[Please ignore this is a test] pci-hyperv: properly handle pci bus remove

[Please ignore this is a test] pci-hyperv: properly handle pci bus remove

[Long Li]

From: Long Li <longli@microsoft.com>

hv_pci_devices_present is called in hv_pci_remove when we remove a PCI 
device from host (e.g. by disabling SRIOV 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 status hv_pcibus_removed, we can avoid this situation.

Signed-off-by: Long Li <longli@microsoft.com>
---
 drivers/pci/host/pci-hyperv.c | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/drivers/pci/host/pci-hyperv.c b/drivers/pci/host/pci-hyperv.c
index ada9856..8a92244 100644
--- a/drivers/pci/host/pci-hyperv.c
+++ b/drivers/pci/host/pci-hyperv.c
@@ -350,6 +350,7 @@ enum hv_pcibus_state {
 	hv_pcibus_init = 0,
 	hv_pcibus_probed,
 	hv_pcibus_installed,
+	hv_pcibus_removed,
 	hv_pcibus_maximum
 };
 
@@ -1504,12 +1505,19 @@ 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);
 	}
 
@@ -2185,6 +2193,7 @@ 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
@@ -2348,6 +2357,7 @@ 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;
 	}
 
 	hv_pci_bus_exit(hdev);
-- 
2.7.4

Re: [Please ignore this is a test] pci-hyperv: properly handle pci bus remove

[kbuild test robot]

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Hi Long,

[auto build test WARNING on pci/next]
[also build test WARNING on v4.11-rc3 next-20170324]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Long-Li/pci-hyperv-properly-handle-pci-bus-remove/20170326-180444
base:   https://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci.git next
config: x86_64-randconfig-x016-201713 (attached as .config)
compiler: gcc-6 (Debian 6.2.0-3) 6.2.0 20160901
reproduce:
        # save the attached .config to linux build tree
        make ARCH=x86_64 

All warnings (new ones prefixed by >>):

   drivers/pci/host/pci-hyperv.c: In function 'pci_devices_present_work':
>> drivers/pci/host/pci-hyperv.c:1508:2: warning: enumeration value 'hv_pcibus_removed' not handled in switch [-Wswitch]
     switch(hbus->state) {
     ^~~~~~
>> drivers/pci/host/pci-hyperv.c:1508:2: warning: enumeration value 'hv_pcibus_maximum' not handled in switch [-Wswitch]

vim +/hv_pcibus_removed +1508 drivers/pci/host/pci-hyperv.c

  1492					put_pcichild(hpdev, hv_pcidev_ref_childlist);
  1493					list_move_tail(&hpdev->list_entry, &removed);
  1494					break;
  1495				}
  1496			}
  1497		} while (found);
  1498		spin_unlock_irqrestore(&hbus->device_list_lock, flags);
  1499	
  1500		/* Delete everything that should no longer exist. */
  1501		while (!list_empty(&removed)) {
  1502			hpdev = list_first_entry(&removed, struct hv_pci_dev,
  1503						 list_entry);
  1504			list_del(&hpdev->list_entry);
  1505			put_pcichild(hpdev, hv_pcidev_ref_initial);
  1506		}
  1507	
> 1508		switch(hbus->state) {
  1509		case hv_pcibus_installed:
  1510			/*
  1511			* Tell the core to rescan bus
  1512			* because there may have been changes.
  1513			*/
  1514			pci_lock_rescan_remove();
  1515			pci_scan_child_bus(hbus->pci_bus);
  1516			pci_unlock_rescan_remove();

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

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