus->enum_sem);
@@ -2170,6 +2182,7 @@ static int hv_pci_probe(struct hv_device *hdev,
hbus = kzalloc(sizeof(*hbus), GFP_KERNEL);
if (!hbus)
return -ENOMEM;
+ hbus->state = hv_pcibus_init;

/*
* The PCI bus "domain" is what is called "segment" in ACPI and
@@ -2312,6 +2325,7 @@ static int hv_pci_remove(struct hv_device *hdev)
pci_stop_root_bus(hbus->pci_bus);
pci_remove_root_bus(hbus->pci_bus);
pci_unlock_rescan_remove();
+ hbus->state = hv_pcibus_removed;
}

ret = hv_send_resources_released(hdev);
--
2.14.1